Unexplained infertility (UI), defined as the inability to conceive after 12 months of unprotected intercourse with no diagnosed cause, affects 10% to 30% of infertile couples. An improved understanding of the mechanisms underlying UI could lead to less invasive and less costly treatment strategies. Abnormalities in thyroid function and hyperprolactinemia are well-known causes of infertility, but whether thyrotropin (TSH) and prolactin levels within the normal range are associated with UI is unknown.
Objective
To compare TSH and prolactin levels in women with UI and women with a normal fertility evaluation except for an azoospermic or severely oligospermic male partner.
DESIGN, SETTING, AND
Participants
Cross-sectional study including women evaluated at a large academic health system between 1 January 2000 and 31 December 2012 with normal TSH (levels within the normal range of the assay and ≤5 mIU/L) and normal prolactin levels (≤20 ng/mL) and either UI (n = 187) or no other cause of infertility other than an azoospermic or severely oligospermic partner (n = 52).
Main Outcome Measures
TSH and prolactin.
Results
Women with UI had significantly higher TSH levels than controls [UI: TSH 1.95 mIU/L, interquartile range: (1.54, 2.61); severe male factor: TSH 1.66 mIU/L, interquartile range: (1.25, 2.17); P = 0.003]. This finding remained significant after we controlled for age, body mass index, and smoking status. Nearly twice as many women with UI (26.9%) had a TSH ≥2.5 mIU/L compared with controls (13.5%; P < 0.05). Prolactin levels did not differ between the groups.
Conclusions
Women with UI have higher TSH levels compared with a control population. More studies are necessary to determine whether treatment of high-normal TSH levels decreases time to conception in couples with UI.
PMID 29272395 29272395 DOI 10.1210/jc.2017-02120 10.1210/jc.2017-02120 Orouji Jokar et al. 2017, Orouji Jokar 2017
Cite this article
Orouji Jokar, T., Fourman, L. T., Lee, H., Mentzinger, K., & Fazeli, P. K. (2018). Higher TSH Levels Within the Normal Range Are Associated With Unexplained Infertility. The Journal of clinical endocrinology and metabolism, 103(2), 632-639. https://doi.org/10.1210/jc.2017-02120
Orouji Jokar T, Fourman LT, Lee H, Mentzinger K, Fazeli PK. Higher TSH Levels Within the Normal Range Are Associated With Unexplained Infertility. J Clin Endocrinol Metab. 2018;103(2):632-639. doi:10.1210/jc.2017-02120
Orouji Jokar, Tahereh, et al. "Higher TSH Levels Within the Normal Range Are Associated With Unexplained Infertility." The Journal of clinical endocrinology and metabolism, vol. 103, no. 2, 2018, pp. 632-639.
Moon KY et al., 2023·Taiwan J Obstet Gynecol·
Open Access
This study aimed to investigate the impact of thyroid autoantibodies and serum TSH levels on clinical IVF outcomes. This study included 260 Korean women scheduled for their first IVF between 2013 and 2017. Serum levels of thyroid hormone, TSH, and antibody for thyroid peroxidase and thyroglobulin were measured just before the first ovarian stimulation. Clinical pregnancy rate (PR), ongoing PR, and miscarriage rate were analyzed according to thyroid autoimmunity and serum TSH levels. The primary outcome was ongoing PR beyond 12 weeks of gestation. The ongoing PR and miscarriage rates were similar between women with positive (n = 29) and negative autoantibodies (n = 186). In women with subclinical hypothyroidism (serum TSH ≥4.2 μIU/mL), ongoing PR was significantly lower than euthyroid women (22.2%, vs. 44.7%, p = 0.045), but miscarriage rate was similar. The group with serum TSH ≥3.4 μIU/mL showed a significantly lower ongoing PR (23.9% vs. 46.7%, p = 0.005) and significantly higher miscarriage rate (38.9% vs. 14.1%, p = 0.020). In multivariate logistic regression analysis, serum TSH ≥3.4 μIU/mL was an independent unfavorable predictor for ongoing PR (odds ratio 0.375, p = 0.013). Thyroid autoantibodies did not affect clinical IVF outcomes, but women with serum TSH ≥3.4 μIU/mL demonstrated poor IVF outcomes.
Vissenberg R et al., 2016·Eur J Obstet Gynecol Reprod Biol·
Thyroid dysfunction has been described as a possible risk factor for having an abnormal fetal position at birth. In this study we aim to determine the association between thyroid function in early pregnancy and breech presentation at term. We used data from the Amsterdam Born Children and their Development (ABCD) cohort. 3347 pregnant women were included between January 2003 and March 2004 in Amsterdam, the Netherlands. Thyroid function tests were performed between 5 and 37 weeks gestational age (median 12.9 weeks). The main outcome measure was the association between thyroid function in early pregnancy and breech presentation at term. Univariate and multivariate analysis were performed to determine the association between thyroid function and breech presentation. Increased TSH in pregnancy, defined as thyroid stimulating hormone (TSH) >97.5th percentile (>3.53mIU/L), was associated with a higher risk for breech presentation at term (aOR 2.32, CI 1.1-4.8, p=0.02) compared to euthyroidism (TSH between 2.5th and 97.5th percentile). After exclusion of overt hypothyroidism and hyperthyroidism the aOR was 2.34 (CI 1.1-5.0, p=0.03). Trimester specific analysis showed a significant association of increased TSH levels (>3.68mIU/L) in the second trimester with breech presentation (aOR 3.7, CI 1.7-7.8, p=0.001). In the second trimester low free thyroxine (FT4) <2.5th percentile (<6.7pmol/L) was also associated with breech presentation (aOR 2.5, CI 1.0-6.3, p=0.04). Increased TSH and decreased FT4 in the second trimester of pregnancy are associated with an increased risk for breech presentation at term. The association of abnormal thyroid parameters in the first of third trimester is still unclear.
Metabolic and Endocrine Agents · Thyroid Replacement
Thyroid disease in general, and hypothyroidism in particular, are very common in women. In the USA, the most common cause of primary thyroid deficiency is on an autoimmune basis due to lymphocytic (Hashimoto) thyroiditis. Because there are thyroid hormone receptors in virtually every tissue of the body, the manifestations of hypothyroidism are varied, but problems with abnormal menses, conception, fertility, and pregnancy can be especially troubling in young women. The single most important diagnostic test is measurement of serum thyrotropin (TSH). The overwhelming majority of patients with hypothyroidism are treated with a single daily dose of synthetic levothyroxine with the goal of therapy being restoration of a normal metabolic state with return of the TSH level down to the range of 0.5 to 1.5 mlU/L. "Subclinical" hypothyroidism refers to those patients with early or mild thyroid hypofunction manifested as slight elevations of thyrotropin (approximately 4-10 mlU/L) although serum thyroxine (T4) and triiodothyronine (T3) levels are within their reference ranges. The entity is somewhat controversial in regard to its consequences if left untreated, and whether or not we should be screening patients, at least susceptible populations, for the condition. Reports indicate an association between subclinical hypothyroidism and poor outcomes of pregnancy, as well as dyslipidemias, atherogenesis, and increased mortality in the long term. We believe these consequences are sufficiently compelling to warrant screening and treatment with levothyroxine when found to halt progression to overt hypothyroidism, and improve symptoms, pregnancy outcomes, lipid abnormalities, and cardiovascular function. Obstetricians & Gynecologists, Family Physicians. After completion of this article, the reader should be able to recall that hypothyroidism is a common disease in women, has many protean manifestations, and can be successfully diagnosed and treated; explain that the condition of subclinical hypothyroidism can be diagnosed and if treated can prevent many untoward complications; and state that there should be heightened awareness of the disease so that proper screening tests can be performed.
Thyroid and Metabolic Function · Thyroid Disorders
Hilgers TW, 2004·The Medical and Surgical Practice of NaProTECHNOLOGY·
Both overt and subclinical thyroid dysfunction are recognized in NaProTECHNOLOGY as significant causes of cycle-level reproductive abnormalities -- including oligomenorrhea, anovulation, luteal phase deficiency, heavy bleeding, and recurrent early pregnancy loss -- detectable through CrMS charting before standard screening would prompt thyroid evaluation. The chapter advocates comprehensive thyroid assessment (TSH, free T4, free T3, and thyroid antibodies) with fertility-optimized reference thresholds in women presenting with cycle disorders or infertility, followed by reassessment of CrMS patterns and hormone profiles after thyroid correction to identify and treat any residual follicular or luteal phase defects.