Hyperthyroidism during pregnancy: etiology, diagnosis and management

Impending thyroid storm in a pregnant woman with undiagnosed hyperthyroidism: A case report and literature review

RATIONALE

Thyroid storm is a rare complication during caesarean section of patients with hyperthyroidism. It occurs abruptly, with a high mortality rate if not recognized immediately and aggressively treated. Herein, we reported a case of impending thyroid storm during a caesarean section.

PATIENT CONCERNS

A healthy 23-year-old woman with undiagnosed hyperthyroidism underwent an emergency caesarean section under general anesthesia. After tracheal extubation, the patient exhibited abnormal tachycardia, agitation, sweating, and hyperpyrexia.

DIAGNOSES

The clinical manifestation and the following thyroid function test indicate a high index of suspicion for impending thyroid storm.

INTERVENTIONS

Hydrocortisone and esmolol were intravenously administered immediately. Propylthiouracil and propranolol were orally administered after the patient regained complete consciousness.

OUTCOMES

Due to our immediate recognition and aggressive treatment, more serious manifestations of thyroid storm were avoided.

LESSONS

Good antenatal care is very important for pregnant women, and they should be generally screened for thyroid disorders, especially if the resting heart rate is >100 beats/min and weight increases are inconsistent with gestational age. When hyperthyroidism is suspected, drugs that excite the sympathetic nerves or promote the release of histamine should not be used during caesarean section.

Is the measurement of inferior thyroid artery blood flow velocity by color-flow Doppler ultrasonography useful for differential diagnosis between gestational transient thyrotoxicosis and Graves' disease? A prospective study

OBJECTIVE

To determine the role of peak systolic velocity, end-diastolic velocity and resistance indices of both the right and left inferior thyroid arteries measured by color-flow Doppler ultrasonography for a differential diagnosis between gestational transient thyrotoxicosis and Graves' disease during pregnancy.

METHODS

The right and left inferior thyroid artery-peak systolic velocity, end-diastolic velocity and resistance indices of 96 patients with thyrotoxicosis (41 with gestational transient thyrotoxicosis, 31 age-matched pregnant patients with Graves' disease and 24 age- and sex-matched non-pregnant patients with Graves' disease) and 25 age and sex-matched healthy euthyroid subjects were assessed with color-flow Doppler ultrasonography.

RESULTS

The right and left inferior thyroid artery-peak systolic and end-diastolic velocities in patients with gestational transient thyrotoxicosis were found to be significantly lower than those of pregnant patients with Graves' disease and higher than those of healthy euthyroid subjects. However, the right and left inferior thyroid artery peak systolic and end-diastolic velocities in pregnant patients with Graves' disease were significantly lower than those of non-pregnant patients with Graves' disease. The right and left inferior thyroid artery peak systolic and end-diastolic velocities were positively correlated with TSH-receptor antibody levels. We found an overlap between the inferior thyroid artery-blood flow velocities in a considerable number of patients with gestational transient thyrotoxicosis and pregnant patients with Graves' disease.

CONCLUSIONS

This study suggests that the measurement of inferior thyroid artery-blood flow velocities with color-flow Doppler ultrasonography does not have sufficient sensitivity and specificity to be recommended as an initial diagnostic test for a differential diagnosis between gestational transient thyrotoxicosis and Graves' disease during pregnancy.

Hyperthyroidism and pregnancy

Pregnant women with hyperthyroidism need careful management as some may be at increased risk of fetal loss, pre-eclampsia, heart failure, premature labour, and having a low birthweight baby

Significance of low thyroid-stimulating hormone in pregnancy

PURPOSE OF REVIEW

To describe the significance of low thyroid-stimulating hormone in pregnancy.

RECENT FINDINGS

Interpretation of thyroid function in pregnancy must be seen in the context of changes in thyroid economy associated with gestation. Improvements in thyroid-stimulating hormone assay methodology have resulted in accurate identification of low and suppressed thyroid-stimulating hormone in pregnancy, and recent studies of screening thyroid function in pregnancy have found an incidence of low thyroid-stimulating hormone in up to 18% of women. Normative gestational-related reference ranges for thyroid hormones, particularly thyroid-stimulating hormone and thyroxine, should be established to identify the higher as well as the lower limits of these analytes. The adverse obstetric and neonatal outcomes associated with hyperthyroidism due to Graves' disease mean that this must be differentiated from the more common cause of suppressed thyroid-stimulating hormone, i.e. gestational transient thyrotoxicosis. It is suggested that estimation of thyroid peroxidase antibodies may be a useful initial diagnostic strategy in the evaluation of women with a low or suppressed thyroid-stimulating hormone.

SUMMARY

In addition to identifying women with high thyroid-stimulating hormone levels at screening (with implications for child intelligence), establishing the cause of low thyroid-stimulating hormone will improve obstetric outcome in a number of pregnant women.