Comparative Study of Peripheral Thyroid Hormone Homeostasis Disturbance in the Diabetic and Non-Diabetic Hemodialytic Patients

Chronic kidney disease (CKD) is a leading cause of death and morbidity in developed countries. Although recent studies have shown that the prevalence of thyroid disorders is higher in individuals with CKD, the underlying mechanisms are not clear. Therefore, this study aimed to evaluate the blood levels of thyroid hormones in diabetic (diabetes type 2) and non-diabetic patients with end-stage renal disease under hemodialysis treatment.

Thyroid-stimulating hormone (TSH), 3, 5, 3', 5'-tetraiodothyronine (T4/thyroxine), and 3, 3', 5-triiodothyronine (T3), were measured. Furthermore, kidney function tests (urea and creatinine), uric acid, serum lipid profile, and fasting blood glucose were measured using spectrophotometry-based methods.

There was no significant difference between the hemodialytic-diabetic subjects (HDS) and hemodialytic-non-diabetic subjects (HNDS) regarding the levels of thyroid function hormones, including TSH, T4, and T3. However, the ratio of triiodothyronine (T3) to thyroxine (T4) (T3/T4 ratio) was significantly different between the HDS and HNDS (P<0.05). These ratios (mean±standard error of the mean) were obtained at 0.220±0.026 and 0.554±0.12 in female HDS and HNDS, respectively. On the other hand, regarding males, these ratios were determined at 0.205±0.01 and 0.295±0.05 in HDS and HNDS, respectively.

Homeostasis disturbance in the T3/T4 ratio hemostasis is present in HDS, compared to HNDS; however, it is not related to the hypothalamic-pituitary-thyroid axis. Peripheral factors, including the activities of iodothyronine deiodinase type 1 and type 2 enzymes, which are involved in regulating serum levels and converting T4 to T3, are probably responsible for the observed differences.