Relation Between Thyroid Hormones and Insulin Resistance in Hemodialysis Patients

Insulin resistance (IR) is a common problem in patients with ESRD on regular HD, and it is related to many complications, including cardiovascular complications, the major killer in these patients. Disorders of thyroid function are common in patients with ESRD. Many factors have been claimed to contribute to IR in HD patients. Our aim is to study the relations between thyroid hormones and IR in HD patients for better understanding and management of IR. The study involved 35 patients with ESRD under regular HD (group 1) and 20 normal control subjects (group 2). All of them underwent complete history taking and clinical examination: biochemical and hematological, thyroid hormones TSH, free T3 (FT3) and free T4 (FT4), and insulin resistance using the homeostasis model assessment (HOMA-IR). Patients with DM and those with known thyroid disorders were excluded from the study. Comparing HD patients and normal control subjects shows significant differences as regards FT3 (p=0.04) 33.58±12.14 vs. 40.63±11.27 pg/l, respectively; TSH (p=0.03) 3.29±3.83 vs. 1.80±0.88 mu/l, respectively; fasting insulin level (p<0.001) 30.1±6.05 vs. 10.68±2.77 mu/ ml, respectively; HOMA (p<0.001) 6.72±1.41 vs. 2.4±0.67, respectively. There is no significant difference as regards FT4 (p=0.36) 15.17±6.72 vs. 16.35±2.66 pmol/l, respectively. Bivariate correlation in HD patients shows HOMA IR correlates with FT3 (p<0.001), FT4 (p<0.001), TSH (p<0.001), HDL (p<0.001), and hematocrit (p<0.001). No correlations were found with BMI, age, total cholesterol, LDL, or triglycerides. Linear regression analysis showed HOMA-IR was independently determined by HDL (p=0.04), hematocrit (p=0.02), and TSH (p=0.008). IR is very common in HD patients. There is a close correlation between IR and thyroid hormones. TSH, HDL, and hematocrit levels independently determine IR. Regular follow-up of these factors is necessary for proper management of IR.