Can Pretreatment Serum Beta-hCG be Used for Predicting Thyrotoxicosis in Gestational Trophoblastic Disease?

Gestational trophoblastic disease (GTD) comprises a diverse spectrum of entities of abnormal cellular proliferations originating in placental trophoblasts. The specific marker of GTD is beta-hCG which has a similar structure to the TSH molecule, interfering level of thyroid hormones. How and when to check for thyroid function test during this period remain challenging.

To assess values of pretreatment beta-hCG and its benefit for predicting thyrotoxicosis among patients with diagnoses of GTD.

Retrospective analytical study included all women diagnosed with GTD at Lampang Hospital from January 2010 to May 2020. The patients' pretreatment beta-hCG and thyroid function were collected. Sensitivity and specificity for detecting laboratory hyperthyroidism were reported and classified by pretreatment beta-hCG levels.

Forty-four women with diagnoses of GTD were recruited. The range of pretreatment beta-hCG levels were classified  into 4 groups: beta-hCG > 50,000 IU/ml (group 1), beta-hCG > 100,000 IU/ml (group 2), beta-hCG > 150,000 IU/ml (group 3), beta-hCG > 200,000 IU/ml (group 4). The sensitivity for prediction of high fT4 were 100%, 94.1%, 94.1% and 88.2% in group 1,2,3 and 4, respectively, while the specificity were 12%, 20%, 32% and 44% in group 1,2,3 and 4, respectively.

Pretreatment beta-hCG > 100,000 uIU/ml has the high sensitivity and acceptable specificity for predicting hyperthyroidism. So we don't need to check or wait for thyroid function test in patients who had beta-hCG < 100,000 IU/ml.