BACKGROUND

Ischemia-modified albumin has been proposed as a useful rule-out marker for the diagnosis of acute coronary syndrome in the emergency department.

OBJECTIVE

To perform a review of ischemia-modified albumin use in the clinical practice.

METHODS

We performed a comprehensive literature search by using electronic bibliographic databases.

CONCLUSIONS

Although the main limitation of ischemia-modified albumin at present is its low specificity, it may be a useful test to rule out acute coronary syndrome from low to moderate pre-test probability conditions with negative cardiac troponins and a negative ECG.

BACKGROUND

A novel ischemia marker named ischemia modified albumin was previously considered as an early marker of myocardial ischemia, however due to recent reports, its contribution was demonstrated in different pathologies such as oxidative stress, diabetes, stroke and cancer. We aimed to investigate the relation between oxidative stress and thyroid dysfunctions determining IMA levels since IMA is closely related with increased oxidative stress.

METHODS

A total of 88 individuals were participated in this study: 34 cases in hypothyroid, 27 cases in hyperthyroid and 27 cases in euthyroid group. Ischemia-modified albumin levels were measured by albumin cobalt binding test and thyroid hormone levels were determined with electrochemiluminescent method.

RESULTS

Ischemia modified albumin levels were significantly decreased in hypothyroid group compared to hyperthyroid and euthyroid groups (p < 0.001). In hyperthyroid individuals ischemia modified albumin levels were higher compared to euthyroid ones (p < 0.001). Ischemia modified albumin was negatively correlated with TSH levels (r = -0.473, p < 0.001), and positively correlated with FT4 and FT3 levels (r = 0.496, p < 0.001 and r = 0.275, p = 0.010, respectively).

CONCLUSIONS

We suggest that albumin adjusted IMA levels are significantly lower in hypothyroid group than hyperthyroid and euthyroid groups.

The aim of this prospective case-control study was to determine the change in serum maternal ischemia-modified albumin (IMA) during normal pregnancies. A total of 117 pregnant (first trimester (n=24), second trimester (n=34), and third trimester (n=35)) and non-pregnant healthy women (n=23) were included. Maternal serum IMA, Malondialdehyde (MDA), and albumin levels were measured. Compared with non-pregnant women, the cross-sectional mean IMA levels in pregnant women were significantly increased, while the mean serum MDA and albumin levels were significantly decreased throughout pregnancy. Furthermore, a significant negative correlation between serum IMA and albumin levels (r=-0.354, p<0.001) was found, and there was a weak positive correlation between serum albumin and MDA levels (r=0.334, p<0.001). Serum IMA, which has recently been developed as a clinical marker of ongoing myocardial ischemia, appears to be elevated in normal pregnancy. This may be due to the physiologic oxidative stress state of pregnancy.

OBJECTIVE

To investigate the effect of obstructive sleep apnea and continuous positive airway pressure treatment on serum butyrylcholinesterase activity and ischemia-modified albumin levels.

METHODS

Thirty-two patients with obstructive sleep apnea and 30 age- and sex-matched controls were enrolled and underwent a diagnostic polysomnogram. The serum butyrylcholinesterase activity, ischemia-modified albumin levels, metabolic parameters, and polysomnography scores were detected and evaluated. Nine patients were studied before and after treatment with continuous positive airway pressure.

RESULTS

The serum ischemia-modified albumin levels were significantly higher and the butyrylcholinesterase activity was significantly lower in patients with obstructive sleep apnea than in the controls (p<0.001). The continuous positive airway pressure treatment decreased the modified albumin levels and elevated the buthrylcholinesterase activity (p=0.019 and p=0.023, respectively). The modified albumin levels were positively correlated with the apnea-hypopnea index (r=0.462, p=0.008) at baseline. Elevated ischemia-modified albumin levels can be more accurate than butyrylcholinesterase activity at reflecting the presence of obstructive sleep apnea. Receiver operating characteristic curves revealed a significant difference between the areas under the curve 0.916 for ischemia-modified albumin and 0.777 for butyrylcholinesterase (z=2.154, p=0.031).

CONCLUSIONS

The elevated ischemia-modified albumin level was significantly associated with obstructive sleep apnea and was more sensitive than butyrylcholinesterase activity in reflecting obstructive sleep apnea. The continuous positive airway pressure treatment helped to ameliorate the imbalance.

Ischemia modified albumin (IMA) is a new biological marker for early identification of chest pain and ruling out myocardial infarction among patients with acute syndromes submitting to emergency department. Recently IMA has been investigated in the light of other cardiac markers (cTnT, CK-MBmas, NT-proBNP) in various states of ischemia (acute coronary syndromes, after percutaneous coronary intervention, in coronary vasospasm). Ischemia modified albumin levels were elevated in these states what suggests myocardial ischemia. However decrease in IMA concentration after exercise-induced skeletal muscle ischemia still remains unclear. Increased IMA concentration in patients with acute ischemic stroke and exposed to trauma limits its ability for detection myocardial ischemia. Specificity of IMA measurement is limited also in patients with peripheral vascular disease, systemic sclerosis, diabetes, end stage renal disease, pulmonary embolism and other pathological states with accompanying oxidative stress.

OBJECTIVE

To investigate the serum ischemia-modified albumin levels with use of an experimental testicular torsion (TT) model.

METHODS

Randomized, controlled experimental study.

METHODS

University hospital.

METHODS

Thirty mature male Wistar rats.

METHODS

Rats were divided into five groups: a sham operation group, 2- and 4-hour control (groups I and III, respectively), and 2- and 4-hour torsion groups (groups II and IV, respectively). Ischemia-modified albumin, tissue and blood malondialdehyde (MDA), tissue and blood myeloperoxidase (MPO) activity levels, and histopathologic damage scores then were compared.

METHODS

Ischemia-modified albumin, tissue and blood MDA, tissue and blood MPO activity levels, and histopathologic damage scores.

RESULTS

There was a significantly higher level of histopathologic damage in the 4-hour torsion group, and the serum ischemia-modified albumin levels in this group were significantly higher than those of the other groups. There was no difference between the groups in terms of blood and tissue MDA and MPO levels. There was no significant correlation between ischemia-modified albumin levels and blood and tissue MDA and MPO levels. The only significant correlation between histopathologic score and biochemical markers was that with blood and tissue MPO.

CONCLUSIONS

The results from this pioneering study determined a high level of ischemia-modified albumin in TT, indicating a potential value for TT diagnosis. The value of ischemia-modified albumin levels in TT should be investigated also with respect to prognosis.

BACKGROUND

An early identification of the patients with the Acute Coronary Syndrome (ACS) is of prime importance, due to the associated very high mortality. Only about 22% of the patients who present at the emergency cardiology care centres with chest pain, have coronary disease. Ischaemia modified albumin has already been licensed by the US Food and Drug Administration for the diagnosis of suspected myocardial ischaemia.

OBJECTIVE

The goal of the present study was to assess the diagnostic value of serum ischaemia modified albumin and to compare it with sensitive cardiac troponin I in patients with the acute coronary syndromes like unstable angina and acute myocardial infarction.

METHODS

A diagnostic case control study was conducted on 102 patients who presented to the Emergency Department within 6 hrs of having acute chest pain and on 110 healthy age and sex matched volunteers who formed the control group. The serum Ischaemia Modified Albumin level was estimated by the albumin cobalt binding test by using a digital spectrophotometer, while Troponin I was measured by doing an immunofluroscence assay. A receiver operating characteristic curve was established for ischaemia modified albumin, to determine the cut-off point. The sensitivity and the specificity of ischaemia modified albumin and troponin I for the detection of acute coronary syndromes, were analyzed. The results of ischaemia modified albumin and troponin I alone and in combination, were correlated.

RESULTS

The ischaemia modified albumin (p<0.05) and the troponin I (p<0.001) concentrations were significantly higher in acute myocardial infarction and in unstable angina than in the healthy controls. The sensitivity and the specificity of ischaemia modified albumin for the detection of acute coronary syndromes was 88% and 93% as compared to 87% and 75% respectively for troponin I. The combined use of ischaemia modified albumin and troponin I significantly enhanced the sensitivity to 96%. The area which was under the Receiver Operating Characteristic (ROC) curve of ischaemia modified albumin in acute coronary syndromes was 0.90.

CONCLUSIONS

Ischaemia modified albumin is a useful biochemical marker for the early diagnosis of acute coronary syndrome. The combined use of ischaemia modified albumin and cardiac troponin I enhances the sensitivity and specificity. Hence, a combination of ischaemia modified albumin and cardiac troponin I can be used as a more precise diagnostic marker for Acute Coronary Syndrome.

OBJECTIVE

The objective of this study is to investigate the ischemia-modified albumin (IMA) level, and the IMA/albumin ratio (IMAR) in healthy pregnant women, and pregnant women with intrahepatic cholestasis of pregnancy (ICP).

METHODS

This cross-sectional study included 53 women with ICP and 52 healthy pregnant women. Their serum IMA and albumin levels were analyzed, and the women were followed up to delivery.

RESULTS

No significant intergroup differences were identified in maternal age, body mass index, and gestational age at the time that the blood samples were taken. The gestational age at delivery and the serum albumin level was significantly lower (p = .002 and p < .0001, respectively) in the ICP group than in the healthy pregnant women. Although no differences in IMA levels were shown between the groups, IMA/albumin levels were higher in the ICP group than in the healthy pregnant women (p = .004).

CONCLUSIONS

Serum IMA levels did not differ between pregnant women with ICP and healthy pregnant women, while the IMAR was significantly higher in the ICP group versus the healthy pregnant women.

OBJECTIVE

There is concern that ischemia-modified albumin (IMA) levels measured by albumin cobalt binding (ACB) assay reflect mainly albumin concentrations rather than myocardial ischemia.

METHODS

Serum matrix and proteins were separated from a serum pool by a membrane filter. Two series of pools with albumin concentrations of 10, 20, 30, 40, 50, and 60 g/L were prepared either with human albumin or serum protein fraction. IMA values of these pools were measured in quintiplicate.

RESULTS

There was a strong negative correlation between IMA and albumin levels in both pools. IMA change corresponding to each 10 g/L difference in albumin concentration was 37% and 48% in these pools.

CONCLUSIONS

ACB assay reflects albumin concentrations rather than IMA. Primary predictor of IMA in serum matrix is albumin concentration.

Perinatal asphyxia is a significant cause of perinatal morbidity and mortality worldwide. It is estimated that around 23% of all newborn deaths are caused by birth asphyxia. Each year, between four and nine million newborns develop birth asphyxia worldwide, according to the World Health Organization (WHO). Therefore, despite major advances in monitoring and knowledge of fetal and neonatal physiology and development, perinatal asphyxia remains a serious condition that causes significant mortality and long-term morbidity. However, to date no single marker of perinatal asphyxia has shown good predictive efficacy in prediction and early diagnosis of perinatal asphyxia. On the other hand, ischemia-modified albumin (IMA) is a new biomarker in identification of myocardial ischemia of myocardial necrosis. IMA may also increase in the ischemia of liver, brain, kidney and bowel. Ischemia of these organs may also seen in perinatal asphyxia as well. Reactive oxygen species, produced during ischaemia/reperfusion which is essential steps of perinatal asphyxia, may generate the highly reactive hydroxyl radicals. These hydroxyl radicals modify the albumin and transforms it into IMA. Therefore, IMA might be useful for the prediction and diagnosis of perinatal asphyxia. Further studies are urgently needed to determine the role of IMA in the prediction of perinatal asphyxia.

OBJECTIVE

To establish the value of ischemia-modified albumin levels in the determination of the long-term results of testicular torsion/detorsion-associated ischemia-reperfusion injury.

METHODS

Eighteen mature male Wistar rats were divided randomly into 3 groups (n = 6 for each group): control, acute torsion/detorsion (T/D) group, and long-term T/D. In the control group, scrotal incision only was performed; in the acute T/D group, after 4 hours of torsion, detorsion was performed and maintained for 2 hours. Blood samples and testicular tissue samples were taken after 2 hours of detorsion. The same T/D procedures were performed in the long-term T/D group. The long-term T/D groups were kept alive for 2 months, and samples were taken at 2 months post procedure. Serum ischemia-modified albumin, serum and tissue malondialdehyde levels, and histopathological damage scores were measured.

RESULTS

Serum ischemia-modified albumin levels were significantly higher compared with the control group, in the acute-term T/D (P = .004). This elevation remained pronounced in the long term compared with the control group and acute period (P = .008 and P = .017, respectively). There was a significant negative correlation between serum ischemia-modified albumin levels and histopathological injury score in both the torsioned and contralateral testes (r = -.929, P < .0001 and r = -.560, P = .02, respectively).

CONCLUSIONS

Ischemia-modified albumin is a valuable parameter in terms of reflecting testis injury in testicular torsion in both the acute period and the long term. It therefore has the potential to be used as data with predictive value regarding patients' fertility capacities.

BACKGROUND

Behçet's disease (BD) is a chronic inflammatory disorder with endothelial dysfunction. Ischemia-modified albumin (IMA) is a marker used in the detection of diseases associated with oxidative stress, vascular endothelial cell dysfunction and ischemia. Mean platelet volume (MPV) signifies the platelet function and activity.

OBJECTIVE

To show whether MPV and IMA are useful in revealing the oxidative stress and the risk of thrombosis in patients with BD.

METHODS

Twenty-six patients with BD and 28 healthy volunteers as a control group over 18 years of age were included in the study. Serum IMA and MPV levels were analyzed in both groups.

RESULTS

The mean MPV values were identified as 0.86 ±0.15 and 0.82 ±0.08 (in the BD and control groups, respectively; p = 0.188) and the mean IMA values were 9.39 ±0.73 and 9.17 ±1.09 (in the BD and control groups, respectively; p = 0.275). There were no statistically significant differences between the groups. The IMA values of BD patients who were in the active phase were significant as compared to inactive BD patients and control groups (p = 0.041). The IMA and MPV values of the thrombotic patients, non-thrombotic patients and control groups were not significant.

CONCLUSIONS

Ischemia-modified albumin may be a helpful marker of possible complications during an active period of BD.

BACKGROUND

Ischemia-modified albumin (IMA), a novel ischemia marker, and mean platelet volume (MPV), a determinant of platelet activation, have been reported as elevated markers in cardiovascular risk factors such as atherosclerosis, metabolic syndrome, diabetes mellitus (DM), hypertension, and dyslipidemia. As psoriasis is a chronic inflammatory disease having comorbidities, IMA and MPV can help determine the risk factors for psoriasis.

OBJECTIVE

To investigate the correlation between the psoriasis area severity index (PASI), IMA and MPV levels in patients with psoriasis.

METHODS

This cross-sectional, case-control study was performed between January 2014 and December 2014 at the University hospital in Çanakkale, Turkey. Forty-five patients with psoriasis and 44 healthy volunteers over 18 years of age were included in the study. In the psoriasis patient group, clinical features and PASI scores were recorded. Serum IMA and MPV concentrations were evaluated in both groups.

RESULTS

The mean IMA values were 0.85 ±0.15 and 0.79 ±0.09 (in the psoriasis patients and control groups, respectively), and there was a statistically significant difference (p = 0.048). Ischemia-modified albumin levels were not correlated with PASI scores (r = 0.024; p = 0.889) but were correlated with disease duration (r = 0.323; p = 0.048). There was no statistically significant difference between the MPV values of the two groups (8.98 ±1.14 and 9.19 ±1.28 in the psoriasis patients and control groups, respectively) (p = 0.435).

CONCLUSIONS

Ischemia-modified albumin may be used as a marker for detecting oxidative stress in patients with psoriasis, especially those with a long disease duration.

OBJECTIVE

To evaluate the predictive effect of IMA in incarcerated hernias.

METHODS

Three groups (n = 7) of rats were operated. Group I aimed to mimic incarceration, group II aimed the strangulation, and group III was the sham group. IMA and LDH measurements were made.

RESULTS

IMA levels were significantly higher in strangulation mimicking group and IMA levels were normal at postoperative 6th hour in incarceration mimicking group. LDH levels were significantly higher in both incarceration and strangulation mimicking groups.

CONCLUSIONS

IMA seems to be an effective marker in incarcerated hernias to predict necrosis. But we need further studies to generalise this hypothesis.

BACKGROUND

The central nervous system (CNS) is extremely vulnerable to ischemic injury. The details underlying this susceptibility are not completely understood. Since the CNS is surrounded by cerebrospinal fluid (CSF) that contains a low concentration of plasma protein, we examined the effect of changing the CSF in the evolution of CNS injury during ischemic insult.

METHODS

Lumbar spinal cord ischemia was induced in rabbits by cross-clamping the descending abdominal aorta for 1 h, 2 h or 3 h followed by 7 d of reperfusion. Prior to ischemia, rabbits were subjected to the following procedures; 1) CSF depletion, 2) CSF replenishment at 0 mmHg intracranial pressure (ICP), and 3) replacement of CSF with 8% albumin- or 1% gelatin-modified artificial CSF, respectively. Motor function of the hind limbs and histopathological changes of the spinal cord were scored. Post-ischemic microcirculation of the spinal cord was visualized by fluorescein isothiocyanate (FITC) albumin.

RESULTS

The severity of histopathological damage paralleled the neurological deficit scores. Paraplegia and associated histopathological changes were accompanied by a clear post-ischemic deficit in blood perfusion. Spinal cord ischemia for 1 h resulted in permanent paraplegia in the control group. Depletion of the CSF significantly prevented paraplegia. CSF replenishment with the ICP reduced to 0 mmHg, did not prevent paraplegia. Replacement of CSF with albumin- or gelatin-modified artificial CSF prevented paraplegia in rabbits even when the ICP was maintained at 10-15 mmHg.

CONCLUSIONS

We conclude that the presence of normal CSF may contribute to the vulnerability of the spinal cord to ischemic injury. Depletion of the CSF or replacement of the CSF with an albumin- or gelatin-modified artificial CSF can be neuroprotective.

OBJECTIVE

There is limited and contradictory information regarding the role of serum ischemia-modified albumin (IMA) in obstructive sleep apnea (OSA). In this study we examine the effects of OSA and obesity on IMA and interleukin-6 (IL-6), and detect whether IMA and IL-6 may be potential biomarkers in OSA.

METHODS

Fifty-one males who underwent all night polysomnography test were included into the study. Body-mass index (BMI) and apnea-hypopnea index (AHI) of all patients were determined. Serum IMA and IL-6 levels, erythrocyte sedimentation rate (ESR), complete blood count, routine blood biochemistry and thyroid function tests were performed.

RESULTS

Mean IMA [0.36 (± 0.04) U/ml, 0.89 (± 0.15) U/ml], mean IL-6 [1.01 (± 0.19) pg/ml, 2.02 (± 1.19) pg/ml] and mean ESR [4.14 (± 2.5) mm/h, 14.35 (± 13.7) mm/h] levels showed significant difference between non-OSA and OSA groups (P = 0.005, P < 0.001, P < 0.001, respectively). Sensitivity of IMA in distinction of non-OSA/OSA was equal to IL-6 and higher than ESR. IMA was also a stronger predictive factor than IL-6 and ESR in the evaluation of OSA groups (severe/mild/moderate OSA and non-OSA). IMA was the sole distinctive biomarker in assessment of obese and non-obese cases. IMA correlated with IL-6, AHI and ESR.

CONCLUSIONS

Serum IMA may be a valuable oxidative stress indicator for OSA and could act as a better biomarker than IL-6 for reflecting the presence and the severity of OSA.

OBJECTIVE

The aim of the article is to evaluate ischemia-modified albumin (IMA) levels in infants with transient tachypnea of the newborn (TTN) and to find out its relation to the disease severity. Patients and

METHODS

Infants with>> 37 weeks of gestation, without any respiratory and cardiac symptoms and without any maternal health problems, and diagnosed as TTN were allocated as the study group. Patients with obvious retractions, grunting, hypercarbia (Pco 2>> 60 mm Hg) or hypoxia (oxygen saturation < 88% with Fio 2 of 0.60) were managed with nasal continuous positive airway pressure (CPAP). During the postnatal 0 to 24 hours, blood samples were collected in 2 mL for IMA.

RESULTS

A total of 47 patients were diagnosed TTN, and allocated as the study group. Of the 47 patients, 43 patients without respiratory symptoms were enrolled as the control group. IMA levels in TTN were found to be significantly higher (p < 0.05). In addition, IMA levels were significantly increased in the nasal CPAP group versus supplemental oxygen therapy groups (p < 0.05). IMA levels were determined to be significantly higher in the>> 3 days of oxygen therapy group (p < 0.05). IMA levels with a cutoff point of 0.87 ABSU, sensitivity of 81.1% and specificity of 69.8% predicted TTN (area under the curve [AUC] = 0.85; p < 0.05). IMA levels with>> 0.98 ABSU, 78% sensitivity, and 86% specificity indicated the prediction of CPAP requirement (AUC = 0.86; p < 0.05).

CONCLUSIONS

IMA levels were significantly higher in infants with diagnosed TTN. Therefore, IMA may be used as a new marker for predicting TTN and disease severity.

This study investigated the value of Thiol/Disulfide homeostasis and ischemia-modified albumin (IMA) levels in discriminating diabetic cases with different stages of retinopathy and without retinopathy. In total, 122 patients with type 2 diabetes mellitus (DM) were enrolled in this prospective cross-sectional study. These patients were separated into three subgroups: Group 1 included 42 patients with DM and no diabetic retinopathy (DR), Group 2 included 40 patients with DM having non-proliferative DR and the Group 3 had 40 patients with DM having proliferative DR. The native thiol, total thiol, and disulfide levels and disulfide-native thiol, disulfide-total thiol, and native thiol-total thiol ratios as well as the IMA levels were analyzed and compared among the groups. There were no statistically significant differences regarding the ages and genders of the patients between the groups. The native thiol level, the total thiol level and the native thiol-total thiol ratio showed a statistically significantly reduction, while the disulfide level, the disulfide-native thiol ratio, and the disulfide-total thiol ratio showed a statistically significantly elevation in the Group 3 compared with the Group 1 and Group 2. Additionally, the mean IMA levels were statistically significantly higher in Group 3 when compared to Group 1 and Group 2 (p = .003 and p = .014, respectively). In conclusion, both Thiol/Disulfide homeostasis parameters and IMA levels increase with the progression of DR. Thiol/Disuldife homeostasis balance and IMA levels may be used a biomarker to monitor the tissue ischemia in DM and to discriminate the different stages of DR, in the future.

OBJECTIVE

To explore the changes of the concentration of serum ischemia modified albumin (IMA) and high sensitivity C-reactive protein (hs-CRP) in type 2 diabetic patients with retinopathy (DR).

METHODS

The concentration of serum IMA and hs-CRP in DR patients were determined by ELISA and rate nephelometry and compared with those in 83 no-DR (NDR) patients and 72 controls. The concentration of serum IMA and hs-CRP in 40 proliferative diabetic retinopathy (PDR) patients were compared with those in 39 no-PDR (NPDR) patients. Data was evaluated using analysis of PPMS version 1.5.Results are expressed as means + or - standard deviation of the mean. Statistical comparisons were performed by student's t-test or one-way analysis of variance followed by Dunnett's multiple comparison test and the means compared each other using q test.

RESULTS

The serum IMA and hs-CRP concentration in DR patients were (46.51 + or - 13.29) microg/L, (4.27 + or - 2.24) mg/L. The serum IMA and hs-CRP concentration in NDR patients were (25.47 + or - 9.33) microg/L, (2.96 + or - 1.84) mg/L. The serum IMA and hs-CRP concentration in controls were (15.36 + or - 4.27) microg/L, (1.86 + or - 0.97) mg/L. The serum IMA and hs-CRP concentration in PDR patients were (54.72 + or - 15.61) microg/L, (6.34 + or - 3.53) mg/L. The serum IMA and hs-CRP concentration in NPDR patients were (38.35 + or - 11.27) microg/L, (3.28 + or - 1.77) mg/L. The serum IMA and hs-CRP concentration were significantly higher in DR patients than those in controls and NDR patients, the serum IMA and hs-CRP concentration in NDR patients were significantly higher than those in controls (F = 197.124, 34.561;q = 5.41-27.34; P < 0.01); the serum IMA and hs-CRP concentration were significantly higher in PDR patients than those in NPDR patients (t = 5.46, 4.89; P < 0.01); there was significant positive correlation between serum IMA concentration and hs-CRP concentration in DR patients (r = 0.617, P < 0.01).

CONCLUSIONS

The serum IMA and hs-CRP concentration were significantly high in DR patients, and were positively associated with the seriousness of DR, which may contribute to the development of DR.

Ten patients (9 males and 1 female: mean age: 64.8 +/- 7 yr) were studied. They were all stabilized coronary heart disease patients free of cardiac failure who where to undergo normovolaemic haemodilution as medical treatment of lower limb arteritis. Ventricular function was assessed by a radioisotope method: myocardial perfusion (thallium-201 and dipyridamole scintillation scan) and left ventricular contraction by technetium-99m angiography. Blood volume was measured by iodine-131 marked albumin. The following parameters were also measured: plasma viscosity, blood viscosity at seven different speeds, red blood cell aggregation index and filtration index. These were all measured before and 24 h after normovolaemic haemodilution which was carried out with à 5% albumin solution. This haemodilution was well tolerated: 1,062 +/- 335 ml of blood were sampled, the same volume of albumin being transfused, thus reducing the mean haematocrit from 0.42 +/- 0.05 to 0.32 +/- 0.02 (p less than 0.01). Normovolaemia was respected. Blood viscosity was reduced, especially at low speeds and the red blood cell aggregation index was also reduced. Ventricular contraction did not vary. Moreover, the basal myocardial state as assessed by the thallium scintillation count was not modified by the haemodilution, even being improved in three cases. The dipyridamole perfusion (the equivalent of an effort test) gave no changes in seven patients, resolved the ischaemic signs in two patients and slightly increased ischaemia in one case.