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Thyrotoxicosis and hyperemesis gravidarum associated with a serum activity which stimulates human thyroid cells in
R L Kennedy1, J Darne, R Davies
1Department of Medicine, Northern General Hospital, Sheffield, UK.
Objective:
To investigate in-vitro thyroid stimulatory activity in the serum of patients with hyperemesis gravidarum and thyrotoxicosis.
Design:
Serum from hyperthyroid patients was incubated with cultures of human thyroid cells. Attempts were made to neutralize stimulatory activity with antisera to hCG.
Patients:
Five patients presenting in early pregnancy with hyperemesis and thyrotoxicosis.
Measurements:
Serum concentrations of thyroid hormones (total and free), TSH and hCG. Accumulation of extracellular cAMP in response to serum.
Results:
All five patients had biochemical hyperthyroidism with no evidence of an underlying autoimmune disease. The mean cAMP accumulation over 4 hours with sera from 12 non-pregnant controls was 130.6 (121.8-142.8), from 12 pregnant controls 132.4 (118.1-143.8), compared with values of 144.7, 159.1, 166.2, 178.9 and 320.5 for the thyrotoxic patients. The stimulatory activity could not be neutralized by addition of anti-hCG or by depleting the sera of hCG.
Conclusions:
Thyrotoxicosis may present with hyperemesis in early pregnancy. Clinical and biochemical features may be masked by the pregnancy or by the intercurrent illness. The hypothesis that hCG is a thyroid stimulator in patients with hyperemesis gravidarum is not supported by the immuno-neutralization data in this study.