Hyperthyroidism During Pregnancy: A Clinical Approach

Thyroid storm in pregnancy: a review

BACKGROUND

Thyroid storm is a state of circulating thyroid hormone excess leading to multiorgan dysfunction and systemic decompensation. It typically occurs in the setting of poorly controlled hyperthyroidism and a precipitating illness or event. Management of thyroid storm in pregnancy poses unique diagnostic and therapeutic challenges.

MAIN BODY

Thyroid storm is a clinical diagnosis characterized by hyperpyrexia, tachyarrhythmias, congestive heart failure, gastrointestinal and neuropsychiatric disturbances. However, diagnostic scoring systems have not been validated in pregnancy. Treatment involves specialist consultation, supportive care, and pharmacological options such as anti-thyroid medications, beta blockers, iodine solutions, glucocorticoids, and cholestyramine. These must be adapted and modified in pregnancy to prevent fetal and maternal complications.

CONCLUSION

There is a critical need to recognize thyroid storm during pregnancy and initiate proper medical interventions promptly.

Analysis of Subclinical Thyroid Dysfunction and Metabolic Abnormality in 28568 Healthy People

We analyzed the detection rates of metabolic syndrome (MetS) and subclinical thyroid dysfunction, including subclinical hyperthyroidism (SCHyper) and subclinical hypothyroidism (SCH), in healthy people, as well as their relationship. Clinical data were collected from 28,568 healthy individuals who underwent physical examinations. The detection rates of SCHyper, SCH, and MetS, as well as in different genders and ages, were analyzed. The detection rate of SCHyper and SCH in females was significantly higher than that in males (P < 0.001), but that of MetS in males was significantly higher than that in females (P < 0.001). In each age group, the detection rate of SCH in females was higher than that in males (P < 0.001). The detection rate of SCH was significantly different in different age groups (P < 0.001). The detection rates of hyperlipidemia (P < 0.001), obesity (P = 0.004), hypertension (P = 0.009), and hyperglycemia (P < 0.001) in the female SCH group were significantly higher than those in the normal group. The detection rates of hyperlipidemia (P = 0.006), obesity (P = 0.04), and hypertension (P = 0.04) in the male SCH group were higher than those in the normal group. The males with SCHyper were more prone to hyperlipidemia (P = 0.02) and obesity (P = 0.03). In addition, the female SCHyper group was not significantly different from the normal group (P > 0.05). Conclusively, the detection rate of SCHyper and SCH in females is higher than that in males, which increases with age. Attention should be paid to subclinical thyroid dysfunction in elderly people, especially females. Early individualized screening and early intervention should be carried out for people with abnormal metabolism.

Effects of Methimazole vs Propylthiouracil in Newborns: A Comparative Review

Hyperthyroidism is more common in women and the sensitivity of thyroid function changes during pregnancy. Excess levels of thyroid hormones and thioamides have a major impact on maternal and fetal outcomes. Our aim was to perform an extensive literature review and provide relevant details concerning the analytical and clinical aspects of the potential effects of the two main drugs used (methimazole and propylthiouracil) in newborns. A thorough literature review was conducted using PubMed and Google Scholar databases. In total, 10 relevant studies were identified and data from these studies were extracted and then extrapolated into results after analysis. Three out of four studies that used methimazole and carbimazole, one and two, respectively, showed adverse fetal outcomes requiring surgical management for congenital anomalies like aplasia cutis, patent vitellointestinal duct, and gastroschisis. Out of the three studies that used propylthiouracil, one baby underwent surgery for bilateral pyelectasis, vesicovaginal fistula, anal stenosis, and polydactyly. The findings of the aforementioned studies provide enough evidence to imply that the use of methimazole and carbimazole to treat antenatal hyperthyroidism has worse fetal outcomes than the use of propylthiouracil. Also, given the paucity of data in the existing literature regarding propylthiouracil's effects on newborns, further studies in this demographic are needed.

Thyroid Storm Caused by Hyperemesis Gravidarum

Background

Transient thyrotoxicosis has been documented in the setting of hyperemesis gravidarum (HG) with elevated human chorionic gonadotropin (hCG) levels. Thyroid storm in pregnancy is rarer and typically associated with autoimmune hyperthyroidism. We described thyroid storm in a primigravid 18-year-old patient due to hCG level elevation secondary to HG, which resolved in the second trimester of pregnancy.

Case Report

Our patient presented with vomiting, hyperthyroidism, and cardiac and renal dysfunction at 16 weeks’ gestation. She was clinically found to have a thyroid storm, with undetectable thyroid-stimulating hormone (TSH) and a free thyroxine level of >6.99 ng/dL. The hCG level was elevated at 246 030 mIU/L (9040-56 451 mIU/L). She was treated with methimazole, saturated solution potassium iodide, and propranolol. Because thyroid autoantibodies were absent, thyroid ultrasound yielded normal results, and thyroid function testing results rapidly improved as the hCG level decreased, the medications were tapered and ultimately discontinued by day 10 of hospitalization. The thyroid function remained normal after discharge.

Discussion

Because hCG and TSH have identical alfa subunits and similar beta subunits, hCG can bind to the TSH receptor and stimulate thyroxine production. The hCG level peaks at around 8-14 weeks of gestation, correlating with decreased TSH levels in this same time frame. This case emphasizes the relevant physiology and importance of timely and thorough evaluation to determine the appropriate management, prognosis, and follow-up for patients with thyroid storm in the setting of HG.

Conclusion

Although transient thyrotoxicosis is documented in patients with HG, thyroid storm is rare, and our case illustrates a severe example of these comorbidities.

Teratogen update: Antithyroid medications

OBJECTIVE

Thyroid disorders including hyperthyroidism are common during pregnancy. Untreated hyperthyroidism can result in adverse outcomes for pregnancy.

METHODS

Iodine, propylthiouracil (PTU), carbimazole (CMZ), and methimazole (MMI) are common medications for hyperthyroidism treatment. The literature regarding antithyroid medication use in pregnancy and breastfeeding is reviewed.

RESULTS

Animal studies for PTU have suggested congenital anomalies while animal studies for MMI have only indicated adverse outcomes at higher doses than used in humans. Epidemiological studies have noted an increased risk of congenital anomalies for PTU less often than CMZ or MMI but the epidemiological evidence remains mixed. A pattern of anomalies has been described for CMZ and MMI, from both case and epidemiological studies, including choanal atresia, aplasia cutis congenita, and other facial, heart, gastrointestinal, and skin anomalies. Closer examination of cases indicates that a few cases of the anomalies have occurred without exposure to CMZ or MMI and outside of the proposed critical period. PTU has a small risk of hepatotoxicity which rarely results in liver transplantation and death. Some authors have suggested that PTU be prescribed in early pregnancy and switched to MMI in late pregnancy. Untreated hyperthyroidism, from either a lack of medications or switching medications during the first trimester, may also increase the chance of congenital anomalies. Multiple case studies and larger epidemiological studies have failed to provide clear, consistent outcomes for the use of PTU, CMZ, and MMI in pregnancy. MMI and PTU both enter the breastmilk in small amounts.

CONCLUSION

Additional research is needed to assist in the medical management and exposure counseling of pregnant and breastfeeding women with hyperthyroidism.