Subclinical hypothyroidism during pregnancy: the Melbourne public hospitals consensus

Peter S Hamblin; Penelope M Sheehan; Carolyn Allan; Christine A Houlihan; Zhong X Lu; Simon P Forehan; Duncan J Topliss; Christopher Gilfillan; Bala Krishnamurthy; Debra Renouf; Shoshana Sztal-Mazer; Suresh Varadarajan

doi:10.1111/imj.14210

Subclinical hypothyroidism during pregnancy: the Melbourne public hospitals consensus

Intern Med J. 2019 Aug;49(8):994-1000. doi: 10.1111/imj.14210.

Authors

Peter S Hamblin^{1

2}, Penelope M Sheehan^{3

4}, Carolyn Allan^{5

6}, Christine A Houlihan^{7

8}, Zhong X Lu^{9

10}, Simon P Forehan¹¹, Duncan J Topliss^{12

13}, Christopher Gilfillan^{14

15}, Bala Krishnamurthy^{16

17}, Debra Renouf^{18

19}, Shoshana Sztal-Mazer^{12

13}, Suresh Varadarajan²⁰

Affiliations

¹ Department of Endocrinology and Diabetes, Western Health, Sunshine Hospital, Melbourne, Victoria, Australia.
² Department of Medicine - Western Precinct, The University of Melbourne, Melbourne, Victoria, Australia.
³ Pregnancy Research Centre, Royal Women's Hospital, Melbourne, Victoria, Australia.
⁴ Department of Obstetrics and Gynaecology, Royal Women's Hospital, University of Melbourne, Melbourne, Victoria, Australia.
⁵ Endocrine Services in Pregnancy, Monash Health, Melbourne, Victoria, Australia.
⁶ Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research, Melbourne, Victoria, Australia.
⁷ Diabetes and Endocrine Clinic, Mercy Hospital for Women, Melbourne, Victoria, Australia.
⁸ Department of Endocrinology and Diabetes, Austin Health, Melbourne, Victoria, Australia.
⁹ Department of Chemical Pathology, Melbourne Pathology, Melbourne, Victoria, Australia.
¹⁰ Department of Medicine, and, Monash University, Melbourne, Victoria, Australia.
¹¹ Department of Diabetes and Endocrinology, Royal Melbourne Hospital, Melbourne, Victoria, Australia.
¹² Department of Endocrinology and Diabetes, The Alfred, Melbourne, Victoria, Australia.
¹³ Department of Medicine, Central Clinical School, Monash University, The Alfred, Melbourne, Victoria, Australia.
¹⁴ Department of Endocrinology and Diabetes, Eastern Health, Melbourne, Victoria, Australia.
¹⁵ Department of Medicine, Eastern Clinical School, Monash University, Melbourne, Victoria, Australia.
¹⁶ Department of Endocrinology, Werribee Mercy Hospital, Melbourne, Victoria, Australia.
¹⁷ St Vincent's Institute of Medical Research, St Vincent's Hospital, Melbourne, Victoria, Australia.
¹⁸ Department of Endocrinology and Diabetes, Peninsula Health, Melbourne, Victoria, Australia.
¹⁹ Peninsula Clinical School, Monash University, Melbourne, Victoria, Australia.
²⁰ Department of Endocrinology and Diabetes, Northern Health, Melbourne, Victoria, Australia.

PMID: 30561039
DOI: 10.1111/imj.14210

Abstract

Background: Interest in potential adverse outcomes associated with maternal subclinical hypothyroidism (normal free T4, elevated thyroid-stimulating hormone (TSH)) has increased significantly over recent years. In turn, the frequency of maternal thyroid function testing has risen, despite universal thyroid function screening not being recommended, leading to a marked increase in referrals to obstetric endocrinology clinics. In 2017 the American Thyroid Association revised their diagnostic and management guidelines. Although welcome, these new guidelines contain recommendations that may cause confusion in clinical practice.

Aim: To ensure uniform practice in the diagnosis and management of subclinical hypothyroidism in pregnancy across all Melbourne public hospitals.

Methods: Endocrinology and obstetric representatives from all Melbourne public hospital networks reviewed the 2017 American Thyroid Association guidelines and other relevant literature to develop a consensus for diagnosing and treating subclinical hypothyroidism during pregnancy in Melbourne. The consensus guidelines were then referred to the Endocrine Society of Australia for comment and endorsement.

Results: Consensus was achieved and the guidelines were endorsed by the Council of the Endocrine Society of Australia. Trimester and assay-specific TSH reference intervals derived from healthy local populations should be used, where available. When unavailable, a TSH cut-off of 4 mU/L (replacing the previously recommended 2.5 mU/L) should be used to initiate treatment, irrespective of thyroid auto-antibody status. The recommended starting dose of levothyroxine is 50 μg daily, with a therapeutic TSH target of 0.1-2.5 mU/L. Levothyroxine should generally be ceased after delivery, with some exceptions. Hospitals will ensure smooth transfer of care back to the woman's general practitioner with clear documentation of pregnancy thyroid management and a recommended plan for follow-up.

Conclusion: Fewer women will be classified as having subclinical hypothyroidism during pregnancy, which is likely to lead to reductions in emotional stress, hospital visits, repeated blood tests and financial costs. Uniform clinical practice will occur across Melbourne.

Keywords: hypothyroidism; pregnancy; subclinical hypothyroidism.

MeSH terms

Adult
Australia
Consensus
Female
Hospitals, Public
Humans
Hypothyroidism / blood
Hypothyroidism / diagnosis*
Hypothyroidism / drug therapy*
Practice Guidelines as Topic
Pregnancy
Pregnancy Complications / blood
Pregnancy Complications / diagnosis*
Pregnancy Complications / drug therapy*
Reference Values
Thyroid Function Tests
Thyroxine / administration & dosage*

Substances

Thyroxine