P. V. L. N. Srinivasa Rao

Antioxidant defense in overt and subclinical hypothyroidism.

Oxidative stress as a result of disequilibrium between free radical generation and antioxidant status has been implicated in several pathologies including thyroid diseases. Studies on antioxidant status in overt (OHT) and subclinical hypothyroidism (SHT) are controversial and limited. The aim of this study was to determine the effect of OHT and SHT on antioxidant status. Thirty-six patients with OHT, 36 patients with SHT, and 39 healthy euthyroid subjects as the control group were included in the study. Plasma levels of malondialdehyde (MDA), reduced glutathione (GSH) and total antioxidant capacity (TAC) as ferric reducing ability of plasma (FRAP), and erythrocyte antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx), SOD/GPx ratios, catalase (CAT), and glutathione reductase (GR) were analyzed in all groups. MDA and GPx values were elevated, while GSH, FRAP, SOD, and SOD/GPx ratio were decreased in both patient groups compared with controls. No change in activities of CAT and GR were observed in both the patient groups. Significant differences were observed between OHT and SHT groups with high MDA, GPX and low GSH, FRAP, SOD, and SOD/GPx ratio in OHT group. Thus, hypothyroid patients have a deficient antioxidant defense in the form of decreased activity of SOD, decreased levels of FRAP and GSH along with an increase in GPx activity. The severity of the disease appears to decide the degree of deficiency and our findings also point to this, in the form of decrease in SOD, FRAP, and GSH observed being more in OHT than in SHT patients. Hormonal changes and increased lipid peroxidation, which also vary with severity of disease, appear to contribute to the antioxidant deficiency.

Lipoprotein (A): Better assessor of coronary heart disease risk in south Indian population

In an attempt to search for risk factors which can explain the increasing prevalence of coronary heart disease (CHD) in Indian population, we conducted a case-control study to assess the association of Lipoprotein (a)(Lp(a)) with CHD. One hundred and fifty one consecutive patients with clinical and angiographic evidence of CHD and forty-nine healthy controls were drawn for the study. Triglycerides, very low density cholesterol (VLDL-C), total cholesterol (total-C)/high density cholesterol (HDL-C) ratio, low density cholesterol (LDL-C)/HDL cholesterol ratio and Lp(a) were found to be higher in patients than controls. In female sex and in those with family history of CHD, higher total and LDL cholesterol levels were observed to be associated with higher Lp(a) levels. Lp(a) levels were also found to be higher in triple vessel disease than other vessel disease patients. Significant difference in Lp(a) levels were observed between normal coronaries vs. single and triple vessel disease(P<0.05) and also between single vs. double and triple vessel disease (P<0.01).Lp(a) levels correlated positively with vessel severity(P<0.005). Lp(a) levels >25 mg/dl were associated with coronary heart disease (Odds ratio 1.98 P<0.05 95% CI 0.007–1.18). Our findings suggest a cut-off level of 25mg/dl for determination of risk of CHD. Studies from different areas involving larger sample size are needed to confirm the findings of the present study.

Interferences in clinical chemistry analysis

Analyses of body fluids in clinical chemistry laboratory are subject to a number of interferences that affect the analytical accuracy. The interferents arise from exogenous sources like drugs and additives as well as such endogenous sources like lipemia, hemolysis and icteria. Our studies demonstrate matrix interference in the form of analytical blas between serum and aqueous matrix calibrators. The clinical chemist should constantly be aware of this factor. Correction of interferences is recommended as an integral part of the quality assurance program.

Utility of saliva as a sample to assess renal function and estimated glomerular filtration rate.

Diagnosis of renal diseases by assessing renal parameters in saliva. Biochemical investigations using serum form important component of monitoring patients with renal disease. Utility of saliva, in diagnosis and monitoring of patients with renal disease and for calculation of estimated glomerular filtration rate (eGFR), was studied. Sixty patients with renal disease and sixty ageand sex-matched healthy controls were studied. Urea, creatinine, sodium, potassium, uric acid, calcium, and phosphorus were measured in both serum and saliva. eGFR was calculated using salivary creatinine. Data were expressed as mean ± standard deviation. Comparison and correlation between groups were assessed by Students t-test and Pearson correlation, respectively. Bland-Altman plot, mountain plot, and intra-class correlation coefficient were used to test agreement. A P <0.05 was considered statistically significant. Statistical analysis was done using Microsoft excel spreadsheets, Medcalc Version 10.0, and SPSS version 11.5. Salivary levels of urea, creatinine, uric acid, sodium, potassium, and phosphorus were higher in patients compared to controls. Potassium and phosphorus levels were higher (P = 0.001) and creatinine, sodium, calcium, and uric acid levels were lower (P = 0.001) in saliva compared to serum in both patients and controls. Positive correlation was observed between serum and salivary urea and creatinine (P < 0.0001). eGFR values calculated from salivary creatinine showed good agreement with those calculated form serum creatinine. Salivary urea (>6 mmol/L) and creatinine (>14.6 μmol/L) and eGFR calculated from salivary creatinine can be used to identify patients with renal disease.

Serum ischaemic-modified albumin levels might not be a marker of oxidative stress in patients with hypothyroidism.

Of great interest, we read an article by Ersoy et al. [1] who concluded that the ischaemia-modified albumin (IMA) level did not differ among overt and subclinical hypothyroid patients in comparison to controls and also by age, sex and the presence of metabolic syndrome (MS). They went on to say that the thyroid status per se has no influence on IMA result and oxygen radical production does not occur in hypothyroid patients. However, based on our experience [2] and others [3–8], few issues come to mind. At first, hypercholesterolaemia, the characteristic feature in hypothyroidism has been reported to be associated with an increase in inflammation, oxidative stress and also reduces the capacity of albumin to bind cobalt resulting in increased IMA level [3]. In their study, 53.8 % of overt hypothyroid patients were also reported to have MS diagnosed according to Adult Treatment Panel III/National Cholesterol Education Program (ATP III/NCEP) criteria. Despite showing no change in the levels of HDL, LDL and Triglycerides in overt and subclinical hypothyroid groups, there is no information on total-cholesterol level that would have been adequately addressed. This appears to be important as hyperlipidemia/hypercholesterolaemia alters albumin cobalt binding and IMA result. Moreover, the study of Ersoy et al. [1] differ to that of Ma and colleagues [6], who reported significant alterations in lipid variables and IMA level in hypothyroid patients versus controls. Second, hypothyroidism is known to affect albumin concentrations and because of dependence of IMA values on albumin level, it would be important to report albumin levels and IMA values corrected for albumin interference [4]. This issue is important in principle: estimation of IMA involves cobalt binding to albumin and measuring the colour developed by un-bound cobalt through albumin cobalt binding assay. Third, one would not expect to see a difference between groups that greatly differ in respects of sample-size. Among a total of 85 study subjects, there were only less number of males (11), smokers (8) and subjects with MS (31). This limitation, though stated, might have influenced the results and hence the conclusions made. Given that the previous report [5] demonstrated increased IMA values in MS, it would have been interesting to study only hypothyroidism as one group and only MS as the other. Though IMA level in hypothyroidism is lower than that found in acute conditions like diabetic ketoacidosis [7], a significant increase within normal range has been recently reported in hypothyroidism [6]. There is also evidence of increased IMA in MS [5]. Therefore, although the occurrence of MS in hypothyroidism is chronically secondary, presence of MS component in hypothyroidism may possibly contribute to further increase in oxidative stress. However, in the study by Ersoy et al. [1], it has been found that the presence of MS does not influence IMA levels in hypothyroidism. This is despite of diagnosing MS using ATP III/NCEP criteria in both studies [5, 6]. In addition, evidence of increased protein carbonylation suggests the role of hypothyroid disease on protein oxidation [2]. Despite the aforementioned information, it is of much importance that Ersoy et al. [1] demonstrated IMA levels in different degrees of hypothyroidism; overt and subclinical type. V. S. Reddy (&) R. Garg Department of Biochemistry, B.P.S. Govt. Medical College for Women, Sonepat 131305, Haryana, India e-mail: lifeschemistry@live.com

Role of gut-derived uremic toxins on oxidative stress and inflammation in patients with chronic kidney disease

Several cardiovascular disease (CVD) risk factors have been identified among patients with chronic kidney disease (CKD). Gut-derived uremic toxins (GDUT) are important modifiable contributors in this respect. There are very few Indian studies on GDUT changes in CKD. One hundred and twenty patients older than 18 years diagnosed with CKD were enrolled along with forty healthy subjects. The patients were classified into three groups of forty patients based on stage of CKD. Indoxyl sulfate (IS), para cresyl sulfate (p-CS), indole acetic acid (IAA), and phenol were estimated along with the assessment of oxidative stress (OS), inflammatory state, and bone mineral disturbance. All the GDUT increased across the three groups of CKD. All patients had higher levels of malondialdehyde (MDA), ferric reducing ability of plasma (FRAP), high-sensitivity C-reactive protein (hsCRP), and interleukin-6 (IL-6) as compared to controls. IS and IAA showed positive association with MDA/FRAP corrected for uric acid, whereas IS and p-CS showed positive association with IL-6. IS, IAA, and phenol showed a positive association with calcium × phosphorus product. GDUT increase OS and inflammatory state in CKD and may contribute to CVD risk.

Analytical bias due to calibrator matrix effects

Fresh serum specimens from 50 patients were analysed for all routine analytes using calibration with serum matrix calibrator as well as aqueous matrix calibrators. Despite good correlation, there is statistically significant bias between serum and aqueous matrix calibrations for most of the analytes. In addition, the bias in cases of glucose, cholesterol and triglycerides is more than the medically allowable error. A proportional systematic error was found pointing to a calibration disparity between the two types of calibrators. These findings suggest an analytical bias between serum and aqueous matrix calibrations that could result in a lack of commutability among various laboratories.

Lipid abnormalities, lipoprotein (a) and apoprotein pattern in non-dialyzed patients with chronic kidney disease

The present study was carried out to explore the altered lipid, lipoprotein and apoprotein abnormalities along with lipoprotein (a) in chronic kidney disease patients with stage I to V which were further divided into group 1 (stage I and II), group 2 (stage III and IV) and group 3 (stage V). 50 chronic kidney disease patients with stage I to V and 20 healthy normal subjects as controls were recruited for this study. Among the various parameters tested triglyceride levels were high in group 1 and 2, whereas VLDL cholesterol, Lp (a) and apo B levels were significantly high in all the groups when compared to controls (P<0.05). However, LDL cholesterol level was significantly low in group 3 only as compared to control group (P<0.05). Apoprotein AI values also showed significant decrease in all groups as compared to controls (P<0.05). Though total cholesterol levels in group 1 and LDL levels in group 1 and 2 were higher than controls, but the values attained not statistically significant (P>0.05). In conclusion high levels of VLDL cholesterol, Lp (a), apo B and low levels of apoprotein AI as reported in this study are the major lipid disorders in the development of cardiovascular complications at all the stages in these patients.

THYROID HORMONE PROFILE IN PERITRANSPLANT PERIOD IN LIVE DONOR KIDNEY TRANSPLANTATION

Chronic renal failure, characterised by two factors acting in opposite directions with respect to the serum thyroid homone levels was chosen for the study. Healthy controls, donors undergoing nephrectomy and renal transplant recipients were studied. In transplant recipients, presurgical levels of total thyroxine(TT4), free triiodothyronine(FT3) and free thyroxine(FT4) were lower than controls, and immediately after the release of arterial clamps, there was an upsurge of total triiodothyronine (TT3), TT4, FT3 and FT4 due to administered and/or endogeneously secreted catecholamines. The levels of the 7th day were comparable to the presurgical levels. The changes observed in donors and recipients were similar indicating that the hormonal changes observed are mostly due to surgical stress. Recovery in the hormonal status did not start in the first week of posttransplant period.

Carbamylated hemoglobin can differentiate acute kidney injury from chronic kidney disease

Carbamylated hemoglobin (CarHb) was found to have a potential role in the differentiation of patients with acute kidney injury (AKI) from chronic kidney disease (CKD). This study was aimed at the evaluation of the diagnostic performance and usefulness of CarHb in the differentiation of AKI from CKD. Forty patients with renal disease and twenty age- and sex-matched healthy controls were included in the study. Urea, creatinine, Hb, and CarHb were measured in all the subjects. Patients with AKI and CKD were found to have significantly increased levels of CarHb when compared to controls (P < 0.05 for both groups). Patients with CKD had significantly increased levels of CarHb when compared to patients with AKI (P < 0.05). CarHb showed significant positive correlation with urea in patients with renal disease (r = 0.776, P < 0.0001). Significant area under curve (AUC = 0.840, P < 0.0001) was obtained for CarHb and a cut-off value of 98.33 μg VH/g Hb resulted with the best combination of 85% sensitivity and 75% specificity. CarHb may provide clinical utility since patients with AKI and CKD have similar clinical presentation usually. A cut-off value of 98.33 μg VH/g Hb has been found to be useful to differentiate AKI from CKD.