them at the start of pregnancy? A3. The absolute additional risk of abnormalities with these drugs is still relatively small around 2–3%. However, the risk of pregnancy loss and other serious complications with uncontrolled hyperthyroidism is 50% or more. Hence the risk‐benefit ratio is very much in favor of continued treatment at the start of pregnancy if your hyperthyroidism has not been under control. We will monitor your thyroid function regularly to ensure you are kept well‐controlled on as low a dose of the drug as possible. In many cases the drug can be gradually tailed off and stopped later in pregnancy.
4 Q4 Why do I need my thyroid function checked so often during pregnancy? A4. There are a lot of hormonal changes occurring as your pregnancy progresses. The largest changes occur in the first half of pregnancy. These changes influence your thyroid condition and also alter the requirements for your thyroid treatment. Regular testing ensures that your thyroid function is optimal so that pregnancy complications and harms to your baby can be minimized.
References
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2 2 Lazarus JH, Brown RS, Daumerie C, Hubalewska‐Dydejczyk A, Negro R, Vaidya B. 2014 European Thyroid Association Guidelines for the Management of Subclinical Hypothyroidism in Pregnancy and in Children. Eur Thyroid J. 2014; 3(2):76–94.
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10 10 Casey BM, Thom EA, Peaceman AM, Varner MW, Sorokin Y, Hirtz DG, Reddy UM, Wapner RJ, Thorp JM, Jr., Saade G, Tita AT, Rouse DJ, Sibai B, Iams JD, Mercer BM, Tolosa J, Caritis SN, VanDorsten JP, Eunice Kennedy Shriver National Institute of Child H, Human Development Maternal‐Fetal Medicine Units N. Treatment of Subclinical Hypothyroidism or Hypothyroxinemia in Pregnancy. The New England journal of medicine. 2017; 376(9):815–825.
11 11 Velkeniers B, Van MA, Poppe K, Unuane D, Tournaye H, Haentjens P. Levothyroxine treatment and pregnancy outcome in women with subclinical hypothyroidism undergoing assisted reproduction technologies: systematic review and meta‐analysis of RCTs. HumReprodUpdate. 2013; 19(3):251–258.
12 12 Dhillon‐Smith RK, Middleton LJ, Sunner KK, Cheed V, Baker K, Farrell‐Carver S, Bender‐Atik R, Agrawal R, Bhatia K, Edi‐Osagie E, Ghobara T, Gupta P, Jurkovic D, Khalaf Y, MacLean M, McCabe C, Mulbagal K, Nunes N, Overton C, Quenby S, Rai R, Raine‐Fenning N, Robinson L, Ross J, Sizer A, Small R, Tan A, Underwood M, Kilby MD, Boelaert K, Daniels J, Thangaratinam S, Chan SY, Coomarasamy A. Levothyroxine to increase live births in euthyroid women with thyroid antibodies trying to conceive: the TABLET RCT. Southampton (UK) 2019.
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14 The patient with hyperprolactinemia
John Ayuk
Department of Endocrinology, University Hospitals Birmingham, UK
Case History: A 29‐year‐old woman with a 4‐year history of infertility was referred for IVF treatment. As she had become tearful and depressed, her primary care physician had prescribed an antidepressant. She had no other medical history of note. Menarche was at the age of 14, and her periods had been normal and regular up until 3 years ago, when she developed oligomenorrhea. Blood tests carried out at her first clinic visit showed serum prolactin of 200 μg/L (4000 mIU/L). Her follicle stimulating hormone (FSH), luteinizing hormone (LH) and tubal assessment were normal. A seminal fluid analysis was also normal.
Background
Human prolactin (PRL) is a polypeptide hormone comprising 199 amino acid residues. PRL is predominantly synthesized in and secreted from the lactotroph cells of the anterior pituitary gland under the control of dopamine. 80–90% of serum PRL circulates as the biologically active monomeric PRL, with dimeric and polymeric isoforms, termed macroprolactin, making up the remainder [1,2]. Macroprolactin has decreased biological activity and clearance. The most obvious function of PRL in humans is to support postpartum lactation [2]. During pregnancy, PRL concentration increases up to 10‐fold, and remains elevated during lactation under the stimulus of suckling [3]. PRL blocks the action of LH on the ovary or testis, producing hypogonadism [2]. Hyperprolactinemia inhibits ovulation, resulting in infertility. For this reason, measurement of serum PRL concentration is necessary when investigating ovulatory infertility [4]. Hyperprolactinemia may be asymptomatic, but in women of childbearing age it commonly presents with oligomenorrhea, loss of libido or galactorrhea [5].
Transient rises in PRL levels can occur during the late follicular