Levothyroxine therapy in children with hypothyroidism due to frequently relapsing nephrotic syndrome: an observational cohort study

Abstract Background : Although the prevalence of temporary hypothyroidism (HT) in nephrotic syndrome (NS) is high, there is conflict over hormone replacement therapy in these cases. In an observational cohort with a control group, we investigated the potential benefits of hormone replacement therapy in patients with frequently relapsing nephrotic syndrome (FRNS) and HT. Methods : Consecutive 2–13-year-old patients with FRNS and thyroid stimulant hormone (TSH) higher than 5.5 mIU/L were studied. Following relapse treatment, patients treated with levothyroxine were considered the levothyroxine group. The incidence of relapses was the primary outcome. Secondary outcomes were the cumulative dose of prednisolone, the number of treatment failures, and the duration of each relapse. Results : Thirty-two relapses per 27.2 person-years and 45 per 29.2 person-years occurred in the levothyroxine and control groups, respectively. The relapse rate was 1.17 versus 1.53 with the incidence rate ratio of 0.76 (95%Cl: 0.46- 1.22; p=0.24). The mean dose of prednisolone and time to remission was significantly lower in the levothyroxine group compared to the controls (0.51 ± 0.40 versus 0.55 ± 0.50 mg/kg/day; p=0.03 and 6.0 ± 2.17 versus 9.7 ± 2.87 days; p<0.001, respectively). There was a significant difference in the levels of TSH, free thyroxine (FT4), albumin, and creatinine. This significant difference disappeared during remission for albumin but remained significant for TSH and creatinine. Conclusion : In patients with FRNS, the administration of levothyroxine can reduce the time to remission and dose of prednisolone. However, it has no significant effect on relapse rate and treatment failure.