Levothyroxine for a high‐normal TSH in unexplained infertility

Abstract

AbstractObjectiveUnexplained infertility affects nearly one‐third of infertile couples. Women with unexplained infertility are more likely to have a high‐normal thyroid‐stimulating hormone level (TSH: 2.5–5 mIU/L) compared to women with severe male factor infertility. Practice guidelines vary on whether treatment should be initiated for TSH levels >2.5 mIU/L in women attempting conception because the effects of treating a high‐normal TSH level with levothyroxine are not known. We evaluated conception and live birth rates in women with unexplained infertility and high‐normal TSH levels.Design, Patients and MeasurementsRetrospective study including 96 women evaluated for unexplained infertility at a large academic medical centre between 1 January 2000 and 30 June 2017 with high‐normal TSH (TSH: 2.5–5 mIU/L and within the normal range of the assay) who were prescribed (n = 31) or not prescribed (n = 65) levothyroxine. Conception and live birth rates were assessed.ResultsThe conception rate in the levothyroxine group was 100% compared to 90% in the untreated group (p = .086 unadjusted; p < .05 adjusted for age; p = .370 adjusted for TSH; p = .287 adjusted for age and TSH). The live birth rate was lower in the levothyroxine group (63%) compared to the untreated group (84%) (p = .05 unadjusted; p = .094 adjusted for age; p = .035 adjusted for TSH; p = .057 adjusted for age and TSH).ConclusionsWomen with unexplained infertility and high‐normal TSH levels treated with levothyroxine had a higher rate of conception but lower live birth rate compared to untreated women, with the limitation of a small sample size. These findings assert the need for prospective, randomized studies to determine whether treatment with levothyroxine in women with unexplained infertility and high‐normal TSH is beneficial.