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Introduction: UK screening for congenital hypothyroidism (CH) is based on dried blood spot Thyroid Stimulating Hormone (TSH). Scintigraphy may identify CH subtypes classified as dysplasia, gland in situ (GIS) and ectopia, but is not performed in all centres. We retrospectively investigated the role of scintigraphy to identify CH subtypes in a single tertiary centre cohort.Methods: Babies who screened positive for CH between 2007 and 2017 were studied (n=418 of 534 783). Scintigraphy outcomes were correlated with TSH and levothyroxine dose. GIS patients were analysed for 3-year outcomes.Results: 303 patients started levothyroxine. Scintigraphy demonstrated three subtypes: GIS (n=139, 46%) ectopia (n=84, 28%) and dysplasia (n=80, 26%). Three-year follow up demonstrated permanence in 54% of 37 GIS cases.Discussion: Thyroid scintigraphy differentiates subtypes of CH and suggests a higher than expected proportion of patients with GIS and ectopia. CH is permanent in half of those with GIS. [ABSTRACT FROM AUTHOR]

Background: A subnormal cortisol response (30 min level (C30min)<550 nmol/L) to synthetic adrenocorticotrophic hormone/Synacthen test (SDST) in all infants does not necessarily indicate underlying or persistent hypothalamic-pituitary-adrenal axis pathology.Methods: We retrospectively evaluated the diagnoses and outcomes in 68 infants who had a SDST at age <6 months from 2011 to 2014.Results: 29 (43%) infants had a subnormal SDST. Causative pathology was identified in 9/29 (31%). In 20/29 (69%) with no identified pathology, repeat SDST was normal in 18/20 (90%) at median age 0.6 (range 0.1-3.2) years but persistently subnormal in 2. Those with a transient abnormality were more likely to be small for gestational age (P=0.03) and had higher initial SDST C30min (390 nmol/L vs 181 nmol/L, P=0.01) than those with pathology.Conclusion: Specific aetiology can be identified in a third of infants with a subnormal SDST. When the aetiology remains elusive, adrenal function should be reassessed as the problem can be transient. [ABSTRACT FROM AUTHOR]

A thyroid function test (TFT) is a common investigation, often undertaken by general paediatricians and general practitioners. TFT involves the measurement of serum free thyroxine (fT4) and thyroid stimulating hormone (TSH) to guide the diagnosis and management of hypothyroidism and hyperthyroidism, requiring treatment with medications such as levothyroxine (LT4) and carbimazole. Thyroid hormones play a crucial role in early life neurodevelopment; therefore, the correct interpretation of TFT is required to optimise treatment outcomes. TFT needs to be contextualised to influencing factors such as intercurrent illness, diet, presence of obesity, assay interference and non-adherence to treatment., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

In 2015, U.K. newborn screening (NBS) laboratory guidelines were introduced to standardize dried blood spot (DBS) specimen quality acceptance and specify a minimum acceptable DBS diameter of ≥7 mm. The UK 'acceptable' avoidable repeat rate (AVRR) is ≤2%. To assess inter-laboratory variability in specimen acceptance/rejection, two sets of colored scanned images ( n = 40/set) of both good and poor-quality DBS specimens were distributed to all 16 U.K. NBS laboratories for evaluation as part of an external quality assurance (EQA) assessment. The mean (range) number of specimens rejected in the first EQA distribution was 7 (1-16) and in the second EQA distribution was 7 (0-16), demonstrating that adherence to the 2015 guidelines was highly variable. A new minimum standard for DBS size of ≥8 mm (to enable a minimum of six sub-punches from two DBS) was discussed. NBS laboratories undertook a prospective audit and demonstrated that using ≥8 mm as the minimum acceptable DBS diameter would increase the AVRR from 2.1% (range 0.55% to 5.5%) to 7.8% (range 0.55% to 22.7%). A significant inverse association between the number of specimens rejected in the DBS EQA distributions and the predicted AVVR (using ≥8 mm minimum standard) was observed (r = -0.734, p = 0.003). Before implementing more stringent standards, the impact of a standard operating procedure (SOP) designed to enable a standardized approach of visual assessment and using the existing ≥7 mm diameter (to enable a minimum of four sub-punches from two DBS) as the minimum standard was assessed in a retrospective audit. Implementation of the SOP and using the ≥7 mm DBS diameter would increase the AVRR from 2.3% (range 0.63% to 5.3%) to 6.5% (range 4.3% to 20.9%). The results demonstrate that there is inconsistency in applying the acceptance/rejection criteria, and that a low AVVR is not an indication of good-quality specimens being received into laboratories. Further work is underway to introduce and maintain standards without increasing the AVRR to unacceptable levels.