According to recent research published in the journal Thyroid, 'During pregnancy, when human chorionic gonadotropin (hCG) concentrations are highest, there is a transient suppression of serum thyrotropin (TSH). In normal pregnancy, TSH concentrations generally remain within nonpregnant reference intervals; however, in some patients TSH is suppressed.'
'Here we sought to extend previous studies to examine the relationship between very high serum concentrations of hCG (> 200,000 IU/L) and the thyroid hormones TSH and free thyroxine (FT4). The objective of this study was to determine: 1) if there is an hCG concentration above which TSH concentrations are suppressed (<= 0.2 mu IU/mL); 2) how thyroid hormone concentrations change in response to changes in hCG concentrations; and 3) the clinical symptoms in patients with such extremely elevated hCG concentrations. Residual specimens sent to the laboratories for physician-ordered hCG testing were utilized. Over 26 months, 15,597 physician-ordered hCG tests were performed. Sixty-nine specimens from 63 women with hCG concentrations > 200,000 IU/L were identified, and TSH and FT4 concentrations were measured. Medical records were reviewed for clinical information. Thirty-seven percent of subjects had hyperemesis gravidarum (HG) and 19% had gestational trophoblastic disease (GTD). TSH was suppressed (<= 0.2 mu IU/mL) in 67% of the specimens with hCG concentrations > 200,000 IU/L and 100% of specimens with hCG concentrations > 400,000 IU/L. FT4 concentrations were elevated above the reference interval (1.8 ng/dL) in 32% of specimens with hCG concentrations > 200,000 IU/L and in 80% of specimens with hCG concentrations > 400,000 IU/L. Only four subjects had documented signs of hyperthyroidism. Women with GTD had a median hCG concentration twofold higher than women with HG and a median TSH concentration one half that of women with HG,' wrote C.M. Lockwood and colleagues, Washington University, Medical Department (see also Women's Health).
The researchers concluded: '1) At hCG concentrations > 400,000 IU/L, TSH is consistently suppressed; 2) serum FT4 and TSH respond to changes in serum hCG concentrations; and 3) most patients with hCG concentrations > 200,000 IU/L lack overt hyperthyroid symptoms.'
Lockwood and colleagues published their study in Thyroid (Serum Human Chorionic Gonadotropin Concentrations Greater than 400,000 IU/L Are Invariably Associated with Suppressed Serum Thyrotropin Concentrations. Thyroid, 2009;19(8):863-868).
For additional information, contact A.M. Gronowski, Washington University, School Medical, Dept. of Pathology & Immunology, 660 S Euclid, Box 8118, St. Louis, MO 63110, USA.
The publisher's contact information for the journal Thyroid is: Mary Ann Liebert Inc., 140 Huguenot Street, 3RD FL, New Rochelle, NY 10801, USA.
Keywords: United States, Box, Women's Health, Chorionic, Chorionic Gonadotropin, Drugs, Gonadotropin, Hormones, Obstetrics, Pharmaceuticals, Pregnancy, Therapy, Thyrotropin, Treatment, Washington University, Medical Department.
This article was prepared by Women's Health Weekly editors from staff and other reports. Copyright 2009, Women's Health Weekly via NewsRx.com.
