Diagnosis, treatment, and management of gestational hypothyroidism. The TIROGEST study

Reference ranges of thyroid hormones during the first trimester in Catalan women using the Atellica® IM Solution Immunoassay Analyzer

BACKGROUND

Gestational hypothyroidism has been shown to be associated with adverse pregnancy outcomes as well as adverse outcomes for the child. Thyroid hormones concentrations change in gestation, especially within the first trimester, so the results of thyroid function test often are outside non-pregnant reference ranges. The objective of this study was to establish the first trimester reference ranges for thyroid stimulating hormone (TSH) and free thyroxine (FT4) for pregnant women in Barcelona (Spain).

METHODS

It was a prospective study in which 673 women were recruited during their first trimester of gestation (8-13 weeks). Serum TSH, FT4 and antithyroid peroxidase antibodies (TPOAb) were measured with Atellica® IM 1600 (Siemens Healthineers). After excluding 418 women, the reference ranges for TSH and FT4 were calculated by the 2.5th and 97.5th percentiles. Potential variables examined in this study were age, body mass index (BMI), ethnicity, iodine supplementation and smoking habit.

RESULTS

The reference ranges established on the Atellica® IM 1600 for the first trimester pregnancy in our population were 0.111 to 4.291 mIU/L for TSH and 11.45 to 17.76 pmol/L for FT4. No significant differences were found in thyroid hormones concentrations regarding maternal age (≤30 years vs >30 years) (p = .117), iodine supplementation (p = .683) and smoking habit (p = .363). The prevalence of TPOAb was estimated at 10.0%.

CONCLUSIONS

We found that in our local population, the optimal TSH upper reference limit in the first trimester of gestation was 4.3 mIU/L, similar to that proposed by de ATA-2017 guideline (4.0 mIU/L).

Iodine status in pregnant women in northern Spain. Effect of iodised salt and iodine supplements on thyroid function

INTRODUCTION

Iodine deficiency is linked to thyroid dysfunction, particularly in pregnant women. The objective of this study was to ascertain the iodine levels of women in the second trimester of pregnancy, analysing the influence of iodine ingestion on urinary iodine concentration (UIC) and maternal thyroid function.

METHODS

A prospective observational study of pregnant women from Health Area IV of Asturias (northern Spain) recruited before 13 weeks of gestation between May and June 2017. A questionnaire on iodine intake was completed at the first visit, and urine and serum samples were collected at baseline and again during the second trimester. UIC, thyroid stimulating hormone (TSH) and free thyroxine (FT4) obtained in the second trimester of gestation were analysed and related to iodine intake. Thyroid autoimmunity was also analysed in half of the pregnant women at baseline.

RESULTS

A total of 241 pregnant women were studied. Of these, 56.7% used iodised salt, 46.7% consumed ≥2 servings of dairy products daily and 88.1% took iodine supplements. Median UIC was 191μg/l (135.3-294μg/l), with 68.1% of the women having UIC ≥150μg/l. Only iodised salt consumption provided protection against iodine deficiency (odds ratio 0.35 [0.20-0.63], p=0.001). In women with no autoimmune thyroid disease (n=88), mean levels of TSH were lower in those that consumed iodised salt than in those that did not (respectively, 2.08±0.89mIU/l vs. 2.56±1.02mIU/l, p=0.025). In women with autoimmune thyroid disease (n=30), mean levels of TSH were higher in those that took iodine supplements than in those that did not (respectively, 2.97±1.25mIU/l vs. 1.16±0.41mIU/l, p=0.002).

CONCLUSIONS

The pregnant women studied from Health Area IV in Asturias maintain adequate nutritional iodine status in the second trimester of gestation. In our sample, only the consumption of iodised salt was associated with adequate iodine nutrition, without affecting maternal thyroid function. Most of the women used iodine supplements, which was linked to higher levels of TSH in pregnant women with autoimmune thyroid disease.

A Narrative Review on the Effect of Maternal Hypothyroidism on Fetal Development

The thyroid is a butterfly-shaped gland located in the human body's neck region. The thyroid produces three hormones that are essential for regulating body temperature, energy production, weight, hair and nail growth, and menstrual cycle maintenance. The production of these hormones is controlled by a feedback mechanism. Various factors cause changes in the stimulation and inhibition of these hormones, which ultimately causes either excessive release or a decrease in the levels of thyroid hormones. These causes can be physiological or pathological. One of the physiological causes is pregnancy. Pregnancy is a very complex process in which many changes occur in the body and its functioning. One of which is changes in the maternal thyroid gland. The inability to adequately adapt to the changes leads to the abnormal functioning of the thyroid gland. During pregnancy, there is a variation in the concentration of thyroid hormones which may cause a decrease in levels or inhibition in the production of thyroid hormones. This condition is called hypothyroidism. Hypothyroidism in pregnant mothers can either be gestational or may be a condition that is present way before her pregnancy. Often, gestational hypothyroidism reverts after delivery during the postpartum period but can also be present as subclinical hypothyroidism. In such cases, they pose a significant threat to development, cause growth hindrance to the infant in the womb, and cause abnormalities in the offspring in the future. Some of the changes occur in the gland because of enhancement in levels of thyroid binding globulin, increased clearance rate of iodine from the body in kidneys, altered effects in human chorionic gonadotropin hormone, and decreased consumption of iodine in meals. Iodine disbalance in maternal hypothyroidism is associated with severe health issues like cretinism and mental retardation. Thyroid hormones are crucial for the infant's neural, cognitive, and intelligence quotient development in the womb. Thus, the disturbances in the maternal hormone levels disturb typical early developmental characteristics. In the world of rapidly advancing scientific research, there are many ways in which this condition can be detected early, diagnosed correctly, and given apt and required attention and treatment for causing the least harm to the fetus and the mother.

Correlation Between Hypothyroidism During Pregnancy and Glucose and Lipid Metabolism in Pregnant Women and Its Influence on Pregnancy Outcome and Fetal Growth and Development

Purpose:

To observe the correlation between hypothyroidism during pregnancy and glucose and lipid metabolism in pregnant women and its influence on a pregnancy outcome and fetal growth and development.

Methods

About 152 patients with hypothyroidism during pregnancy in our hospital from June 2017 to June 2020 were selected as the observation group and divided into the overt hypothyroidism (OH) group, the subclinical hypothyroidism (SCH) group, and the low T4 group. Another 60 pregnant women with normal antenatal examination and normal thyroid function were selected as the normal group. The glucose and lipid metabolism indexes of each group were compared. The pregnant women in the OH group and the SCH group were given levothyroxine intervention, and the pregnancy outcome and infant development of the two groups were compared.

Results

The fasting blood glucose and hemoglobin A1c, triglyceride and low-density lipoprotein of the OH group and the SCH group were higher than the low T4 group and the normal group, and the OH group was higher than the SCH group (p < 0.05). The incidence of premature delivery and premature rupture of membranes at term (PROM at term) in the hypothyroidism non-control group was higher than the hypothyroidism control group (p < 0.05). The mental development index and the psychomotor development index in the hypothyroidism non-control group were lower than the hypothyroidism control group (p < 0.05).

Conclusion

Pregnant women with hypothyroidism during pregnancy are more prone to glucose and lipid metabolism disorder, which increases the risk of premature delivery and PROM at term, and has certain influence on the intellectual development and psychomotor development of infants.

Neonatal outcomes and congenital anomalies in pregnancies affected by hypothyroidism

BACKGROUND

Maternal hypothyroidism has been reported to have concerns over neonatal outcomes, not only in the context of neurocognitive development but also in the short term as birth weight and neonatal jaundice.

PATIENTS AND METHODS

We conducted a cross-sectional retrospective study on 638 cases who delivered live births in the Aga Khan University Hospital after ethical approval. Data were collected on hypothyroid pregnant females who were diagnosed before conception or during their antenatal visits during the year 2008-2016. Neonatal outcomes were noted for birth weight, maturity, and neonatal jaundice, neonatal hypothyroidism, neonatal respiratory distress syndrome, sepsis, hypocalcaemia, congenital anomalies, need for intensive care admission, and neonatal death. Subgroup analysis was performed on the timing of diagnosis of maternal hypothyroidism. Data analysis was performed on Statistical Package for the Social Sciences version 20.0.

RESULTS

Neonatal jaundice was the most common neonatal outcome (37.6%) in our cohort of 662 live births. Nearly 15% required intensive care unit admission, however, neonatal death was very rare. The most common clinically significant congenital anomalies were cardiovascular defects, whereas Mongolian spots were the commonest congenital condition to report. There is a statistically significant association between low birth weight (OR 1.86, 95% CI 1.0-3.2, p ≤ 0.05) and congenital anomalies (OR 2.39, 95% CI 1.4-4.0, p ≤ 0.05) with women diagnosed with hypothyroidism before pregnancy.

CONCLUSION

We report the neonatal outcomes and spectrum of congenital anomalies of hypothyroid pregnancies diagnosed before and during conception for the first time from the region of Pakistan.KEY MESSAGEOverall, none of the neonates of hypothyroid pregnancies developed congenital hypothyroidism.Cardiovascular defects in these neonates imply extensive screening and monitoring during pregnancy.Low birth weight and congenital anomalies are associated with the timings of diagnosis of hypothyroidism in pregnancy.

Nutritional Iodine Status in Pregnant Women from Health Area IV in Asturias (Spain): Iodised Salt Is Enough

Background: Iodine deficiency during pregnancy may have adverse effects on the neurodevelopment of the foetus. Recent studies of pregnant women in Asturias (Spain) indicate that nutritional iodine levels are sufficient. The objective of this study was to confirm the appropriate nutritional iodine status and to analyse the influence of the ingestion of iodine on maternal urinary iodine concentration (UIC) and thyroid function. Methods: An observational study was carried out between May and June 2017 on women in the first trimester of pregnancy from Health Area IV in Asturias. The women completed a questionnaire related to their consumption of iodine and samples were taken to analyse UIC and thyroid function. Results: Three hundred and eighteen pregnant women were involved. Of these, 51.10% used iodised salt, 48.90% consumed ≥ 2 servings of dairy products daily and 87.08% took iodine supplements. The median UIC was 171.5 μg/L (116–265 μg/L) and 60.41% of women had UIC ≥ 150 μg/L. Multivariate logistic regression analysis demonstrated that iodised salt had a protective effect on UIC < 150 μg/L (odds ratio (OR) 0.404 (0.237–0.683), p = 0.001), but not iodine supplements (OR 0.512 (0.240–1.085), p = 0.080). The average level of thyroid stimulating hormone (TSH) was 2.26 ± 0.94 mIU/L; 68.40% of pregnant women taking iodine supplements had TSH < 2.5 mIU/L compared to 30.00% of those who were not taking supplements (p = 0.031). Conclusions: The pregnant women in our health area are maintaining appropriate nutritional iodine levels. The consumption of iodised salt protects against iodine deficiency; thus, iodine supplements should be taken on an individualised basis.

1H-NMR based metabolomic profiling of cord blood in gestational hypothyroidism

Background

Gestational hypothyroidism (GHT) is a common pregnancy-related thyroid disfunction. The adverse outcomes by GHT has been increasingly recognized, leading to more public awareness of the disease. However, comprehensive understanding of the prognosis of GHT has not yet achieved. Metabolomics is a powerful tool in evaluation of disease outcomes, and cord blood represents an excellent candidate for the investigation of gestational outcomes.

Methods

In the present study, we performed 1H-NMR based metabolomics on cord blood of 18 pregnant women with GHT and 18 non hypothyroidism (NHT) control.

Results

The metabolomic profile of GHT was separated with the NHT control. A total of 8 metabolites with altered abundances were observed, among which Creatinine and O-Phosphocholine were elevated and the others were downregulated in GHT. Spearman rank correlation suggested that the eight differential metabolites were correlated with the GHT related thyroid hormones. Pathway analysis of the differential metabolites indicated that two metabolic pathways were significantly altered in GHT (adjusted P<0.05), including tyrosine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis. Enrichment analysis of the differential metabolites against disease-associated metabolite sets suggested that GHT was associated with disease risks of non-insulin dependent diabetes mellitus, isovaleric acidemia, and methylmalonic aciduria.

Conclusions

The results of this study revealed GHT associated metabolic changes in cord blood, providing insights into the metabolic intermediates between GHT and its related disease risks.