Search

Background: Prompt intervention can prevent permanent adverse neurological effects caused by neonatal hypothyroidism. Thyroid function changes rapidly in the first few days of life but well-defined age-specific reference intervals (RIs) for thyroid-stimulating hormone (TSH), free thyroxine (FT4) and free tri-iodothyronine (FT3) are not available to aid interpretation. We developed hour-based RIs using data mining., Methods: All TSH, FT4 and FT3 results with date and time of collection from neonates aged <7 days during 2005-2015 were extracted from the Monash Pathology database. Neonates with more than one episode of testing or with known primary hypothyroidism, identified by treating physicians or from medical records, were excluded from the analysis. The date and time of birth were obtained from the medical records., Results: Of the 728 neonates qualifying for the study, 569 had time of birth available. All 569 had TSH, 415 had FT4 and 146 had FT3 results. For age ≤24 h, 25-48 h, 49-72 h, 73-96 h, 97-120 h, 121-144 h and 145-168 h of life, the TSH RIs (2.5th-97.5th) (mIU/L) were 4.1-40.2, 3.2-29.6, 2.6-17.3, 2.2-14.7, 1.8-14.2, 1.4-12.7 and 1.0-8.3, respectively; the FT4 RIs (mean ± 2 standard deviation [SD]) (pmol/L) were 15.3-43.6, 14.7-53.2, 16.5-45.5, 17.8-39.4, 15.3-32.1, 14.5-32.6 and 13.9-30.9, respectively; the FT3 RIs (mean±2 SD) (pmol/L) were 5.0-9.4, 4.1-9.1, 2.8-7.8, 2.9-7.8, 3.5-7.2, 3.4-8.0 and 3.8-7.9, respectively., Conclusions: TSH and FT4 were substantially high in the first 24 h after birth followed by a rapid decline over the subsequent 168 h. Use of hour-based RIs in newborns allows for more accurate identification of neonates who are at risk of hypothyroidism.

Maternal Graves' disease can cause neonatal hypo- and hyperthyroidism in the affected neonate. Thyroid function tests (TFTs) in the first 48 h were initially consistent with central hypothyroidism, followed within 2 weeks by symptomatic hyperthyroidism due to maternal antibodies (neonatal GD). [Extracted from the article]

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. [ABSTRACT FROM AUTHOR]

The article presents information on a study aimed at establishing reference intervals (RIs) for thyroid stimulating hormone (TSH), free thyroxine (fT4). It also aimed to track intraindividual changes in thyroid function during pregnancy in 130 women without antithyroid peroxidase antibodies. It has been concluded that the use of trimester-specific RIs would prevent thyroid function misclassification during pregnancy.

A letter to the editor is presented in response to the article "Interference by biotin therapy on measurement of thyroid-stimulating hormone (TSH) and free thyroxine 4 (FT4) by enzyme immunoassay on Boehringer Mannheim ES700 analyser," by J. G. Henry, S. Sobki and N. Arafat in a previous journal issue.