Effect of Thyroxine Replacement on Leydig Cell and Sertoli Cell Function in Men with Hypothyroidism

Thyroid hormones play an important role in reproductive and sexual function in both sexes. Comprehensive information on the ill-effects of hypothyroidism on Leydig cell, Sertoli cell and germ cell function is lacking in the existing literature.

To investigate the effect of primary hypothyroidism and its treatment on testicular function - Sertoli cell, Leydig cells, seminal fluid and spermatozoa.

This study was carried out as a descriptive study with a before-after study design in the endocrine department of a tertiary care hospital in South India. Forty treatment naïve, overtly primary hypothyroid, consenting male patients were included. Hormones assessed were free T3, free T4, thyroid stimulating hormone, follicle stimulating hormone [FSH], luteinizing hormone [LH], prolactin, testosterone, inhibin B[INHB], and insulin like factor 3[INSL3]. Semen analysis was done according to WHO 2010 guidelines in 37 subjects. Sexual function questionnaires like Androgen Deficiency in Aging Male [ADAM], and Arizona Sexual Experience Scale [ASEX] were used. After ensuring euthyroid state for consecutive 6 months with adequate dose of thyroxine sodium, reassessment of all parameters was done.

At baseline, 72.5 % had a low serum testosterone value (< 230 ng/dl), 67.56 % had low total sperm motility, 72.97% had low total progressive sperm motility, 80% had low ADAM score and 72.72% had low ASEX score. A raised prolactin level was seen in 32.5% of study subjects. Hypogonadotropic hypogonadism was more common than hypergonadotropic hypogonadism (89.66% vs. 10.34%). On restoration of euthyroidism, all these parameters improved. Serum INSL3 and LH increased significantly after thyroxine replacement, unlike FSH and INHB.

Leydig cell function seemed more severely affected by hypothyroidism as compared to Sertoli cell function. Among sperm function parameters, motility was predominantly affected.