BACKGROUND

Routinely, nephrologists rely on different biochemical markers like intact PTH (iPTH), bone-specific alkaline phosphatase (BALP), plasmatic calcium and phosphate. The aim of the present study was to evaluate different other bone markers like N-terminal propeptide of type 1 procollagen (P1NP), active isoform 5b of the tartrate-resistant acid phosphatase (TRAP 5b) and beta-crossLaps (CTXS) as well as full-length PTH (wPTH), presumed non-(1-84) PTH, and their ratio in the diagnosis of renal osteodystrophy with high and low turnover. We also determined 25 hydroxyvitamin D (25VTD), 1-25 dihydroxyvitamin D and homocystein (HCY).

METHODS

We performed those parameters on 73 patients with end-stage renal disease according to the manufacturers' instructions.

RESULTS

There were very strong correlations between the bone markers concentrations, particularly between BALP and P1NP (r=0.953). We did not observe any correlation between the ratio whole PTH/non-(1-84) PTH and any of the usual bone markers. This ratio was significantly (p<0.05) higher in low and high bone turnover patients than in normal patients according to the K/DOQI. We found a correlation between low levels of 25VTD and high levels of HCY.

CONCLUSIONS

BALP offers the best clinical and analytical profile as the easier marker of choice in hemodialyzed patients for the diagnosis of bone disease.

Residual periodontal ligament (PDL) cells in the damaged tissue are considered a prerequisite for a successful regeneration of the periodontal architecture with all its components, including gingiva, PDL, cementum, and bone. Among other approaches, current concepts in tissue engineering aim at a hormonal support of the regenerative capacity of PDL cells as well as at a supplementation of lost cells for regeneration. Here, we investigated how far an anabolic, intermittent parathyroid hormone (iPTH) administration would enhance the osteoblastic differentiation of PDL cells and the cellular ability to mineralize the extracellular matrix in an in vivo transplantation model. PDL cells were predifferentiated in a standard osteogenic medium for 3 weeks before subcutaneous transplantation into CD-1 nude mice using gelatin sponges as carrier. Daily injections of 40 μg/kg body weight PTH(1-34) or an equivalent dose of vehicle for 4 weeks were followed by explantation of the specimens and an immunohistochemical analysis of the osteoblastic marker proteins alkaline phosphatase (ALP), osteopontin, and osteocalcin. Signs of biomineralization were visualized by means of alizarin red staining. For verification of the systemic effect of iPTH application, blood serum levels of osteocalcin were determined. The osteogenic medium stimulated the expression of ALP and PTH1-receptor mRNA in the cultures. After transplantation, iPTH resulted in an increased cytoplasmic and extracellular immunoreactivity for all markers investigated. In contrast to only sporadic areas of mineralization under control conditions, several foci of mineralization were observed in the iPTH group. Blood serum levels of osteocalcin were elevated significantly with iPTH. These data indicate that the osteoblastic differentiation of human PDL cells and their ability for biomineralization can be positively influenced by iPTH in vivo. These findings hold out a promising prospect for the support of periodontal regeneration.

The remnant kidney rat model has been extensively used for the evaluation of bone changes due to uremia. The present study aimed to assess the effect of the dietary phosphorus availability and of the severity of renal failure on bone histomorphometric changes and various biochemical markers over time in this model. Chronic renal failure (CRF) was induced in male Wistar rats by 5/6th nephrectomy. Half of the number of animals received a standard rat diet (STD) (0.67% P, containing low bioavailable phosphorus of plant origin); the other animals were fed a high phosphorus diet (HPD) (0.93% P, containing inorganic phosphorus with high bioavailability). Every two weeks, blood and urine samples were collected. At sacrifice after 6 or 12 weeks, bone samples were taken for the measurement of histological and histodynamic parameters. Serum creatinine measurements indicated the development of mild to moderate renal failure in both diet groups. Phosphaturia was unexpectedly low in all animals that received the STD, indicating relative phosphorus depletion despite the normal dietary phosphorus content. In the HPD CRF group, a decrease in calcemia and a rise in phosphatemia were seen after 12 weeks of CRF, which were more pronounced in animals with higher serum creatinine. Serum iPTH levels were distinctly increased in CRF rats fed a HPD, especially those with more pronounced renal failure. Serum osteocalcin and to a lesser extend tartrate-resistant acid phosphatase and urinary pyridinoline and deoxypyridinoline crosslinks were higher in the CRF animals compared to the shams, particularly in the animals of the HPD group with more pronounced CRF. In both diet groups, the CRF animals had significantly higher amounts of osteoid compared to shams. Only the animals that received a HPD developed distinct histological signs of secondary hyperparathyroidism (sHPTH), that is, an increased bone formation rate, mineral apposition rate, osteoblast perimeter, and eroded perimeter. Again, this effect was most prominent in rats with more severe CRF. In conclusion, data of the present study indicate that in experimental studies using the remnant kidney rat model, both the dietary phosphorus bioavailability and the degree of renal failure in the development of hyperparathyroidism should be considered.

OBJECTIVE

Hypophosphataemic rickets/osteomalacia (HRO) is an uncommon metabolic bone disorder which affects all ages and either sex. It is characterized by low concentration of serum phosphate levels leading to impairment of mineralization of bone matrix with variable aetiology. We present clinical profile and treatment outcome of 17 patients of HRO.

METHODS

Seventeen consecutive patients (8 were < 18 yr of age, with median age of presentation being 27.5 yr) of HRO who came to the department of Endocrinology in a tertiary care hospital in north India from January 2000 to December 2006 were included in the present study. Their aetiology, clinical features, biochemical parameters, radiographic features, treatment and outcome were analyzed.

RESULTS

HRO was commoner in females (70.5%) with positive family history observed in 6 (35.3%) patients. Common presenting features were short stature (58.8%), backache (58.8%), bony deformities (58.8%), joint pain (52.9%), fractures (29.4%) and dental abnormalities (23.5%). Radiological abnormalities noted were generalized bony deformities (58.8%), fractures (29.4%), and pseudo fractures (17.6%). Mesenchymal tumours were localized in the pelvis in one patient and in the right jaw in another. The patients were treated with calcium (elemental calcium 1 g/d) and oral phosphate supplements (dose 30 - 50mg/kg/day in divided doses) along with active vitamin D supplements (dose 1 - 3 microg/day) and followed up for a mean of 2 yr. Two patients also received growth hormone (GH) therapy in the dose of 2U/day for 6 and 18 months respectively. Symptomatic well being was reported by all the patients and improvement was noted in the levels of phosphate (P<0.005) and alkaline phosphatase (P<0.05) after treatment.

CONCLUSIONS

A diagnosis of HRO should be considered in all patients presenting with short stature, deformities or musculoskeletal pains along with low serum phosphate with normal iPTH and 25--hydroxy vitamin D.

OBJECTIVE

We investigated whether disturbance of calcium and phosphate metabolism is associated with the presence and severity of calcific aortic valve disease (CAVD) in patients with normal or mildly impaired renal function.

METHODS

We measured serum levels of calcium, phosphate, alkaline phosphatase (AKP), intact parathyroid hormone (iPTH), 25-hydroxyvitamin D (25-OHD), and biomarkers of bone turnover in 260 consecutive patients with normal or mildly impaired renal function and aortic valve sclerosis (AVSc) (n=164) or stenosis (AVS) (n=96) and in 164 age- and gender-matched controls. Logistic regression models were used to determine the association of mineral metabolism parameters with the presence and severity of CAVD.

RESULTS

Stepwise increases were observed in serum levels of calcium, phosphate, AKP, and iPTH from the control group to patients with AVS, and with reverse changes for 25-OHD levels (all P<0.001). Similarly, osteocalcin, procollagen I N-terminal peptide, and β-isomerized type I collagen C-telopeptide breakdown products were significantly increased stepwise from the control group to patients with AVS (all P<0.001). In patients with AVS, serum levels of iPTH were positively, in contrast 25-OHD levels were negatively, related to trans-aortic peak flow velocity and mean pressure gradient. After adjusting for relevant confounding variables, increased serum levels of calcium, phosphate, AKP, and iPTH and reduced serum levels of 25-OHD were independently associated with the presence and severity of CAVD.

CONCLUSIONS

This study suggests an association between mineral metabolism disturbance and the presence and severity of CAVD in patients with normal or mildly impaired renal function. Abnormal bone turnover may be a potential mechanism.

Secondary hyperparathyroidism is a common feature of chronic renal failure and vitamin D deficiency plays an important role in the development of this abnormality. Several therapeutical calcitriol schedules have been used in treating uremic hyperparathyroidism but recently oral boluses have been proposed as more effective. In this study we compare the efficacy of three different oral calcitriol regimens in suppressing iPTH secretion in predialytic chronic renal failure. Sixteen (16) patients (mean age 51 +/- 16 years; creatinine clearance 22.9 +/- 9.8 ml; range 8-32 ml/min) were treated in a cross-over randomized design with oral daily calcitriol 0.5 micrograms/die (Treatment A), three oral boluses of 2 micrograms of calcitriol a week (Treatment B) and a single oral bolus of 2 micrograms of calcitriol a week (Treatment C). All treatment periods lasted three months and were followed by a wash-out period of one month. Serum iPTH (Allegro Nichols), 1-25 vitamin D (IRMA-MAB), total and ionized calcium (Nova 8 Pabish), serum phosphate, alkaline phosphatase and creatinine clearance were measured every two weeks. Serum iPTH was also determined in a control group of fifteen (15) patients (mean age 47 +/- 12 years, creatinine clearances of 21 +/-12 ml/min) observed for three months without calcitriol treatment. Daily oral intake of 0.5 micrograms of calcitriol prevents an increase of iPTH without causing hypercalcemia, but only oral boluses (B and C) decreased iPTH: from 270 +/- 169 pg/ml to 135 +/- 76 pg/ml (p < 0.01; B) and to 165 +/- 121 pg/ml (p < 0.05; C). Serum iPTH increased from 293 +/- 121 to 323 +/- 129 pg/ml (p = n.s.). No significant differences in renal function were observed during the different study periods. Our results confirm the good efficacy of multiple calcitriol oral boluses but also suggest for the first time a single weekly bolus as a reliable approach to the treatment of secondary hyperparathyroidism in pre-dialytic renal failure.

Sex steroids are essential for accretion and maintenance of bone mass. Their importance for osteoporotic fractures in men, however, are undefined. We determined circulating levels of testosterone (T), non-SHBG-bound T (bT), free testosterone (FT), oestradiol (E2), intact parathormone (iPTH), 25-OH-vitamin D (25(OH)D), and trabecular bone mineral density at spinal level (tBMD) by single quantitative computed tomography (QCT), respectively, in elderly men 1-3.5 months after minimal traumatic hip fractures (MTHF, age=75+/-10 ys, n=27). A group of patients with non-immobilising stroke (S; age=73+/-8 ys, n=12) served as controls. Men with known secondary osteoporosis were excluded from the study. Furthermore, serum levels of T and E2 were compared to healthy controls aged 20-30 years (n=138) and 60-80 years (n=110). In addition a literature-based analysis of studies on testosterone in men hip fractures were conducted. Mean tBMD of men with MTFH (52.7+/-17.6 mg/cm3, T-score=- 4.5+/-0.6) was significantly lower than in men with S (78+/-16.3 mg/cm3, T-score=- 3.5+/-0.8). Significant differences of the means between both groups were observed for T, bT, and FT but not for E2, 25(OH)D, and iPTH, respectively. About 90 % of men with MTHF had T serum levels 2 SD below the mean of young controls. This proportion reduced to 30 % if compared with serum levels of 60-80-year-old healthy men whereas men after S remained well within the normal range adjusted for age. Mean serum levels of iPTH were within the normal range (1-6.8 pmol/l); 25(OH)D serum levels were at the lower end of the normal control levels (30-190 nmol/l). There was an inverse relationship between iPTH and 25(OH)D (r=- 0,4; p<0,03). In conclusion, low serum T is common in men with MTHF and only partly due to age. It appears to be a primary factor in fragility fractures in men and not simply secondary to morbidity following the fracture. In view of the scarce and inconsistent data published on this issue (1 longitudinal and 6 cross-sectional studies) the present study supports the patho-physiological relevance of low serum testosterone for the occurrence of MTHF in men.

OBJECTIVE

This study aimed to show that during hypokinesia (HK), phosphate (P(i)) imbalance increases more with higher than lower physical activity and that P(i) absorption reduces more with higher than lower P(i) imbalance in subjects with higher than lower muscular activity.

METHODS

Studies were conducted on 30 healthy male subjects during 364 days of HK. They were equally divided in three groups: unrestricted active control subjects (UACS), continuously hypokinetic subjects (CHKS) and periodically hypokinetic subjects (PHKS). CHKS were kept under average walking distances of 0.5+/-0.2 km day(-1) PHKS were kept under average walking distances of 0.5+/-0.1 and running average distances of 8.7+/-1.2 km day(-l) for 5 days and 2 days per week, respectively. UACS were placed under average running distances of 8.7+/-1.2 km day(-l).

RESULTS

P(i) imbalance, serum, urine and fecal P(i) levels, and urine and serum calcium (Ca(2+)) levels increased significantly (p<0.05) and P(i) absorption, and serum intact parathyroid hormone (iPTH) and 1,25-dehydroxyvitamin D (1,25 (OH)(2) D(3)) levels decreased significantly (p<0.05) in CHKS and PHKS compared with their pre-HK values and their respective active control (UACS). However, the P(i) imbalance, serum, urine and fecal P(i) levels, and serum and urine Ca(2+) levels increased more significantly (p<0.05), and P(i) absorption and serum iPTH and 1,25 (OH)(2) D(3) levels decreased more significantly in PHKS than in CHKS.

CONCLUSIONS

Higher P(i) imbalance with higher than lower physical activity shows that the risk of higher P(i) imbalance is inversely related to the intensity of physical activity. Lower P(i) absorption with higher than lower P(i) imbalance shows that the risk of lower P(i) absorption is inversely related to magnitude of P(i) imbalance. In conclusion P(i) imbalance increases more with higher than lower physical activity and that P(i) absorption decreases more with higher than lower P(i) imbalance indicating that during HK the use of P(i) decreases more with higher than lower physical activity.

The aim of this study was to assess the effect of a long-term course of high-dose i.v. pulses of calcitriol (CLT) on hyperparathyroid bone disease (HBD) and functional mass of parathyroid glands of chronically hemodialyzed uremic (CHU) patients. We prospectively studied nine CHU patients treated with CLT, 30 ng/kg/body wt, i.v., thrice weekly over a period of eight months. Plasma concentrations of intact parathyroid hormone (iPTH), bone GLA protein (bGLA) and bone isoenzyme of alkaline phosphatase (biALP) were sampled throughout. Transiliac bone biopsies were made before and after the start of CLT therapy. Double scanning scintigraphy of the neck with 201Tl-99Tc was made before, during and eight months after the start of the treatment. All patients but one, who later responded to higher than planned CLT doses, had significant decreases of plasma iPTH (F = 76; P < 0.0001; ANOVA). The mean pretreatment value of PTH was 966 +/- 160 (mean +/- SE) pg/ml and it had decreased significantly by the first week (T = 2.4, P < 0.04), and had fallen an average of 80% by the 35th week. Ionized plasma calcium concentration was 1.19 +/- .01 mmol/liter which rose significantly (F = 13.5; P < 0.0001) by the 14th week to maximal peak levels, averaging 1.34 +/- .02 mmol/liter. Changes in biALP were parallel to those of iPTH, while bGLA tended to increase immediately after the start of the therapy and to significantly decrease thereafter (T = 3.2; P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

We studied the effects of energy restriction on serum osteocalcin concentration and bone formation rate in rats. The experiment was designed to achieve energy restriction by reducing the carbohydrate intake while providing identical quantities of protein, fat, vitamins and minerals. Energy intakes of three groups of post-weaning male rats were restricted by 20, 40 and 60% for 4 wk. Serum calcium, phosphorus, transthyretin, triiodothyronine (T3), thyroxine (T4), 1,25-dihydroxycholecalciferol, 25-hydroxycholecalciferol and immunoreactive parathyroid hormone (iPTH) concentrations were determined. Energy restriction (20, 40 and 60%) produced a significant and gradual drop of serum osteocalcin concentrations, although the serum concentrations of its key regulators, i.e., 1,25-dihydroxycholecalciferol and iPTH, were not significantly affected. On the contrary, serum concentrations of calcium, phosphorus, transthyretin, T3 and T4 were significantly lower in the energy-restricted groups. However, our results do not support their implication in the regulation of serum osteocalcin synthesis by energy intake. Serum osteocalcin concentration was positively correlated with bone mineral apposition (r = 0.50, P < 0.05) and bone mineralization (r = 0.50, P < 0.05) rates suggesting that its decrease resulted from a reduction of bone formation, and not from abnormal mineralization, because osteoid seam thickness was not modified. Energy intake seems to be an important determinant of serum osteocalcin concentration and bone formation; however, the exact mechanism underlying this regulation remains to be determined.

OBJECTIVE

To evaluate, in premenopausal systemic lupus erythematosus (SLE) patients, the possible protective role of androgens on bone mass.

METHODS

Bone mineral density (BMD) was measured in the lumbar spine and femoral neck in 37 women with SLE (mean age 31.1 years) without disturbances or therapy that could interfere with bone metabolism except glucocorticoid therapy. We measured serum intact parathyroid hormone (iPTH): 2.5 +/- 1.3 pmol/L, serum testosterone: 1.6 +/- 1.1 nmol/L, salivary testosterone: 0.09 +/- 0.1 nmol/L, and serum dehydroepiandrosterone sulphate (DHEAS): 2.2 +/- 2.2 umol/L.

RESULTS

BMD in the spine (L2-L4) was 0.94 +/- 0.1 g/cm2 and in the femoral neck 0.77 +/- 0.1 g/cm2. Four patients (10.8%) had osteoporosis. We found a significant positive relationship between DHEAS and BMD, a negative relationship between DHEAS and the glucocorticoid dose at the time of study, and a negative correlation between iPTH and DHEAS.

CONCLUSIONS

Bone loss in corticosteroid-treated premenopausal patients with SLE may be modulated through down-regulation of the endogenous production of DHEAS.

Direct measurements of parathyroid activity are available in only small numbers of children with vitamin D deficiency rickets (VDR). Therefore serum immunoreactive parathyroid hormone (iPTH) and the urinary cyclic adenosine-3',5'-monophosphate excretion (UcAMP) were measured together with other important indices of calcium metabolism in 24 patients (aged 2-42 months) with VDR before vitamin D treatment. iPTH and UcAMP were significantly elevated in comparison to age-matched controls. In patients there was a highly significant positive correlation between iPTH and UcAMP and a negative relationship between both indices of parathyroid activity to serum phosphate and urine calcium, respectively, indicating that the simple measurement of serum phosphate and/or urine cAMP and Ca provides a reliable tool for the assessment of secondary hyperparathyroidism in VDR. In two patients classified as being in the early stage of VDR the parathyroid activity was not elevated despite hypocalcemia indicating relative hypoparathyroidism. Twelve patients with VDR were followed during vitamin D therapy: Within the first 2 weeks of treatment UcAMP slightly increased and thereafter decreased in most patients, but was still elevated in three patients even after 7 weeks, whereas iPTH became normal within 3 weeks of treatment. This favors the concept that vitamin D deficiency diminishes the activation of renal adenylate cyclase by PTH which is overcome by the highly increased PTH secretion in the advanced stages of rickets. The basal and calcium-stimulated serum calcitonin (CT) levels, determined in some of the patients, were normal, ruling out a significant disturbance of CT secretion in VDR.

The effect of secondary HPT on PMN function, as assessed by CL, was studied in two groups of patients. Group 1 comprised seven patients with no clinical evidence of secondary HPT and mildly elevated levels of serum iPTH (mean 2.7 +/-0.9 microleq/ml), and group 2 had six patients with clinical and radiological evidence of secondary HPT and higher ( p < 0.001) levels of iPTH (mean 26 +/- 7 microleq/ml). PMNs from group 2 patients demonstrated 68% +/- 9 augmented CL in the presence of autologous serum. Cross-incubation studies showed that sera from group 2 patients induced augmented CL in normal PMNs. In contrast, PMNs from group 2 patients showed reduced CL in the presence of normal serum. The augmenting effect of group 2 sera did not correlate with the level of calcium, phosphorus, creatinine, or BUN in serum. After successful subtotal parathyroidectomy, evident by the decrease of serum iPTH levels, both the CL of group 2 PMNs and the ability of group 2 sera to induce augmented CL in normal PMNs decreased (p < 0.025). These results suggest that secondary HPT is directly or indirectly responsible for the altered leukocyte function in some patients with uremia, particularly those with marked elevation of iPTH.

BACKGROUND

The aim of this research was to establish whether there is a link between insulin resistance (IR) and glomerular filtration rate (GFR), and assess whether insulin-resistant subjects experience a more rapid deterioration in GFR.

METHODS

We enrolled 73 non-diabetic chronic kidney disease (CKD) stage 2-4 patients. All blood samples were taken after 10 h of overnight fasting. Fasting blood glucose (FBG), creatinine, uric acid, albumin, cholesterol, triglyceride, insulin, HbA1c, high-sensitivity C-reactive protein (hs-CRP) and intact parathyroid hormone (iPTH) levels as well as proteinuria were analyzed. Patients were followed up for a mean of 30 (24-35) months and renal and metabolic parameters were compared in conjunction with a homeostasis model assessment of IR (HOMA-IR) between the entry and the end of the study period. CKD progression was assessed by recording renal endpoints, which included end-stage renal disease, requiring renal replacement therapy, or overall mortality.

RESULTS

The study patients were divided into group 1 (n = 36), without IR, and group 2 (n = 37), with IR. Group 2 patients had a higher FBG (p = 0.003) and insulin level (p = 0.001) compared to group 1. The baseline and end of study systolic (p = 0.007) and diastolic (p = 0.001) blood pressures were decreased in group 1. In group 2, FBG (p = 0.008), HbA1c (p = 0.009), systolic (p = 0.024) and diastolic (p = 0.001) blood pressures and CRP (p = 0.047) were decreased. In group 2, 8 patients reached renal endpoints while in group 1, 9 patients reached study endpoints. HOMA-IR was not significantly higher among 17 patients who reached the renal endpoint than among the 56 who did not. At baseline, those patients who reached the renal endpoint showed lower GFR (p = 0.001), higher iPTH (p = 0.004) and hs-CRP (p = 0.002) levels.

CONCLUSIONS

There was no significant difference in GFR at the end of the study between patients who had or did not have IR. Furthermore, HOMA-IR was not significantly different in patients with or without renal endpoints.

Rosiglitazone (ROG) has been shown to exert beneficial effects on glycemic control and renal protection. Circulatory fibroblast growth factor‑23 (FGF‑23) is a novel independent risk factor for chronic kidney disease (CKD) progression. The current study focused on how ROG impacts on injury of the kidney, and whether FGF‑23 is involved in the process. A total of 24 male Sprague Dawley rats, weighing 250‑280 g, were divided into four groups (n=6 per group): i) Normal; ii) ROG controls, treated with ROG (10 mg/kg/day); iii) CKD models, treated with adenine (200 mg/kg/day); and iv) ROG treatment, treated with ROG (10 mg/kg/day) and adenine (200 mg/kg/day). The rats were sacrificed after four weeks, and serum, urine and kidney tissues were collected. The data revealed that the serum levels of inorganic phosphate (Pi), intact parathyroid hormone (iPTH) and FGF‑23 were significantly higher in the CKD models compared with those in the normal group (P<0.01), while ROG significantly reduced the serum levels of Pi, iPTH and FGF‑23 (P<0.01). The ratio of protein/creatine (Cr) in the urine and the serum levels of Cr, blood urea nitrogen and uric acid were significantly increased in the CKD models compared with the normal group (P<0.01), however, ROG significantly reduced these parameters (P<0.05). Furthermore, ROG significantly alleviated the tubule interstitial damage index of the CKD models in comparison with that of the controls. These results indicated that ROG mitigates the lesions of chronic kidney disease induced by adenine, and that the system of Pi‑PTH‑FGF‑23 may contribute to this process. The possible mechanisms underlying this process require confirmation in future studies.

Calcium-alpha-ketoglutarate (Ca-ket) is known as a highly effective phosphate (P) binder in hemodialysis (HD) patients. In addition, alpha-ketoglutarate has been shown to improve metabolic alterations. We investigated the effect of long-term P-binding therapy with Ca-ket to determine whether P accumulation is the main reason of secondary hyperparathyroidism (HPT) in HD patients or not. Ca-ket was prescribed to 14 HD patients as a soluble preparation in a mean dosage of 4.5 g/day (0.975 g elemental Ca) for a period of 36 months. Serum P continuously dropped from prestudy 2.6 +/- 0.1 (mean +/- SEM) to 1.9 +/- 0.07 mmol/l (p < 0.001), whereas serum Ca increased from 2.2 +/- 0.1 to 2.47 +/- 0.08 mmol/l (p < 0.05). Thus, Ca/P ratio in serum converted significantly from 0.91 +/- 0.02 (prestudy) to 1.28 +/- 0.01 (p < 0.001). Intact parathyroid hormone (iPTH) continuously normalized in all patients from 29 +/- 5 to 8 +/- 2 pmol/l (p < 0.001). The present data show that long-term treatment with Ca-ket normalizes secondary HPT by simultaneously P binding and correcting Ca/P ratio in serum without vitamin D treatment.

INTRODUCTION Pentraxin3 (PTX3) play an important role in the inflammatory response, taking part in recognizing pathogens and damaged tissues. OBJECTIVES The aim of the study was to assess the relationship between PTX3 levels and all-cause and cardiovascular (CV) mortality in chronic kidney disease (CKD) patients during five-year observation period. PATIENTS AND METHODS The study comprised 78 patients (51 hemodialyzed, 27 predialysis). The examined parameters included PTX3, calcium, phosphate, iPTH, interleukin-6 (IL-6), fibroblast growth factor 23 (FGF-23), osteopontin (OPN), osteoprotegerin (OPG), osteocalcin (OC), osteopontin (OPN), osteoprotegerin (OPG), osteocalcin, tumor necrosis factor receptor II (TNF-R II), transforming growth factor-β (TGF-β), hepatocyte growth factor (HGF), stromal cell-derived factor α (SDF1α), and thrombomodulin (TM). In a subgroup of 45 patients, fragments of radial artery obtained during creation of hemodialysis access were stained for calcifications. In 51 patients, ultrasonography was performed to assess intima-media thickness (CCA-IMT). RESULTS Median serum concentration of PTX3 was 1.43 (0.74-2.50) ng/ml. Higher concentrations of fibrinogen, CRP, IL-6, TNF-R II, TGFβ1, HGF, OPN, OPG, FGF-23, TM, SDF1α, lower albumin and uric acid levels were observed in patients with PTX3 above the median. During follow-up, 27 patients (35%) died, including 25 due to CV causes. In contrast to CRP, baseline PTX3 predicted CV mortality independently of classical CV risk factors. Also, PTX3 concentrations significantly predicted mortality after adjustment for age, baseline dialysis status, serum OPG and CRP, radial artery calcifications, and CCA-IMT. CONCLUSIONS We postulate that PTX3 might be an early marker of CV mortality in patients with advanced CKD yet before the increase of specific marker for systemic inflammation like hsCRP.

Macrophages have established roles supporting bone formation. Despite their professional phagocytic nature, the role of macrophage phagocytosis in bone homeostasis is not well understood. Interestingly, apoptosis is a pivotal feature of cellular regulation and the primary fate of osteoblasts is apoptosis. Efferocytosis (phagocytosis of apoptotic cells) is a key physiologic process for the homeostasis of many tissues, and is associated with expression of osteoinductive factors. To test effects of macrophage depletion and compromised phagocytosis on bone, 16-week-old male C57BL/6J mice were treated with trabectedin-a chemotherapeutic with established anti-macrophage effects. Trabectedin treatment reduced F4/80+ and CD68+ macrophages in the bone marrow as assessed by flow cytometry, osteal macrophages near the bone surface, and macrophage viability in vitro. Trabectedin treatment significantly reduced marrow gene expression of key phagocytic factors (Mfge8, Mrc1), and macrophages from treated mice had a reduced ability to phagocytose apoptotic mimicry beads. Macrophages cultured in vitro and treated with trabectedin displayed reduced efferocytosis of apoptotic osteoblasts. Moreover, efferocytosis increased macrophage osteoinductive TGF-β production and this increase was inhibited by trabectedin. Long-term (6-week) treatment of 16-week-old C57BL/6J mice with trabectedin significantly reduced trabecular BV/TV and cortical BMD. Although trabectedin reduced osteoclast numbers in vitro, osteoclast surface in vivo was not altered. Trabectedin treatment reduced serum P1NP as well as MS/BS and BFR/BS, and inhibited mineralization and Runx2 gene expression of osteoblast cultures. Finally, intermittent PTH 1-34 (iPTH) treatment was administered in combination with trabectedin, and iPTH increased trabecular bone volume fraction (BV/TV) in trabectedin-treated mice. Collectively, the data support a model whereby trabectedin significantly reduces bone mass due to compromised macrophages and efferocytosis, but also due to direct effects on osteoblasts. This data has immediate clinical relevance in light of increasing use of trabectedin in oncology. © 2017 American Society for Bone and Mineral Research.

OBJECTIVE

To examine the prevalence and risk factors for hypercalcemia among non-dialysis chronic kidney disease (CKD) patients with mineral and bone disorder (MBD).

METHODS

A retrospective cohort study was conducted in Singapore General Hospital, involving all CKD stage 4 and 5 pre-dialysis patients who were on treatment for MBD in June 2016. Each patient was followed up for 1 year and screened for hypercalcemia episodes. Mild, moderate and severe hypercalcemia were defined as corrected calcium of 2.47-3.00, 3.01-3.50 and ≥ 3.51 mmol/l respectively. Patients who were on dialysis, post-renal transplant, post-parathyroidectomy or had no calcium levels taken during the study period were excluded. Details related to patients' clinical information and hypercalcemia episodes were collected. Multivariate logistic regression analysis was performed to evaluate risk factors for hypercalcemia.

RESULTS

Of 557 patients, 75 (13.4%) patients developed hypercalcemia. There were 120 (97.6%) mild and 3 (2.4%) moderate hypercalcemia episodes. The daily elemental calcium intake from phosphate binders and usage of vitamin D analogues did not differ between patients with and without hypercalcemia (p>> 0.05). After adjusting for covariates, lower baseline iPTH level [odds ratio (OR) 0.96, 95% CI 0.93-0.99], history of hypercalcemia in past 1 year (OR 11.11, 95% CI 3.36-36.75) and immobility (OR 3.34, 95% CI 1.34-8.40) were associated with increased hypercalcemia risk.

CONCLUSIONS

Hypercalcemia affects a significant proportion of pre-dialysis patients with MBD. More studies should be undertaken to evaluate other risk factors associated with hypercalcemia.

Intermittent parathyroid hormone (iPTH) treatment induces bone anabolic effects that result in the recovery of osteoporotic bone loss. Human PTH is usually given to osteoporotic patients because it induces osteoblastogenesis. However, the mechanism by which PTH stimulates the expansion of stromal cell populations and their maturation toward the osteoblastic cell lineage has not be elucidated. Mouse genetic lineage tracing revealed that iPTH treatment induced osteoblastic differentiation of bone marrow (BM) mesenchymal stem and progenitor cells (MSPCs), which carried the leptin receptor (LepR)-Cre. Although these findings suggested that part of the PTH-induced bone anabolic action is exerted because of osteoblastic commitment of MSPCs, little is known about the in vivo mechanistic details of these processes. Here, we showed that LepR⁺ MSPCs differentiated into type I collagen (Col1)⁺ mature osteoblasts in response to iPTH treatment. Along with osteoblastogenesis, the number of Col1⁺ mature osteoblasts increased around the bone surface, although most of them were characterized as quiescent cells. However, the number of LepR-Cre-marked lineage cells in a proliferative state also increased in the vicinity of bone tissue after iPTH treatment. The expression levels of SP7/osterix (Osx) and Col1, which are markers for osteoblasts, were also increased in the LepR⁺ MSPCs population in response to iPTH treatment. In contrast, the expression levels of Cebpb, Pparg, and Zfp467, which are adipocyte markers, decreased in this population. Consistent with these results, iPTH treatment inhibited 5-fluorouracil- or ovariectomy (OVX)-induced LepR⁺ MSPC-derived adipogenesis in BM and increased LepR⁺ MSPC-derived osteoblasts, even under the adipocyte-induced conditions. Treatment of OVX rats with iPTH significantly affected the osteoporotic bone tissue and expansion of the BM adipose tissue. These results indicated that iPTH treatment induced transient proliferation of the LepR⁺ MSPCs and skewed their lineage differentiation from adipocytes toward osteoblasts, resulting in an expanded, quiescent, and mature osteoblast population. © 2019 American Society for Bone and Mineral Research.

Mineral and bone disorders frequently cause cardiovascular complications and mortality in hemodialysis patients, but few observational studies of Japanese patients have investigated this matter. A retrospective cohort study of 99 patients (53 males, 46 females; mean age: 65 +/- 12 year; 38% with diabetes mellitus) on maintenance hemodialysis in our dialysis center was conducted. Mean serum Ca, P and intact parathyroid hormone (iPTH) levels were 9.2 +/- 0.9 mg/dL, 6.1 +/- 1.7 mg/dL, and 233 +/- 333 pg/mL, respectively. The cutoff values for each of these three parameter were defined according to the target ranges recommended by the Japanese Society for Dialysis Therapy (JSDT) guidelines (Ca: 8.4-10.0 mg/dL; P: 3.5-6.0 mg/dL; iPTH: 60-180 pg/mL). During a 45-month follow up, patients with all parameters outside the target ranges showed the highest incidence of cardiovascular events and all-cause deaths (16.6 and 29.2 per 1000 person-years, respectively). The relative risks of cardiovascular events and all-cause deaths were analyzed by multivariate Cox regression models. The hazard ratio (HR) for cardiovascular events was significantly lower for patients who achieved serum Ca and P objectives compared with others (HR: 2.12; 95% CI: 1.04-4.34; P < 0.05), and similar differences were observed for all-cause deaths (HR: 3.10; 95% CI: 1.13-8.53; P < 0.05). However, the relationship between iPTH levels and each of the endpoints was less pronounced. The results of this study provide support for the JSDT guidelines, which give priority to the control of serum Ca and P levels over the control of parathyroid function.

BACKGROUND

Poor medication adherence is a frequent cause of treatment failure but is difficult to diagnose. In this study we have evaluated the impact of measuring adherence to cinacalcet-HCl and phosphate binders in dialysis patients with uncontrolled secondary hyperparathyroidism.

METHODS

7 chronic dialysis patients with iPTH-levels>>= 300 pg/ml despite treatment with>>= 60 mg cinacalcet-HCl were included. Medication adherence was measured using the "Medication Events Monitoring System" during 3 months, followed by another 3-month period without monitoring. The adherence results were monthly discussed with the patients, as well as strategies to improve them.

RESULTS

During monitoring, the percentage of prescribed doses taken was higher for cinacalcet-HCl (87.4%) and sevelamer (86.3%) than for calcium acetate (76.1%), as was the taking adherence (81.9% vs. 57.3% vs. 49.1%) but not the percentage of drug holidays (12.3% vs. 4.5% vs. 3.6%). Mean PO4 levels (from 2.24 +/- 0.6 mmol/l to 1.73 +/- 0.41 mmol/l; p = 0.14) and Ca++ x PO4 product (4.73 +/- 1.43 to 3.41 +/- 1.04 mmol2/l2; p = 0.12) improved and iPTH-level improved significantly from 916 +/- 618 pg/ml to 442 +/- 326 pg/ml (p = 0.04), without any change in medication. However, as drug monitoring was interrupted, all laboratory parameters worsened again.

CONCLUSIONS

Assessment of drug adherence helped to document episodes of non-compliance and helped to avoid seemingly necessary dose increases.

OBJECTIVE

Uremic hyperparathyroidism (UHPT) has been shown to contribute to the development and progression of chronic kidney disease-mineral bone disorder. UHPT is frequently observed in chronic dialysis patients, and patients with UHPT are associated with increased risk of all-cause and cardiovascular mortality. Cinacalcet is a novel agent that increases sensitivity to the calcium-sensing receptor and is approved for control of UHPT. Nevertheless, cinacalcet is costly and information regarding efficacy of low-dose cinacalcet on UHPT is limited.

METHODS

We conducted a retrospective study to evaluate treatment with either low-dose calcitriol combined with low-dose cinacalcet (25 mg) (d-cinacalcet) or calcitriol alone (VitD) in dialysis patients with moderate to severe UHPT. A total of 81 dialysis patients were enrolled (40 subjects in d-cinacalcet group and 41 subjects in VitD group). Demographic data including age, gender, duration on dialysis and biochemical data were reviewed and recorded.

RESULTS

At the end of the study, the intact parathyroid hormone (iPTH) levels of the d-cinacalcet group declined significantly (from 1166.0 ± 469.3 pg/mL to 679.8 ± 421.6 pg/mL, p < 0.0001), while there was no significant change in the VitD group. Significant decrease of serum calcium (Ca: 9.9 ± 0.6 mg/dL vs. 9.6 ± 0.8 mg/dL, p = 0.002), phosphorus (P: 5.9 ± 1.3 mg/dL vs. 4.9 ± 0.9 mg/dL, p < 0.0001) and calcium phosphate product (Ca × P: 58.7 ± 15.0 mg2/dL2 vs. 46.9 ± 8.9 mg2/dL2, p < 0.0001) were observed in the d-cinacalcet group. In addition, the subjects in the d-cinacalcet group had a greater proportion to achieve Kidney Disease Outcomes Quality Initiative (KDOQI)-recommended biochemical targets than the subjects in the VitD group (Ca: 48% vs. 24%; P: 78% vs. 32%; Ca × P: 85% vs. 37%; iPTH: 15% vs. 0%).

CONCLUSIONS

We conclude that combination therapy of low-dose cinacalcet and calcitriol is more effective than calcitriol alone as a treatment for moderate and severe UHPT in chronic dialysis patients. Furthermore, this therapy is associated with improvement in hyperphosphatemia and hypercalcemia.

Secondary hyperparathyroidism (SHPT) is a common complication in chronic renal disease. Osteoprotegerin (OPG), an extracellular cytokine receptor secreted by osteoblasts, can promote bone formation by inhibiting the function of osteoclasts. Hemodialysis (HD) patients have elevated serum OPG levels. OPG secretion can be suppressed with high parathyroid hormone (PTH) levels. HD patients with refractory SHPT can benefit from parathyroidectomy (PTX) treatment, but the changes of serum OPG, bone turnover markers and bone mineral density (BMD) following PTX in HD patients remain unclear. In this study, patients on maintenance HD who received PTX for refractory SHPT (n = 28) were prospectively followed for 1 year. Serum intact PTH (iPTH), alkaline phosphatase (Alk-P), and OPG were measured serially; BMD was measured pre-PTX and at 1 year after PTX. After PTX, serum iPTH levels reduced profoundly. Serum Alk-P levels increased rapidly, peaking at 2 weeks post-PTX, while serum OPG levels gradually increased at 2 weeks after PTX and peaked at 2 months. BMD improved in both femoral neck (FN; cancellous and cortical bone) and lumbar spine (LS; cancellous bone). Higher baseline iPTH levels were associated with greater FN and LS BMD improvements at one year after PTX. The increment of serum OPG was correlated with the increase in LS BMD, implying that inhibition of osteoclastic bone resorption may improve BMD within the first year after PTX. These findings suggest that PTX removes the suppressive effects of high PTH on OPG secretion, resulting in the increased serum OPG levels that may contribute to BMD improvement.