A Study of Thyroid Dysfunction in Patients with End Stage Renal Disease on Hemodialysis

Abstract

Background: Progression of chronic kidney disease (CKD) is associated with having a number of complications, including thyroid dysfunction. CKD affects the thyroid function by lowering levels of circulating thyroid hormones, interfering with hormones binding to protein carriers, disrupting metabolism and elimination of thyroid hormones.Aim of the study: We aimed to evaluate and compare thyroid functions among patients on chronic hemodialysis (HD) and healthy participants. Methods: This is a cross- sectional study conducted in the dialysis unit of Baghdad teaching hospital from ( May 2015 to November 2015). A total of 45 known CKD cases (stage 5) older than 18 year were included in the study. Patients with known thyroid disorders, on medications affecting thyroid function were excluded from the study. All subjects were clinically euthyroid, they were investigated with laboratory tests to determine blood urea, serum creatinine, body mass index, estimated glomerular filtration rate (eGFR), thyroid function including: serum triiodothyronine (T3), thyroxin (T4), free T3, free T4, and thyroid- stimulating hormone (TSH).Results were compared with the same measurements in 20 normal subjects as a control group.Results: Of total sample of patients, 22(48.9%) were male, 23(51.1%) were female; with mean age of 50.96± 14.26 years. In control group; 12 (60%) were male, 8 (40%) were female with mean age of 40.25± 11.86 years. In HD group; we found statistically significant lower mean values of T3 (1.54± 0.67, p= 0.009), free T3 (2.65± 0.92, p <0.001), and higher frequency of low T3 syndrome in 73. 33% (n=33) vs. 5% (n= 1) with (p <0.001). Subclinical hypothyroidism was found in control group only, in  20% (n= 4), (p <0.001). There was a strong correlation between S. creatinine with free T_3, correlation coefficient (- 0.378). In patients on HD for equal or more than a year; we found statistically significant lower mean values of T3 (1.07± 0.23) vs. (1.66± 0.69), (p= 0.016), in spite of significant increase in mean eGFR of (9.00± 4.82) vs. (6.39± 3.08), (p= 0.05). There was a statistically significant association between total T₄ and presence of DM, (P=  0.044).Conclusions: We observed that functional thyroid gland disorders are more common among patients on chronic hemodialysis compared with healthy subjects, and reveal their link with time on dialysis. Low T3 syndrome (Euthyroid sick syndrome)is the most frequently thyroid function disorder.

Keywords: Triiodothyronine, Hemodialysis, Low T3syndrome, Euthyroid sick syndrome.