Effect of thyroid function status in hemodialysis patients on erythropoietin resistance and interdialytic weight gain.

Thyroid function abnormalities are common in hemodialysis (HD) patients. Here, we investigated their frequency and impact on intradialytic hemodynamics and erythropoietin resistance index (ERI). Demographic and laboratory data including thyroid-stimulating hormone (TSH), interdialytic weight gain, and intradialytic blood pressure (BP) changes were measured, and ERI was calculated. The prevalence and causes of abnormities in TSH and free thyroxine (FT4) and their effects on ERI and intradialytic hemodynamics were then assessed. One hundred and thirty patients (mean age, 57.1 ± 19.2 years; 66.4% diabetic, 86.7% hypertensive) were enrolled. Among them, 16.7% had hypothyroidism, 2.3% had hyperthyroidism, and 10.9% had subclinical hypothyroidism. TSH level was significantly associated with higher BP (P <0.05), lower albumin (3.6 ± 4.4 and 2.6 ± 1.8, respectively; P = 0.05), lower dialysis hours (3.9 ± 5.3 and 2.6 ± 1.8, respectively), and lower ERI (3.7 ± 4.4 and 2.4 ± 1.9, respectively; P = 0.05). FT4 was significantly associated with higher interdialytic weight gain (13.4 ± 4.3 and 11.8 ± 2.2 pmol/L, respectively; P = 0.009) and higher pre-HD diastolic BP (13.2 ± 4.0 and 12.0 ± 2.9 pmol/L, respectively; P = 0.05). A negative correlation was seen between TSH level and urea reduction ratio (r = 0.29, P = 0.002), serum albumin (r = 0.304, P = 0.001), hemoglobin level (r = 0.26, P = 0.005), and ERI (r = 0.2, P = 0.002). A higher TSH level was associated with hypertension, lower albumin level, fewer dialysis hours, and increased resistance to erythropoietin. TSH level was negatively correlated with dialytic adequacy, serum albumin level, hemoglobin level, and ERI.

What is the most appropriate formula to use in estimating glomerular filtration rate in adult Arabs without kidney disease?

BACKGROUND: In clinical practice, the glomerular filtration rate (GFR) is often estimated by the Modification of Diet in Renal Disease (MDRD) or Cockcroft-Gault (CG) formulae. No data are available, however, on the performance of these formulae in Arab individuals. METHODS: Plasma creatinine samples were obtained from 90 consecutive normal Arab kidney donors for the estimation of GFR (eGFR) using the simplified MDRD and CG formulae. The GFR was measured in these donors with chromium labelled EDTA {[51Cr] EDTA). Bias was assessed by calculating the difference between the measured GFR and the calculated GFR using each of the two formulae; precision was calculated using the r value of the regression analysis. RESULTS: The group studied consisted of 90 donors, of whom 64 were males (71%). The mean age was 30.8 years (+/- 9.8) and mean BMI was 25.7 (+/- 5.7). The measured GFR (mean 112.4 +/- 17.5) correlated better with the calculated GFR by CG formula (mean 107.7 +/- 29.7) and showed poor correlation with the GFR estimated by the MDRD (mean 89.2 +/- 13.8); bias = 4.8 and 23.3, respectively (p = 0.1 and < 0.0001, respectively). The correlation with CG formula was better in males (bias = 2, p = 0.5) and those under 30 years of age (bias = 1.0, p = 0.9). Based on our data, we calculated a correction factor to the CG formula to improve the correlation with the measured GFR in Arab individuals. By multiplying the CG formula by 1.0446, the bias was reduced from 4.8 (p = 0.1) to 0.0 (p = 0.5) with an increase in precision from 0.2 (p = 0.05) to 0.43 (p = 0.0001). Using CG formula, the frequency for values within 30% of the mean of the measured value was 75%, which improved to 80% using the revised formula. CONCLUSIONS: CG formula was found to be the most appropriate for calculation of GFR in Arab individuals. It is possible to reduce the bias and improve precision in Arab individuals with normal renal function by multiplying the result obtained by CG formula by 1.0446.