Abstract
In 10 patients with GH deficiency and signs of mild hypothyroidism (7x idiopathic, 3x craniopharyngeoma), we found increased basal plasma TSH levels. Diagnosis of GH deficiency was based on absent GH response to insulin and/or arginine without and with T4 therapy, on high HGH induced N-retention and on good growth response to HGH therapy. Primary hypothyroidrsm had been excluded by T4 rise after TRH and/or TSH stimulation and by poor growth response to T4 therapy. TRH(200,ug/m2 i.v.) led to an exaggerated TSH response in the 5 patients tested. This is in contrast to the results in 50 other GH deficient children with (a) normal TSH curves (isolated GH deficiency, n=23), (b) absent TSH response (pituitary hypothyroidism n=8), (c) delayed TSH rise (hypothalamic hypothyroidism, n=19). T4 led to a normalisation of TSH in all but 2 patients with craniopharyngeoma. In these 2, diabetes insipidus was treated with pituitary extracts possibly containing substances crossreacting in our assay system. In the remaining 8 patients, elevated TSH levels were alternating with normal values suggesting a feedback mechanism between thyroid and pituitary gland. We assume that in some patients with hypothalamic disorders, TSH is secreted in a biologically less active form (subunits ?) immunologically crossreacting with normal TSH. TRH may be necessary not only for the release but also for the formation of the normal TSH molecule.
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Krawczynska, H., Illig, R. & Prader, A. ELEVATED BASAL PLASMA TSH IN CHILDREN WITH GROWTH HORMONE (GH) DEFICIENCY AND HYPOTHALAMIC HYPOTHYROIDISM. Pediatr Res 9, 682 (1975). https://doi.org/10.1203/00006450-197508000-00091
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DOI: https://doi.org/10.1203/00006450-197508000-00091