Abstract: Objective To investigate the clinical efficacy and mechanism of oral sodium levothyroxine (LT4) in the treatment of intradialytic hypotesion (IDH) complicated with low thyroid hormone (TH) in maintenance hemodialysis (MHD) patients. Methods We recruited 40 MHD patients with IDH and low serum TH for at least 3 months during the period from June 2012 to June 2013. The relationship between serum TH level and IDH frequency in MHD patients was evaluated. The patients were then divided into two groups, LT4 treatment group (n=19) and control group (without LT4 treatment, n=18). Changes of IDH frequency and clinical parameters after the therapy for 24 weeks were observed in the two groups. LT4 was administrated orally 25μg/day for one week at the beginning, and then increased to 50μg/day for 24 weeks if no side-effects were found. LT4 should be reduced to 1/2～1/4 of the original dosage when side-effects were present, and should be terminated when serious adverse reactions occurred. Results Low serum TH level was found in 72.7% MHD patients with IDH. In the 40 MHD patients with IDH and low TH, free thyroxine (FT4) was negatively correlated with IDH frequency (R=-0.443, P=0.004). LT4 therapy terminated in 3 patients because of chest distress and palpitation in one case and no IDH anymore in 2 cases. In LT4 treatment group, IDH frequency reduced (0.10±0.052 vs. 0.20 ± 0.127, P=0.003) with the increases of free triiodothyronine (FT3) (4.63±0.765 vs. 3.84±0.697 pmol/l, P=0.003) and serum albumin (40.86±3.148 vs. 39.06±1.990 g/L, P=0.045), as compared with those in control group. Compared with the parameters before LT4 treatment, MHD patients after LT4 therapy showed the changes of FT4 (7.33 ± 1.190pmol/L, to 8.54 ± 1.399 pmol/L, P=0.009), FT3 (3.59 ± 0.603pmol/L to 4.63±0.765 pmol/L, P＜0.001), hemoglobin (69.89 ± 21.891 g/L to 82.61±11.49 g/L P=0.007), albumin (38.01±3.050g/L to 40.86±3.148 g/L, P=0.009), serum iron (7.26±3.27mmol/L to 9.39±1.56 mmol/L, P=0.006), left ventricular ejection fraction (49.32%±6.67% to 51.63%±6.87%, P=0.014), and IDH frequency (0.22±0.118 to 0.10±0.052, P＜0.001). Conclusion Oral LT4 therapy can reduce IDH frequency in MHD patients with low serum TH level. The effects of LT4 may relate to the increase of LVEF and improvement of anemia and nutrition status in these patients.

Key words: hemodialysis, thyroid hormone, intradialytic hypotension