The functional state of the thyroid gland in patients with end-stage renal disease on program hemodialysis

Background. The prevalence of subclinical hypothyroidism among patients with chronic kidney disease (CKD) reaches 30%. To date, recommendations for the detection and treatment of thyroid dysfunction in patients on program hemodialysis (PHD) have not been developed. The clinical significance of the detected changes in thyroid function parameters is disputed. In most studies, the «low T3» syndrome is associated with the severity of the patient’s condition and high mortality.

Objective. Evaluation of the indicators of thyroid status in patients with end-stage renal disease (ESRD) on PHD and compare the identified changes with the adequacy of hemodialysis.

Methods. The study included 180 ESRD patients on PHD. A cross-sectional study was carried out to evaluate the indicators of the functional state of the thyroid gland in ESRD patients on PHD. Creatinine, blood urea nitrogen, thyroid-stimulating hormone (TSH), fT3, fT4 and thyroperoxidase antibody, levels were determined in all patients. The efficiency of hemodialysis was calculated using the Daugirdas formula (Kt/V).

Results. 81 (45%) women and 99 (55%) men underwent examination Women were significantly older than men (p=0.005). In the group of examined patients on PHD, there were 25% (n=45) of patients with glomerular kidney pathology, 25% (n=45) – with tubulointerstitial diseases, 10% (n=18) of patients with cystic kidney disease, 10% (n= 18) – with glomerular lesions in diabetes mellitus, 11.7% (n=21) – with glomerular lesions in systemic connective tissue diseases, 18.3% (n=33) of patients with rare forms of kidney disease. The duration of hemodialysis of the examined patients ranged from 0 to 35 years. The median duration of hemodialysis was 5.0 (2.0–9.0) completed years (no significant difference was found in the duration of hemodialysis between men and women). In 20.6% (n=37) of patients, an increase in TSH levels was detected, in 5.5% (n=10) – a decrease in TSH levels, 73.9% (n=133) of patients were in a state of euthyroidism. An increase in antithyroid antibodies was detected in 11.7% of patients. Attention was drawn to the higher value of fT4 in the group with high TSH compared with low TSH (P=0.036). In 33.9% of patients, «low T3» syndrome was detected. There was a significant difference in the fT4 level in the group with normal and reduced fT3 (P<0.001). In patients with «low T3» syndrome, the blood urea nitrogen level after hemodialysis was significantly higher, which indirectly may indicate insufficient effectiveness of hemodialysis (P=0.021). There were significantly fewer patients with adequate hemodialysis in the group of patients with low T3 levels (P=0.009).

Conclusion. Thyroid dysfunction is often detected in patients on PHD. A decrease in the functional activity of the thyroid gland reduces the effectiveness of hemodialysis procedures. Additional studies are required to develop algorithms for the detection and treatment of thyroid dysfunction in patients on PHD.