Neonatal TSH as a marker of iodine nutrition status. Effect of maternal ioduria and thyroid function on neonatal TSH

• Published in: Anales de Pediatría 2022-12, Vol.97 (6), p.375-382
• Main Authors: González Martínez, Silvia, Prieto García, Belén, Escudero Gomis, Ana Isabel, Delgado Álvarez, Elías, Menéndez Torre, Edelmiro Luis
• Format: Article
• Language: English
• Subjects: Concentración urinaria de yodo; Female; Función tiroidea; Gestación; Gestation; Gestational weight; Humans; Infant, Newborn; Iodine; Neonatal TSH; Nutritional Status; Peso gestacional; Pregnancy; Prevalence; Thyroid function; Thyroid Gland; Thyrotropin; TSH neonatal; Urinary iodine concentration
• ISSN: 2341-2879; 2341-2879
• DOI: 10.1016/j.anpede.2022.09.008

[Display omitted] Neonatal thyroid stimulating hormone (nTSH) is a marker of iodine nutrition status in the population. The WHO considers a prevalence of less than 3% of nTSH levels greater than 5 mIU/L in samples obtained within 72h from birth indicative of iodine sufficiency. The aim of this study was to determine the prevalence of nTSH levels greater than 5 mIU/L in an iodine-sufficient population and its association with maternal, neonatal and obstetric factors. A total of 243 pregnant women were recruited between May and June 2017 in our health area. A questionnaire of iodine intake was administered, in addition to determination of ioduria, thyroid function and autoimmunity in the first trimester of gestation. We analysed nTSH levels in samples collected between 48 and 72h post birth and other obstetric and neonatal factors. The mean nTSH level (standard deviation) was 2.43 (1.68 mIU/L), with 7.8% of neonates having levels greater than 5 mIU/L. The highest nTSH levels corresponded to neonates of mothers with insufficient ioduria (P = 0.021) or TSH levels greater than 2.5 mIU/L, in both the case of negative (P = 0.049) and positive (P = 0.006) thyroid autoimmunity results. Maternal ioduria less than 150 μg/L was a risk factor for nTSH levels greater than 5 mIU/L (3.70 [1.06−14.60]; P = 0.046), while a neonatal weight of 2500 g or greater was a protective factor (0.14 [0.02−1.00]; P = 0.038). The prevalence of nTSH levels greater than 5 mIU/L in our health area was high based on the WHO recommendations. Maternal iodine deficiency was associated with a higher risk of nTSH levels greater than 5 mIU/L. Given that nTSH is currently measured before 72h post birth, we need new cut-off points to keep on using nTSH as a marker of iodine nutritional status. La TSH neonatal (TSHn) es un marcador de nutrición de yodo en la población. La OMS relaciona una prevalencia 5 mUI/L, obtenidas a partir de las 72h del nacimiento, con un adecuado estado nutricional de yodo. El objetivo de este estudio es conocer la prevalencia de TSHn >5 mUI/L en una población yodosuficiente y su relación con factores maternos, neonatales y obstétricos. Se reclutaron 243 gestantes entre mayo y junio de 2017 en nuestra área sanitaria. Se realizó un cuestionario sobre consumo de yodo y determinación de yoduria, función y autoinmunidad tiroideas en el primer trimestre de gestación. Se analizó la TSHn entre 48−72h del nacimiento, así como otros factores obstétricos y neonatales. La