Thyroid function in patients with hyperemesis gravidarum

Area of Science:

• Endocrinology
• Maternal-Fetal Medicine
• Obstetrics

Background:

• Hyperemesis gravidarum is a severe pregnancy complication characterized by intense nausea and vomiting.
• Thyroid function abnormalities can occur during pregnancy, necessitating careful differential diagnosis.

Purpose of the Study:

• To investigate thyroid function, specifically free thyroxine (T4) and free triiodothyronine (T3) indices, in pregnancies complicated by severe hyperemesis gravidarum.
• To determine the relationship between thyroid function abnormalities and pregnancy outcomes, including abortion rates, pregnancy duration, and birth weight.

Main Methods:

• Studied 33 consecutive pregnancies with severe hyperemesis gravidarum.
• Measured free thyroxine (T4) and free triiodothyronine (T3) indices.
• Assessed thyrotropin response to thyrotropin-releasing hormone (TRH) in a subset of patients.

Main Results:

• Elevated free T4 index was observed in 73% of patients; elevated free T3 index was less common.
• No significant thyrotropin response to TRH was noted in tested patients, and classic hyperthyroid signs were absent.
• Thyroxinemia resolved spontaneously within weeks, irrespective of antithyroid drug treatment, and did not impact abortion rates or pregnancy duration, but was associated with lower birth weight.

Conclusions:

• Severe hyperemesis gravidarum is frequently associated with elevated free T4 index, mimicking hyperthyroidism.
• This condition should be considered in the differential diagnosis of thyrotoxicosis during pregnancy.
• While not directly impacting pregnancy loss or duration, maternal thyroxinemia may be linked to reduced fetal growth.