Format

Send to

Choose Destination
See comment in PubMed Commons below
J Clin Endocrinol Metab. 1988 Apr;66(4):853-6.

Human chorionic gonadotropin (hCG) and thyroid function in early human pregnancy: circadian variation and evidence for intrinsic thyrotropic activity of hCG.

Author information

1
Minerva Foundation Institute for Medical Research, Helsinki, Finland.

Abstract

To explore the diurnal variation and the relationship between serum hCG levels and thyroid function during pregnancy, 26 women with an uncomplicated early pregnancy were studied before and after interruption of pregnancy. The high serum hCG levels in early pregnancy were accompanied by an increase in serum thyroid hormone and a decrease in serum TSH levels. Nevertheless, serum TSH exhibited diurnal variation similar to that in nonpregnant women. The nocturnal surge of TSH exceeded the daytime nadir by 112% and was distinctly different from the normal serum cortisol variation. The diurnal serum T4 and hCG variations were similar to the variation in serum protein concentrations. After pregnancy interruption, serum hCG levels decreased by 95% within 10 days, and TSH levels rose concomitantly from 0.80 to 1.48 mIU/L (P less than 0.001). In individual women serum hCG correlated negatively with TSH (r = 0.322; P = 0.005) and positively with free T3 (r = 0.388; P less than 0.001). These results suggest that hCG has thyrotropic activity, which, through rises in thyroid hormone levels, suppresses TSH secretion. In this regard, 27,000-128,000 IU hCG correspond to 1 mIU TSH. Pregnancy-induced changes in thyroid function, however, do not affect the circadian TSH rhythm.

PMID:
3346361
DOI:
10.1210/jcem-66-4-853
[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Silverchair Information Systems
    Loading ...
    Support Center