Routine serum thyroid-stimulating hormone testing-optimizing pre-conception health or generating toxic knowledge?

Preconception thyroid-stimulating hormone levels and adverse pregnancy outcomes

OBJECTIVE

Evidence for the association between subclinical thyroid dysfunction before conception and its pregnancy outcomes is inconsistent. Thus, we evaluated the relationship between preconception thyroid-stimulating hormone (TSH) levels and adverse pregnancy outcomes.

DESIGN

Retrospective cohort study.

METHODS

A total of 50,217 women without prior thyroid disease who became pregnant within 1 year after undertaking a routine TSH test in the Chongqing Municipality of China (2010-2016) were studied. Restricted cubic spline regression and logistic regression were used to estimate the association between preconception TSH levels and pregnancy outcomes. The main outcomes were individual and composite adverse pregnancy outcomes (CAPOs) comprising pregnancy loss, small for gestational age, large for gestational age, and preterm birth.

RESULTS

Incidence of CAPO was 24.19%. Increased preconception TSH level was positively associated with CAPO (odds ratio [OR]/SD: 1.04, 95% confidence interval [CI]: 1.01-1.07) when TSH was ≥2.1 mIU/L, positively associated with pregnancy loss (OR/SD: 1.06, 95% CI: 1.01-1.12) when TSH was <2.1 mIU/L, negatively and positively associated with preterm delivery when TSH levels were <1.3 mIU/L (OR/SD: 0.90, 95% CI: 0.83-0.97) and >3.0 mIU/L (OR/SD: 1.08, 95% CI: 1.00-1.17), respectively. Women with subclinical hypothyroidism before conception were at a higher risk for CAPO (adjusted odds ratio [aOR]: 1.12, 95% CI: 1.04-1.22), while those with subclinical hyperthyroidism had a higher risk of preterm delivery (aOR: 1.31, 95% CI: 1.01-1.70).

CONCLUSIONS

Nonlinear associations were indicated between preconception TSH levels and pregnancy outcomes. Subclinical thyroid dysfunction before conception was associated with an increased risk of adverse pregnancy outcomes.

Effect of the Cut-Off Level for Thyroid-Stimulating Hormone on the Prevalence of Subclinical Hypothyroidism among Infertile Mexican Women

The primary aim of this study was to compare the prevalence of subclinical hypothyroidism (SCH) using two different cut-off levels for TSH values (≥2.5 mIU/L versus ≥4.1 mIU/L). The secondary objective was to analyze the clinical-biochemical characteristics in women with and without SCH. This was a retrospective cross-sectional study. In total, 1496 Mexican women with infertility were included: Group 1, women with TSH levels ranging between 0.3 and 2.49 mIU/L, n = 886; Group 2, women with TSH between 2.5 and 4.09 mIU/L, n = 390; and Group 3, women with TSH ≥4.1 mIU/L n = 220. SCH prevalence was 40.7% (CI 95%: 38.3-43.3%) with TSH cut-off ≥ 2.5 mIU/L, and 14.7% (CI 95%: 12.7-16.5%) with TSH cut-off ≥ 4.1 mIU/L, (p = 0.0001). The prevalence of overweight was higher in Group 2 than in Groups 1 and 3. Thyroid autoimmunity, obesity and insulin resistance were higher in Group 3 than in Group 1 (p < 0.05). No other differences were observed between groups. Conclusions: The prevalence of SCH in our selected patients increased almost three times using a TSH cut-off ≥ 2.5 mIU/L compared with a TSH cut-off ≥ 4.1 mIU/L. Women with TSH ≥4.1 mIU/L compared with TSH cut-off ≤ 2.5 mIU/L more often presented with obesity, thyroid autoimmunity and insulin resistance.

Controversial Screening for Thyroid Dysfunction in Preconception and Pregnancy: An Evidence-Based Review

Objective: To evaluate the recommendations on the most adequate screening method (universal or selective) for thyroid dysfunction. Although thyroid dysfunction is a common disorder in fertile women and untreated cases may have negative maternal, fetal and neonatal outcomes, its screening in preconception and early pregnancy is controversial.

Materials and methods: An evidence-based review was conducted to identify publications since 2017 of American Thyroid Association (ATA) guidelines, according to the following Population, Intervention, Comparison, Outcomes and Study (PICOS): women in preconception or pregnancy without thyroid disease who underwent universal or selective screening for thyroid dysfunction. Study selection obeyed the PRISMA criteria.

Results: We included 15 of 325 publications. The 2017 ATA guidelines recommend selective screening in both preconception and pregnancy. The only two reviews on preconception recommended universal screening. For pregnancy, nine articles suggested universal screening, while a prospective study advocated selective screening. The main benefits advocated for universal screening were easy and low-cost tests; absence of missed diagnosis; safe and inexpensive treatment and its potential in preventing negative outcomes. Iodine deficiency is a decisive indication, but it was not evaluated in all clinical studies. Screening harms and knowledge gaps were the main arguments against universal screening. There are very few cost-effectiveness studies.

Conclusion: We recommend universal screening for thyroid dysfunction in early pregnancy, which is a distinct point of view from 2017 ATA guidelines (weak recommendation, low-quality evidence). It is not possible to make a formal recommendation for preconception (insufficient evidence). We strongly suggest an individualized analysis by each country.

Infertility management in primary care

Infertility is a growing issue for couples. Primary care NPs can manage initial treatment as well as address the emotional and financial burdens of patients experiencing infertility. NPs can provide timely access to investigations and treatment, helping patients achieve their goal of pregnancy sooner.

Levothyroxine supplementation on assisted reproduction technology (ART) outcomes in women with subtle hypothyroidism: a retrospective study

The need for treating subclinical hypothyroidism (SCH) in women undergoing assisted reproduction technology (ART) is under debate. Moreover, it is known that controlled ovarian hyperstimulation (COH) protocols may impair the thyroidal axis. Therefore, we evaluated if levothyroxine (L-T4) supplementation in SCH women before undergoing ART positively affects the main reproductive outcomes. We retrospectively analyzed in vitro fertilization (IVF) data of 4147 women submitted to 6545 cycles in a tertiary care IVF Center (January 2009-December 2014). L-T4 (1.4-2.0 mcg/kg) treatment was offered to all women with a pre-cycle TSH >2.5 mIU/L before starting COH and main ART outcomes were compared in euthyroid and L-T4-treated women undergoing ART. Among 4147 women, 1074 (26%) were affected by SCH and were treated with L-T4 before COH was started. No statistically significant differences among L-T4-treated and euthyroid women group were observed regarding pregnancy rate, respectively, per cycle (27.67% vs 26.37%; p = .314) and per embryo transfer (30.13% vs 29.17%; p = .489), live birth rate, respectively, per cycle (21.58% vs 20.38%; p = .304) and per embryo transfer (23.49 vs 22.54%; p = .449) and the rest of primary and secondary efficacy endpoints. Early L-T4 treatment for infertile women with a subtle thyroid dysfunction may mitigate and protect from the negative effects of SCH in the setting of ART, and may preventively overcome also the negative impact of COH on thyroidal axis.

Meta-analysis of ART outcomes in women with different preconception TSH levels

BACKGROUND

To assess whether elevated thyroid-stimulating hormone (TSH) levels before conception can predict poor outcomes of assisted reproductive technology (ART).

METHODS

Prior to July 2018, we searched the PubMed, EMBASE, COCHRANE, Google Scholar, and CNKI databases for studies. Retrospective or prospective reports that compared ART results in patients with subclinical hypothyroidism (SCH) with normal thyroid function were selected. Two reviewers separately reviewed each potential article for qualification, analyzed the quality of the studies according to the Newcastle-Ottawa scale, and extracted the data. The PRISMA guidelines were adopted.

RESULTS

We selected a total of 18 publications that included 14,846 participants for this meta-analysis. When the TSH cut-off value for SCH was set at 2.5 mIU/L, no significant differences were observed in ART-related outcomes between SCH patients and normal women. The evaluated outcomes included the live birth rate (LBR) (OR: 0.93; 95% CI (0.77,1.12), P = 0.43), clinical pregnancy rate (CPR) (OR:1.02; 95% CI (0.90,1.17); P = 0.74), pregnancy rate (PR) (OR: 1.00; 95% CI (0.89,1.12); P = 0.99), and miscarriage rate (MR) (OR:1.24; 95% CI (0.85, 1.80); P = 0.26). Furthermore, when a higher TSH level was used as the cut-off value to diagnose SCH (i.e., 3.5-5 mIU/L), a significant difference was found in the MR (OR: 1.91; 95% CI (1.09, 3.35); P = 0.02) between the two groups of ART-treated women. However, when a broader cut-off value was used to define SCH, no significant differences were observed in the LBR (OR: 0.72; 95% CI (0.47,1.11); P = 0.14), CPR (OR: 0.82; 95% CI (0.66,1.00); P = 0.052), or PR (OR: 1.07; 95% CI (0.72,1.60); P = 0.74) between the two groups of ART-treated women.

CONCLUSION

No difference was observed in ART outcomes when a TSH cut-off value of 2.5 mIU/L was used. However, when a broader TSH cut-off value was used, preconception SCH resulted in a higher miscarriage rate than in normal women.