Comparison of thyroid hormone abnormalities among men with primary and secondary infertility: a cross-sectional study in Benin City, Nigeria.

Objective: Male infertility can be primary or secondary, depending on whether pregnancy has been achieved before or not, but thyroid gland involvement is rarely investigated in the laboratory work-up. This study aimed to assess thyroid hormone abnormalities among primary and secondary infertile men.

Design: This is a cross-sectional study involving male partners of infertile couples presenting at the fertility clinic with an established diagnosis of infertility after review by the clinician. Males with proven fertility served as controls.

Setting: The study was conducted at the Human Reproduction and Research Programme unit and the Chemical Pathology Laboratory of the University of Benin Teaching Hospital, Benin City, Edo State, Nigeria.

Participants: This study involved 200 participants who consisted of 50 controls (fertile men) and 150 infertile men (80 primary infertile men and 70 secondary infertile men). The participants were reviewed by a clinician, and a semen analysis was done to ascertain their fertility status.

Results: The results show that sperm indices, such as sperm count, total motility, progressive motility, viable sperm cells, normal forms and volume were significantly lower (p<0.001) while non-viable sperm cells and abnormal forms were significantly higher (p<0.001) in both primary and secondary infertile males than controls. The mean triiodothyronine and thyroxine values were significantly higher (p<0.001), while thyroid-stimulating hormone was lower (p<0.001) among primary infertile males than secondary infertile men. Some 33/80 (41.3%) primary infertile men had thyroid abnormalities (5 subclinical hypothyroidism and 28 overt hypothyroidism), while 55/70 (78.6%) secondary infertile men had thyroid abnormalities (6 subclinical hypothyroidism and 49 overt hypothyroidism).

Conclusion: Thyroid abnormalities were more predominant among secondary infertile men than primary infertile men in this study.