OBJECTIVE

The COBAS Elecsys PTH(1-84) assay is a novel, electro-chemiluminescence immunoassay that exclusively measures full-length parathyroid hormone (PTH). The aim of this study is to compare the automated biointact Elecsys PTH(1-84) assay with four contemporary, iPTH assays in chronic kidney disease (CKD) patients.

METHODS

We compared the Elecsys PTH(1-84) assay with four iPTH assays (Siemens ADVIA Centaur, Ortho Clinical Diagnostics (OCD) VITROS, Beckman Access2, Abbott ARCHITECT) in the measurement of PTH in 83 local CKD patients. Majority of the patients (44) had CKD but were not on dialysis, 15 were on hemodialysis, 15 were on peritoneal dialysis, and 9 were post-renal transplant. The precision performance and correlation of the assays were determined. PTH(1-84) concentrations were correlated with calcium, phosphate, alkaline phosphatase, hemoglobin, HbA1c and lipid concentrations.

RESULTS

The Elecsys PTH(1-84) assay showed comparable precision and good correlation with the iPTH assays. Although the four different iPTH assays correlated well with each other, there was significant discrepancy among assays. The discrepancy among assays increased with increasing PTH concentrations. The ADVIA Centaur and ARCHITECT assays measured significantly higher PTH concentrations than the VITROS and Access2 assays. PTH(1-84) showed a positive association with phosphate and alkaline phosphatase and an inverse association with HbA1c. There was no significant association with lipid concentrations.

CONCLUSIONS

The third generation Elecsys PTH(1-84) assay had comparable precision performance and correlated well with second generation iPTH assays. However, significant discrepancy was found among the four iPTH assays in measuring iPTH in CKD patients.

BACKGROUND

End stage renal disease (ESRD) patients on renal replacement therapy (RRT) with diabetes mellitus (DM) have a higher mortality rate and an increase prevalence of vitamin D deficiency compared to those without DM. It is still debated if vitamin D deficiency is a risk factor or a prognostic marker for mortality in these patients. This study investigated the prevalence of vitamin D deficiency and its impact on all-cause mortality in HD patients with DM.

METHODS

Our prospective non-interventional cohort study included 600 patients on hemodialysis therapy (HD) (median aged 56, interquartile range (19) years, 332 (55.3%) males) recruited from 7 HD centers, from all main geographical regions of Romania. The prevalence of DM was 15.3%. They were then followed regarding: dialysis duration, dialysis efficiency, renal anemia, CKD-MBD, inflammatory status and comorbidities: coronary artery disease (CAD), peripheral vascular disease (PVD) and stroke. The deficiency of 25-OH vitamin D was defined as a value lower than 12 ng/mL.

RESULTS

Patients were followed for 3 years. The overall 3 year mortality was 25.5% (153 individuals), being higher in patients with DM as compared to those without DM (33.7% vs. 24.0%; P = 0.049). The time-related prognosis was also influenced by the presence of DM, at the survival analysis resulting in a HR of 1.52 [1.03 to 2.26] 95% CI, P = 0.037, for death in dialyzed patients with DM. In DM patients, 25-OH vitamin D deficiency was significantly higher (37.0% compared to 24.0%, P = 0.009). Furthermore, in patients with DM we observed a shorter dialysis duration (2 vs. 3 years, P<0.001) and a lower intact parathyroid hormone (iPTH) (258.0 pg/ml vs. 441.9 pg/ml, P = 0.002). Regarding the presence of comorbidities at the inclusion in the study, the presence of diabetes in dialyzed patients was associated with increased prevalence of CAD (87.0% vs. 58.1%, P<0.001), PVD (67.4% vs. 17.3%, P<0.001) and history of stroke (29.3% vs. 14.0%, P<0.001). In patients with DM the presence of 25-OH vitamin D deficiency increased the probability of death (50.0% vs. 24.1%; P = 0.011). In multiple Cox proportional hazards analysis, vitamin D deficiency remained an independent predictor for mortality in dialysis patients with DM (HR = 1.71, 95% CI 1.21 to 2.43, P = 0.003). In the same time, multiple Cox proportional hazards analysis showed that age (HR = 1.02 per one year increase, P = 0.004), CAD (HR = 1.55, P = 0.046) and PVD (HR = 1.50, P = 0.029) were independent predictors for mortality in dialysis patients with DM.

CONCLUSIONS

ESRD patients with DM treated with HD have a higher overall mortality than non-DM patients. Vitamin D deficiency is significantly more prevalent in HD patients with DM. Low 25-OH vitamin D levels were associated with increased all-cause mortality in these patients. According to our data, in HD patients with DM, screening for vitamin D deficiency (and its correction) should be mandatory for an optimal risk reduction strategy.

BACKGROUND

Tertiary hyperparathyroidism continues to cause significant morbidity in patients with chronic renal failure. This is frequently resistant to medical management and may ultimately require a surgical parathyroidectomy. Recent studies have reported upon the technique of percutaneous ethanol ablation for both primary and tertiary hyperparathyroidism. In this study we report on a 5 year experience using ethanol injection and compare the results with surgical parathyroidectomy.

METHODS

A prospective study in 39 patients with tertiary hyperparathyroidism, 25 were dialysis dependent and 14 had a functioning renal allograft. Twenty-two patients underwent percutaneous fine needle ethanol injection (PFNEI) and 17 underwent surgical parathyroidectomy.

RESULTS

A>> 30% reduction in intact parathyroid hormone (iPTH) was achieved in 11 of 22 patients undergoing PFNEI after a mean of 1.8 +/- 1.4 injections per gland. In four patients, symptomatic hyperparathyroidism recurred and they required further PFNEI or surgical parathyroidectomy at 17, 28, 46, and 48 months later. There was no significant reduction in iPTH in 11 patients following PFNEI after a mean of 2.5 +/- 1.3 injections per gland. They all required a subsequent surgical parathyroidectomy for symptomatic hyperparathyroidism. Four patients developed a laryngeal nerve palsy following PFNEI, two of which were permanent. Seventeen patients underwent successful surgical parathyroidectomy as a primary procedure.

CONCLUSIONS

Whilst PFNEI is successful in primary hyperparathyroidism, when typically only one adenoma is present, the effectiveness of PFNEI is unpredictable and the long term results are poor compared with those of surgical parathyroidectomy in tertiary hyperparathyroidism. The procedure is not without complications and makes subsequent surgery more difficult. Therefore it can only be recommended for patients with a known single parathyroid gland such as patients in whom hyperparathyroidism has recurred following a previous surgical subtotal parathyroidectomy and who are unsuitable for further surgery.

Prevalence of adynamic bone disease (ABD), characterized by low bone turnover and absence or a reduced number of osteoblasts and osteoclasts, is increasing steadily over the last years. We present a dialysis patient, with recurrent bone fractures and biopsy-proven ABD, who was treated with teriparatide. Nine months after initiation of treatment, iPTH plasma levels increased to 520 pg/mL and a second bone biopsy revealed high bone turnover, normal mineralization and normal bone volume. Two years later, iPTH was 250-350 pg/dL and bone metabolism parameters within normal range. The probable utility of teriparatide in the treatment of ABD in dialysis patients is discussed.

The vitamin D hormone, [1,25(OH) 2D, calcitriol], inhibits proliferation and angiogenesis in breast cancer but its therapeutic use is limited by hypercalcemia. Synthetic analogs of 1,25(OH) 2D that are less calcemic, such as paricalcitol (19-nor-1,25-Dihydroxyvitamin D 2), are used to treat hyperparathyroidism associated with chronic kidney disease. We sought to determine the safety and feasibility of taking oral paricalcitol with taxane-based chemotherapy in women with metastatic breast cancer (MBC). Oral paricalcitol was considered safe if it did not result in excessive toxicity, defined as grade 3 or higher serum calcium levels. It was considered feasible if the majority of women could take eight weeks of continuous therapy in the first three months. Serum calcium was monitored weekly and the paricalcitol dose was adjusted based on its calcemic effect. Intact parathyroid hormone (iPTH) was monitored as a marker of paricalcitol activity. Twenty-four women with MBC were enrolled. Twenty women (83%) received eight weeks of continuous therapy. Paricalcitol was well-tolerated with no instances of hypercalcemia grade 2 or greater. Fourteen women (54%) were able to escalate the dose. The dose range of paricalcitol in the first 3 mo was 2-7 ug/day. Serum iPTH levels at baseline were significantly higher in women with serum 25-Hydroxyvitamin D (25-OHD) levels less than 30 ng/ml (96.4 ± 40.9 pg/ml) vs. 46.2 ± 20.3 pg/ml (p = 0 0.001) (iPTH reference 12-72 pg/ml). We conclude that paricalcitol is safe and feasible in women with MBC who are receiving chemotherapy.

BACKGROUND

Hyperkalemia is prevalent in end-stage renal disease patients, being involved in life-threatening arrhythmias. Although polystyrene sulfonate (PS) is commonly used for the treatment of hyperkalemia, direct comparison of effects between calcium and sodium PS (CPS and SPS) on mineral and bone metabolism has not yet been studied.

METHODS

In a randomized and crossover design, 20 pre-dialysis patients with hyperkalemia (>5 mmol/l) received either oral CPS or SPS therapy for 4 weeks.

RESULTS

After 4-week treatments, there was no significant difference of changes in serum potassium (K) from the baseline (ΔK) between the two groups. However, SPS significantly decreased serum calcium (Ca) and magnesium (Mg) and increased intact parathyroid hormone (iPTH) values, whereas CPS reduced iPTH. ΔiPTH was inversely correlated with ΔCa and ΔMg (r = -0.53 and r = -0.50, respectively). Furthermore, sodium (Na) and atrial natriuretic peptide (ANP) levels were significantly elevated in patients with SPS, but not with CPS, whereas ΔNa and ΔANP were significantly correlated with each other in all the patients. We also found that ΔNa and Δ(Na to chloride ratio) were positively correlated with ΔHCO3-. In artificial colon fluid, CPS increased Ca and decreased Na. Furthermore, SPS greatly reduced K, Mg, and NH3.

CONCLUSIONS

Compared with SPS, CPS may be safer for the treatment of hyperkalemia in pre-dialysis patients, because it did not induce hyperparathyroidism or volume overload.

BACKGROUND

We assessed the need of vitamin D supplementation to achieve normal 25-hydroxyvitamin D (25[OH]D) levels after bariatric surgery and whether there were differences between laparoscopy sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB).

METHODS

A total of 164 morbid obese patients undergoing bariatric surgery from January 2008 to June 2011 were followed for 2 years. Serum levels of 25(OH)D and intact parathyroid hormone (iPTH) were measured preoperatively and at 3, 6, 9, 12, 18, and 24 months after operation. All patients received 400 IU/day of 25(OH)D. Patients received additional supplementation with 16,000 IU of vitamin D3 (calcifediol) every 2 weeks if 25(OH)D serum levels were < 30 ng/mL (intervention group).

RESULTS

Ninety-six (58.5 %) patients underwent LSG and 68 (41.5 %) LRYGB. A total of 106 (64.6 %) patients received calcifediol supplementation (62 in the LSG group and 44 in the LRYGB group). Normal 25(OH)D levels at 24 months were recorded in 69 % of patients in the intervention group and in 48.3 % in the non-intervention group. At 24 months, mean 25(OH)D levels in the non-intervention group were significantly lower among LRYGB patients than among LSG patients (P = 0.009). In the intervention group, normal 25(OH)D levels were achieved in 60 % of patients treated with LSG and in 22.2 % of those treated with LRYGB. Secondary hyperparathyroidism was presented in 49 (29.9 %) patients preoperatively but without significant differences in iPTH levels between the two surgical procedures.

CONCLUSIONS

Patients undergoing bariatric surgery should receive high-dose vitamin D supplementation independently of the surgical technique.

Vitamin D deficiency is a common problem, and it is related to increased risk of obesity, metabolic syndrome, atherosclerosis, and cardiovascular disease. Vitamin D has a beneficial effect on dyslipidemia and insulin secretion. We aimed to investigate the impact of vitamin D₃ supplementation on anthropometric and laboratory parameters in overweight and obese premenopausal women.

Seventy-two overweight and 50 obese vitamin-D-deficient premenopausal women (mean age: 43.1 ±10.4 years) were included in the study. Baseline mean 25-hydroxyvitamin D [25(OH)D] level was 6.1 (min.-max. = 2.9-15.8) ng/ml in overweight and was 5.6 (min.-max. = 3.0-22.0) ng/ml in obese subjects. At baseline and at the sixth month of supplementation, serum 25(OH)D, intact parathormone (iPTH), calcium, phosphorus, homeostasis model assessment of insulin resistance (HOMA-IR), and lipid profiles were assessed.

Results

Following vitamin D₃ supplementation in overweight and obese subjects, serum 25(OH)D increased from 6.1 to 34.7 ng/ml and 5.6 to 34.7 ng/ml, respectively (p < 0.001). At the sixth month of supplementation in both overweight and obese subjects, a significant reduction was detected in HOMA-IR (p < 0.001), low-density lipoprotein cholesterol (LDL-C) (p = 0.046, p = 0.044; respectively) and iPTH levels (p ≤ 0.001, p < 0.001; respectively). A negative adjusted correlation was found between changes in 25(OH)D and HOMA-IR (r = -0.581, p < 0.001; r = -0.389, p = 0.005; respectively). A 1 ng/ml increase in serum 25(OH)D level led to a 0.30-fold reduction in HOMA-IR level (p = 0.002).

Conclusions

Our results support the effect of vitamin D₃ supplementation in HOMA-IR and LDL-C improvement in both obese and overweight subjects. Further studies focused on low serum 25(OH)D levels with insulin resistance and dyslipidemia are needed.

Twenty-seven normocalcemic patients aged 11-69 yrs with recurrent renal stone formation and idiopathic hypercalciuria were studied before and after treatment with hydrochlorthiazide (TD) 50 mg twice a day for 6 months. Hypercalciuria was defined as a 24 h renal calcium excretion of more than 7.5 mmol for males and 6.3 mmol for females. Quantitative histomorphometric analysis of iliac crest bone biopsies were performed before and after treatment. TD treatment increased the adjusted serum calcium level (p less than 0.01), whereas no significant effects on the serum levels of phosphorous, alkaline phosphatase or iPTH were found. The urinary calcium/creatinine ratio decreased (p less than 0.01) during TD treatment, whereas no change in the urinary phosphorous/creatinine ratio was found. The histomorphometric analysis revealed a reduction in the extent of eroded surfaces (p less than 0.05) and bone formation rate (p less than 0.05) as well as a decrease in the osteoid thickness (p less than 0.05) during TD treatment. No effect on the trabecular bone volume was found. A reduction in the activation frequency of new remodeling sites and thereby a reduced bone turnover during TD treatment can explain the observed histomorphometric changes. The decrease in osteoid thickness may be related to the increased serum calcium concentration leading to better conditions for mineralization.

Obesity is associated with altered bone mass. However, reports on bone status in obesity are inconsistent. Increased or normal bone mass was reported in obese adults but decreased bone mineral content was described in obese children. Therefore we evaluated the obese fa/fa rat as a possible model to assist in studies of bone metabolism in obesity. Obese and lean 14-week-old male rats underwent 24 h balance studies for calcium, magnesium and phosphate. Plasma calcium, magnesium, phosphate, immunoreactive parathyroid hormone, urinary cAMP (cyclic adenosine monophosphate) and femur bone histomorphometry were also analysed. Obese rats were heavier and had higher plasma insulin, cholesterol and triglycerides levels (P less than 0.05). A comparable positive balance for calcium, magnesium and phosphate was found in obese and lean rats. Total plasma calcium was higher in the obese, but albumin corrected calcium and plasma magnesium, phosphate and glucose were similar to the lean. In contrast to human obesity, obese rats were hypercalciuric, hypermagnisuric and hyperphosphaturic (P less than 0.05). iPTH and urinary cAMP were higher in the obese. Femora of fa/fa rats were shorter and lighter. Their bone osteoid surface and bone calcium content were similar to controls. Femora metaphysis in the obese had increased number of trabeculae, decreased trabecular width and higher erosion surface/bone surface ratio. Their diaphysis had increased cortical area/bone area and cortical width/bone width ratios and decreased medullary area. In summary, obese rats have higher iPTH, are hypercalciuric and have decreased bone mass. These last two observations differ from what is described in adult human obesity. Therefore, the obese fa/fa rat is of limited assistance in studies of bone status in adult human obesity. It might be of help in studies of bone metabolism in juvenile obesity.

OBJECTIVE

Fibroblast growth factor 23 (FGF23) is a phosphaturic agent involved in calcium-phosphate homeostasis. Recent findings show that iron deficiency and inflammation regulate FGF23 release and/or biodegradation. Iron deficiency is frequently observed in the elderly, therefore the aim of this study was to find out if iron deficiency is independent from low grade inflammatory factors affecting both forms of FGF23 that are detectable in circulation in a large population-based study of elderly subjects.

METHODS

The analysis included 3780 elderly (1798 females) PolSenior study participants and assessed levels of phosphorus, calcium, iron, ferritin, interleukin 6, C-reactive protein (hs-CRP), intact (iFGF23), and c-terminal FGF (cFGF23). The analysis was performed for all subjects and terciles of serum iron levels in relation to hs-CRP were calculated.

RESULTS

The highest plasma cFGF23 and iFGF23 concentrations were found in subjects with the lowest serum iron levels (p<0.001). The effect of low grade inflammation was markedly weaker and affected only iFGF23 levels. The adjusted serum levels of hs-CRP, iPTH, phosphorus, and 25-(OH)-D3 analysis revealed that plasma iFGF23 and cFGF23 levels were almost unchanged up to a serum iron level of 59.3 ng/mL and 57.3 ng/mL respectively and then were nearly linearly increasing by 0.285 pg/mL and 3.742 RU/mL for each unit of serum iron increase.

CONCLUSIONS

Low iron levels are associated with increased levels of both cFGF23 and iFGF23, independent of low grade inflammation. A similar analysis of cFGF23 and iFGF23 does not suggest enhanced biodegradation of iFGF23 induced by iron deficiency.

Patients with end-stage renal disease (ESRD) are at an increased risk of cardiovascular disease due to many factors including inflammation and oxidative stress. N-acetylcysteine (NAC) is a thiol-containing anti-oxidant with anti-inflammatory properties. We aimed to assess the effect of three months treatment with oral NAC on the plasma levels of inflammatory mediators like interleukin-6 (IL-6) and C-reactive protein (hs-CRP) in patients on hemodialysis (HD). Twenty-four patients (nine males and 15 females) on maintenance HD were recruited in the study. Their mean age was 55.3 years. All the patients received oral NAC (600 mg twice a day) for a period of three months. The serum levels of biomedical parameters and IL-6 and hs-CRP were measured at baseline and three months after initiation of treatment. A significant decrease in serum levels of hs-CRP (22.4 vs. 5.2), IL-6 (8.1 vs. 3.6), parathyroid hormone (iPTH) (257.2 vs. 158.8), ferritin (632.0 vs. 515.1) and erythrocyte sedimentation rate (ESR) (54.2 vs. 38.3) was observed following NAC treatment. Female subjects presented with a significantly higher change in serum levels of hs-CRP compared with males (23 vs. 5.4). In three subjects who were less than 40 years old, the hs-CRP and IL-6 levels showed an increase following NAC treatment. Our study found that short-term oral NAC treatment might result in the reduction of IL-6 and hs-CRP in patients who are on regular HD. This suggests that patients with ESRD may benefit from the anti-inflammatory effects of NAC.

BACKGROUND

The standard surgical procedure for parathyroidectomy consists of bilateral cervical exploration and the visualization of all four parathyroid glands. However, improved preoperative localization techniques and the availability of intraoperative intact parathyroid hormone (iPTH) monitoring now allow single adenomas to be treated with minimally invasive techniques.

METHODS

Patients with primary hyperthyroidism (pHPT), who were found to have one unequivocally enlarged parathyroid gland on preoperative ultrasound and 99mTc-SestaMIBI scintigraphy underwent minimally invasive video-assisted parathyroidectomy by an anterior approach. Intraoperatively, rapid electrochemiluminescense immunoassay was used to measure iPTH levels shortly before and 5, 10, and 15 mins after excision of the adenoma. The operation was considered successful when a >50% decrease in preexcision iPTH levels was observed after 5 min.

RESULTS

Between November 1999 and May 2000, 10 of 22 patients with pHPT were deemed eligible for the minimally invasive approach. In all cases, the adenoma was removed successfully. However, in two cases, intraoperative iPTH monitoring did not show a sufficient decrease in iPTH values. Subsequent cervical exploration revealed a double adenoma in one case and hyperplasia in the other.

CONCLUSIONS

Even when high-resolution ultrasound and 99mTc-SestaMIBI scintigraphy are used, the presence of multiple glandular desease cannot be ruled out entirely. When the minimally invasive approach is contemplated, intraoperative iPTH monitoring is indispensible to ensure operative success. However, in selected cases, minimally invasive parathyroidectomy represents an excellent alternative to the conventional technique.

The relationships between nutritional factors, calcium regulating hormones, and bone density were evaluated in three groups of normal subjects in rural southeast Kansas. Dietary intake of calcium (Ca), phosphorous (P), protein, and vitamin D; and serum 25OHD, Ca, P, parathyroid hormone (iPTH), and bone density (distal 1/3 radius) were measured in 29 elderly women, 35 elderly men, and 50 perimenopausal women. Measurements were repeated 5 years and 4 years later respectively in 16 elderly women and 15 elderly men. The r values for significant regression correlations for each group were as follows: perimenopausal: bone density and dietary Ca:P--r = .29, iPTH and 25OHD--r = -.38; elderly women: 25OHD and dietary Vitamin D(D)--r = .58, change in bone density (delta BD) and initial bone density (BDI)--r = -.71, delta BD and serum 25OHD--r = -.60, serum calcium and age--r = -.42; elderly men: Serum 25OHD and D--r = .61, iPTH and 25OHD--r = -.43, iPTH and serum phosphorous--r = .59.

CONCLUSIONS

The more adequate the state of vitamin D nutriture, the lower the serum iPTH in perimenopausal women and elderly men and the less bone loss in elderly women. The Ca:P ratio in the diet may be important in maintaining bone density in perimenopausal women.

BACKGROUND Impaired renal function is common among older patients. Deficiency of vitamin D is a frequent phenomenon among patients with impaired renal function, who are likely to develop cardiovascular diseases. This study aimed to explore the association of 25 (OH) D levels with left ventricular mass and arterial stiffness in older patients with impaired renal function. MATERIAL AND METHODS Based on their admission estimate glomerular filtration rate (eGFR), 273 inpatients (≥65 years) were allocated into a normal eGFR group (≥60 ml/min) and an impaired eGFR group (<60 ml/min). The 25 (OH) D levels were measured and the left ventricular mass index (LVMI) was estimated. Pulse wave velocity (PWV) was used to explore arterial stiffness. RESULTS The 25 (OH) D levels of patients in the impaired eGFR group were significantly lower than in the normal eGFR group [(11.92±6.01) μg/L vs. (18.14±8.07) μg/L, p<0.05). LVMI and PWV were both significantly higher in the impaired eGFR group than in the normal eGFR group [(104.89±33.50) g/m2 vs. (92.95±18.95) g/m2, P<0.05; (15.99±3.10) m/s vs. (13.62±2.90) m/s, P<0.05]. After adjusting for age, sex, eGFR, cardiovascular risk factors, serum calcium, and iPTH levels, the inverse association between LVMI and 25 (OH) D, PWV, and 25 (OH) D were statistically significant. CONCLUSIONS Vitamin D level is lower in older patients with impaired renal function. Lower vitamin D levels were correlated with higher left ventricular mass and increased arterial stiffness in older patients.

This report describes acute studies of parathyroid hormone (PTH) secretion and metabolism in conscious dogs, performed with a new technique, the "calcium clamp." Bolus injections and graded infusions of either calcium (Ca) or EGTA, respectively, increase or decrease plasma Ca to desired levels in 1-2 min; rapid determination of plasma Ca permits feedback control of the infusion rates to maintain the desired Ca concentration for prolonged periods. Using this technique, we have examined the effect in five dogs of a sustained (1 h) decrease in plasma Ca from 9.6 to 7.6 mg/dl on the secretion of PTH. Plasma immunoreactive PTH (IPTH) concentration in precaval blood increased within 1 min, peaked at 4-10 min (greater than 5 times control), but thereafter declined gradually to 57% of the maximum at 60 min, despite ongoing and constant hypocalcemia. Abrupt restoration of normocalcemia caused IPTH levels to decrease with an apparent half-time of 3.0 +/- 0.3 min (mean +/- SE). Thus, external feedback-regulated control of plasma Ca is possible in experimental animals. IPTH concentrations decline from the maximum during constant hypocalcemia, a new observation that suggests that PTH secretion and/or metabolism are altered progressively by the hypocalcemia.

The effects of pregnancy and lactation on endosteal bone formation and resorption were evaluated in vitamin D-depleted (-D) and vitamin D-repleted (+D) rats. Pregnancy induced a marked stimulation of osteoclastic bone resorption and of static and dynamic parameters of bone formation and mineralization. Bone resorption increased independently of vitamin D status and did not correlate with plasma 1,25-dihydroxyvitamin D3 [1,25(OH)2D] levels, but it was associated with increased plasma immunoreactive parathyroid hormone (iPTH) concentrations. Stimulation of the endosteal bone formation rate was mainly impaired in D-depleted rats, resulting in trabecular bone loss, which, in -D mother rats, was associated with decreased bone ash and total bone calcium. Lactation further stimulated bone resorption and reduced the trabecular bone volume; ash weight and bone calcium content were also decreased independently of the vitamin D status and changes in plasma iPTH levels. In presence of vitamin D, the bone formation rate increased fourfold during lactation but was unchanged in -D lactating rats. During lactation, vitamin D-depleted rats lost twofold more calcified bone than +D rats because of impaired mineralization. Thus, the present study shows that both the endosteal bone resorption and formation are stimulated by pregnancy and lactation and that vitamin D is required for normal bone mineralization during the reproductive period.

OBJECTIVE

Primary hyperparathyroidism (PHPT) is associated with increased cardiovascular mortality and morbidity. Little is known about hemostatic features of patients with PHPT. To our knowledge, plasma tissue factor pathway inhibitor (TFPI) and thrombin-activatable fibrinolysis inhibitor (TAFI) levels in these patints have not been investigated. Therefore, the main purpose of this study was to evaluate the markers of endogenous coagulation/fibrinolysis, including TFPI and TAFI, and to investigate the relationships between serum calcium and PTH and these hemostatic parameters in patients with PHPT.

METHODS

Twenty-four patients with PHPT and 20 age-, sex-, and-weight-matched healthy controls were included in the study. Tissue plasminogen activator (t-PA), tissue plasminogen activator inhibitor-1 (PAI-1), TFPI, and TAFI were measured. The relationships between serum calcium, phosphorus, and PTH and these hemostatic parameters were examinated.

RESULTS

Compared with the control subjects, t-PA, PAI-1, and PAI-1/t-PA ratios were significantly increased in patients with PHPT (P<0.0001), whereas TFPI levels were significantly decreased (P<0.0001). Plasma TAFI Ag levels did not significantly change in patients with PHPT compared with the controls. In patients with PHPT, serum phosphorus was negatively correlated with plasma PAI-1 Ag levels and PAI-1/t-PA ratio (r: -0.453, P<0.05; r: -0.580, P<0.01 respectively). There was a positive correlation between Cl/P ratio and plasma PAI-1 levels and PAI-1/t-PA ratio (r: 0.434, P<0.05; r: 0.528, P<0.05 respectively). iPTH was positively correlated with plasma PAI-1/t-PA ratio (r: 0.429, P<0.05).

CONCLUSIONS

In conclusion, we found some important differences in the hemostatic parameters between the patients with PHPT and healthy controls. Increased PAI-1, PAI-1/t-PA ratios and decreased TFPI levels in these patients represent a potential hypercoagulable and hypofibrinolytic state, which might augment the risk for atherosclerotic and atherothrombotic complications. This condition may contribute to the excess mortality due to cardiovascular disease seen in patients with PHPT.

Parathyroid function was studied in two infant sisters with primary hypomagnesemia while they were both hypomagnesemic and hypocalcemic. In one of the infants, plasma immunoreactive parathyroid hormone (iPTH) was elevated, the calcemic response to exogenous parathyroid hormone (PTH) was absent, and the phosphaturic response was normal. Restoration of serum magnesium with i.v. magnesium corrected the hypocalcemia, with no further rise of plasma iPTH. In the other infant, plasma iPTH was undetectable, and exogenous PTH produced both phosphaturic and calcemic responses. Normalization of serum magnesium with i.v. magnesium resulted in a prompt release of endogenous PTH and correction of the hypocalcemia. These findings suggest that, in the first patient, hypocalcemia was associated with lack of response of the bone to both endogenous and exogenous PTH, while in the second patient, hypocalcemia was associated with inhibition of PTH release and a normal calcemic response to exogenous PTH. The factors that determine whether magnesium deficiency will result in inhibition of PTH release, in a lack of response of the bone to endogenous and exogenous PTH, or both, remain to be clarified.

A non-comparative study was conducted to examine the effects of 80,000 IU vitamin D given in a single dose to 59 pregnant women from northern or southern France between their 27th and 32nd week of gestation during the winter season. Serum levels of 25 hydroxy-vitamin D (25 OH D), intact Parathyroid Hormone (iPTH), calcium, phosphates, proteins were measured at the inclusion, at delivery (mother and arterial cord) and in the newborn between the 3rd and the 5th day of life. The mothers' sun exposure and their vitamin D dietary intakes were evaluated with scores at the inclusion and at delivery. Before vitamin D supplementation, 34% of the women had a 25 OH D concentration below 10 ng/ml and 32% had hypocalcemia. At delivery, only one woman had a low 25 OH D concentration, whereas 15% of the women showed hypocalcemia. No neonatal hypocalcemia was observed and no vitamin D overdose was recorded in this study. The mothers' vitamin D dietary intakes were quite high; the lack of sun exposure during last summer appeared as a major vitamin D deficiency risk. A single dose of 80,000 IU vitamin D, taken between the 27th and the 32nd amenorrhoea weeks in winter, seems to be a good compromise between efficacy and tolerance.

BACKGROUND

Accumulating evidence suggests that vitamin D deficiency is associated with increased risk of stroke. Contributing mechanisms have been linked to the association of vitamin D deficiency with the presence of hypertension, diabetes mellitus, and atherosclerosis, however, the evidence is conflicting.

OBJECTIVE

This study sought to determine the association of vitamin D deficiency with ischemic stroke and its risk factors.

METHODS

Cross-sectional case control study.

METHODS

We measured serum 25-hydroxyvitamin D [25(OH) D] and intact parathyroid hormone (iPTH) levels in 73 patients of ischemic stroke, presenting within 7 days of onset of stroke and compared with 70 age and gender matched controls.

METHODS

The statistical analysis was carried out using Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, version 17.0 for Windows).

RESULTS

The mean age of patients and controls was 59.9 ± 11.2 years and 57.9 ± 9.7 years, respectively (P = 0.26). Of 67.1% patients were men as compared to 65.7% controls (P = 0.86). There was no significant difference in the prevalence of vitamin D deficiency/insufficiency (P = 0.25), mean 25(OH) D levels (P = 0.75), and iPTH levels (P = 0.10) between cases and controls. No association of vitamin D deficiency/insufficiency was found with the prevalent risk factors in cases of ischemic stroke.

CONCLUSIONS

Vitamin D deficiency does not bear an association with ischemic stroke or its risk factors.

BACKGROUND

Considering the suggested link between vitamin D insufficiency and several chronic diseases, attention should be given to approaches for improving vitamin D status. Elderly subjects are regarded as a high-risk group for developing an insufficient vitamin D status. Socioeconomic, dietary, lifestyle and environmental factors are considered as influencing factors, whereupon sex differences in predictors of vitamin D status are rarely investigated. The purpose of this study is to identify the main predictors of serum 25-hydroxyvitamin D3 [25(OH)D3] concentrations in elderly subjects by taking into account potential sex differences.

METHODS

This is a cross-sectional study in 162 independently living German elderly aged 66 to 96 years. Serum 25(OH)D3 concentrations were assessed by an electrochemiluminescence immunoassay. Multiple regression analyses were performed to identify predictors of 25(OH)D3 concentrations stratified by sex.

RESULTS

Median 25(OH)D3 concentration was 64 nmol/L and none of the subjects had 25(OH)D3 concentrations < 25 nmol/L. In women, intact parathyroid hormone (iPTH) (β = -0.323), % total body fat (β = -0.208), time spent outdoors (β = 0.328), month of blood sampling (β = 0.229) and intake of vitamin D supplements (β = 0.172) were the predominant predictors of 25(OH)D3, whereas in men, iPTH (β = -0.254), smoking (β = -0.282), physical activity (β = 0.336) and monthly household net income (β = 0.302) predicted 25(OH)D3 concentrations. The final regression models accounted for 30% and 32% of the variance in 25(OH)D3 concentrations in women and men, respectively.

CONCLUSIONS

The findings indicate that 25(OH)D3 concentrations are influenced by body composition, month of blood sampling, economic factors, lifestyle, supplement intake and iPTH, but may not be associated with age, sex, dietary factors, kidney function and presence of selected chronic diseases in community-dwelling elderly. Furthermore, our results provide evidence for sex-specific determinants of the vitamin D status, which ought to be considered for preventive strategies.

BACKGROUND

Secondary hyperparathyroidism (SHPT) in patients on hemodialysis is strongly associated with cardio-vascular morbidity and mortality. Treatment of SHPT with cinacalcet decreases circulating parathyroid hormone (PTH) concentrations and lowers serum calcium and phosphorus concentrations. Therefore, we investigated the cardiovascular effects of cinacalcet in hemodialysis patients with SHPT.

METHODS

We studied 12 hemodialysis patients with SPHT [serum intact PTH (iPTH) >300 pg/ml]. The study consisted of three phases: an initial run-in period of 16 weeks, including a wash-out period of 4 weeks (pretreatment), a cinacalcet treatment period of 20 weeks (treatment), and 20-week follow-up after suspension of cinacalcet treatment (posttreatment). In this study, vitamin D sterols were not prescribed to all the study subjects for at least 1 year during the pretreatment period.

RESULTS

Cinacalcet significantly decreased serum iPTH (pretreatment vs. treatment; 628.2 ± 250.8 vs. 251.7 ± 237.4 pg/ml, p < 0.01), calcium, phosphorus, and calcium × phosphorus product (p < 0.01), all of which returned to baseline levels after treatment. There was no change in C-reactive protein during the study period. There was significantly improvement in brachial flow-mediated dilatation (p < 0.01) and enhanced cardio-ankle vascular index (p < 0.01) with cinacalcet treatment. Moreover, cinacalcet significantly improved diastolic function (E/e' ratio, p < 0.05) and the left ventricular mass index (p < 0.05). Cinacalcet also increased serum NO x (p < 0.05) and decreased serum isoprostane (p < 0.05) and soluble intercellular adhesion molecule-1 concentrations (p < 0.05). All of these biochemical parameters returned to their pretreatment concentrations after withdrawal of cinacalcet.

CONCLUSIONS

Cinacalcet hydrochloride without vitamin D might ameliorate endothelial dysfunction, diastolic dysfunction, and cardiac hypertrophy by decreasing oxidative stress and increasing the serum nitric oxide production in hemodialysis patients with SHPT.

BACKGROUND

Vascular calcifications (VCs) and renal osteodystrophy (ROD) are frequently seen together and represent the major causes of morbidity and mortality in hemodialysis (HD) patients. Some studies suggest a pathogenic link between them, but there is no consensus as yet regarding this issue. The main objective of our study was to establish whether there is any relation between VCs and ROD in our HD patients. We evaluated the prevalence of VCs and ROD and the relationship between VCs and some clinical and biochemical characteristics of HD patients.

METHODS

We examined radiological signs of VCs and ROD on hands and pelvis bone radiographs in 81 chronic HD patients, and we calculated a VC score on this basis.

RESULTS

We found a significant relation between radiological signs of ROD and those of VC (P = 0.019). The patients with ROD had a higher mean VC score (P = 0.02). By linear regression, the VC score correlated directly with serum calcium (Ca), phosphorus (P), intact parathyroid hormone (iPTH) and CaxP product and inversely with serum albumin. The logistic regression model revealed that ROD, male gender and treatment with calcium salts were predictive of VCs development. There were no associations between VCs and age, HD vintage, diabetes, dialysate Ca concentration, vitamin D treatment, spKt/V, URR and C-reactive protein (CRP) levels.

CONCLUSIONS

There seems to be a pathogenetic link between bone and artery diseases in chronic HD patients. Both VCs and ROD have a high prevalence. ROD, male gender and treatment with calcium salts are risk factors for VCs.