Initial side effects of roxadustat on thyroid function in patients undergoing hemodialysis

Roxadustat, a hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitor, is effective for treating renal anemia, with efficacy noninferior to erythropoiesis-stimulating agents. However, data on its adverse effects remain scarce. In medical practice, roxadustat administration reportedly leads to central hypothyroidism; however, the frequency of its occurrence remains unclear. We investigated thyroid function in patients undergoing dialysis who received roxadustat at Saiseikai Yokohamashi Tobu Hospital, with particular focus on the timing of the decrease in serum thyroid-stimulating hormone (TSH) levels after roxadustat initiation and the subsequent course of thyroid function. HIF-PH inhibitors were administered to 43 chronic kidney disease patients including dialysis. After 2 weeks of roxadustat administration, we extracted the data of 16 hemodialysis patients who exhibited absence of residual urine and were able to undergo blood tests. All patients revealed decreased serum TSH levels. In contrast, changes in serum free triiodothyronine and free thyroxine levels were minor. None of the patients reported fatigue, bradycardia, or constipation, which are common symptoms of hypothyroidism. Our findings revealed that roxadustat may cause TSH reduction after 2 weeks of administration, though some patients showed subclinical hypothyroidism with high TSH levels. In a few cases, TSH levels decreased to one-tenth of the normal values. Despite these rapid changes, none of the patients exhibited clinical symptoms. Hence, regular thyroid hormone level monitoring is necessary with roxadustat administration, regardless of patients' history of thyroid function.