Prevalence and aetiology of thyrotoxicosis in patients with hyperemesis gravidarum presenting to a tertiary hospital in Cape Town, South Africa
Date
2021-08-31
Journal Title
Journal ISSN
Volume Title
Publisher
AJOL
Abstract
Background: The association between hyperemesis gravidarum (HG) and abnormal thyroid function is well known.
Aims: The prevalence, aetiology and course of thyrotoxicosis in women with hyperemesis gravidarum (HG) were studied.
Methods: Women admitted for HG, who underwent thyroid function evaluation between 1 August 2016 and 30 April 2019,
were studied. Laboratory data included baseline human chorionic gonadotropin (hCG) and baseline (t1), discharge (t2) and
follow-up (t3) thyroid function tests (thyroid stimulating hormone [TSH] and free thyroxin [fT4]). Available TSH receptor
antibody status was assessed.
Results: Eighty-two patients were included. The incidence of thyrotoxicosis was 49% based on local laboratory TSH range and
48% if trimester-specific ranges used. In the majority of normal pregnancies, thyrotoxicosis was hCG-mediated (72.5%), 15%
were confirmed to have Graves’ disease and 12% had a molar pregnancy. Very high fT4 levels (> 40 pmol/l) at baseline [t1]
were documented in 24% of women with hCG-mediated thyrotoxicosis. Clinical features were absent in a third of women
with Graves’ disease and the diagnosis was reliant on positive antibody status. Free T4 values declined from (t1) to later in
gestation (t3) (p < 0.001).
Conclusion: The incidence of thyrotoxicosis in women with HG is high. Free-T4 values decrease with clinical stabilisation of HG,
suggesting a contribution of dehydration to the large variation in baseline fT4 measurements. Testing for TSH-receptor
antibodies should be considered in women with TSH < 0.01 pmol/l and persistent fT4 elevation on follow-up. Final review
of thyroid function should be performed after 15 weeks’ gestation.
Description
CITATION: Van der Made, T. et al. 2021. Prevalence and aetiology of thyrotoxicosis in patients with hyperemesis gravidarum presenting to a tertiary hospital in Cape Town, South Africa. Journal of Endocrinology, Metabolism and Diabetes of South Africa 2021; 26(1):1–8. doi.10.1080/16089677.2020.1831740
The original publication is available at: ajol
The original publication is available at: ajol
Keywords
Hyperthyroidism, Graves’ disease, Chorionic gonadotropins, Hyperemesis gravidarum, Hypothalamic-pituitary-thyroid axis