Sub-clinical hypothyroidism and hyperprolactinemia in infertile women: Bangladesh perspective after universal salt iodination

摘要

Background: Hypothyroidism is an accepted cause of infertility and habitual abortion. We therefore evaluated the status of thyroid function and related hormones in infertile women in Bangladesh. Methods: Serum thyroid stimulating hormone and prolactin was measured in 113 infertile women during their first visit for infertility evaluation. Results: Prevalence of sub-clinical hypothyroidism was 6.5% and 15%, and prevalence of hyperprolactinemia was 43% and 21% in primary and secondary infertility respectively. Mean TSH level was higher in secondary infertility (3.6 +/- 3.7mIU/L) than primary infertility (2.3 +/- 2.7mIU/L), though the difference was not statistically significant (P < 0.11). Mean prolactin level in primary infertility (495 +/-340nmol/L) was higher than secondary infertility (340 +/- 310nmol/L), showing a significant statistical difference (p<.05). Conclusion: Prevalence of hyperprolactinemia was higher in primary infertility and prevalence of sub-clinical hypothyroidism was higher in secondary infertility, showing no correlation between TSH and prolactin levels in these two groups. Declaration This paper was presented as poster in the 9 th World Congress of Nuclear Medicine and Biology (WCNMB), 22-27 th Oct. 2006, Seoul. Korea. Introduction Infertility is defined as the inability to conceive after one year of regular intercourse without contraception. The prevalence of infertility is estimated at between 12 and 14% and has remained stable in recent years. It thus represents a common condition, with important medical, economic and psychological implications. Sub fertility affects one in seven couples in the United Kingdom and is associated with considerable patient stress and anxiety. According to standard protocol, infertility evaluation usually identifies different causes, including male infertility (30%), female infertility (35%), the combination of both (20%), and finally unexplained or “idiopathic” infertility (15%). Thyroid dysfunction is a condition known to reduce the likelihood of pregnancy and to adversely affect pregnancy outcome. Data on the relationship between thyroid disorders and infertility remain scarce and the association with a particular cause of infertility has not been thoroughly analyzed.[1],[2] Prolactin is a polypeptide hormone secreted by the anterior pituitary gland, whose main role is the stimulation of lactation in the postpartum period. The increase in prolactin secretion can be physiological (pregnancy and lactation) or pathological (hypothalamic and pituitary diseases, iatrogenic, etc.). Hyperprolactinemia induces suppression of the hypothalamic-pituitary-gonadal axis and resistance of the ovary to gonadotropin action, which results in amenorrhea and lack of ovulation. Infertility associated with hyperprolactinemia is reversible with treatment, irrespective of the type of treatment (radical or medical). Lowering of prolactin levels to normal or near normal is often necessary to allow ovulation.[3]Traditionally, measurements of prolactin and thyroid stimulating hormone have been considered important components of the evaluation of women presenting with infertility.[4] Hypothyroidism in females, maternal hypothyroidism and sub-clinical hypothyroidism, have all came under a lot of discussion recently. The association of iodine deficiency disorder (IDD) with hypothyroidism is a well-established phenomenon. The prevalence of sub-clinical thyroid disorders in infertility patients and indications for treatment have been discussed, but no consensus has been obtained. Mymensingh is a district town about 120 km north of Dhaka, and an endemic zone for iodine deficiency in Bangladesh. As it is an iodine-deficient zone with an iodine supplementation program after a law was passed by parliament in 1989 requiring universal iodination of salt by 1996, our group was interested to look at the current status of thyroid function and related hormones in primary and secondary infertility patients. The ai