ECE2015 Oral Communications Steroids, developmental and paediatric endocrinology (5 abstracts)
Pituitary hormone secretion profiles in IGSF1 deficiency syndrome
Sjoerd Joustra 1 , Ferdinand Roelfsema 1 , Erik Endert 2 , Bart Ballieux 1 , Paul van Trotsenburg 2 , Eric Fliers 2 , Noortje Corssmit 1 , Daniel Bernard 3 , Wilma Oostdijk 1 , Jan-Maarten Wit 1 , Alberto Pereira 1 & Nienke Biermasz 1
1Leiden University Medical Center, Leiden, The Netherlands; 2Academic Medical Center, Amsterdam, The Netherlands; 3McGill University, Montréal, Canada.
Context: Loss-of-function of immunoglobulin superfamily 1 (IGSF1) causes an X-linked syndrome of central hypothyroidism, macroorchidism, and variable prolactin deficiency, GH deficiency in childhood, delayed pubertal testosterone rise, and/or obesity. The clinical features advert towards a pivotal role for IGSF1 in the pituitary gland, but detailed knowledge on pituitary hormone secretion in this syndrome is lacking.
Objective: To study detailed 24 h spontaneous pituitary hormone secretion in patients with the IGSF1 deficiency syndrome.
Methods: We performed a 24 h sampling study with measurements every 10 min in eight IGSF1 deficient patients. Deconvolution, modified cosinor, and approximate entropy (ApEn) analyses were applied to quantify TSH, prolactin, and gonadotropin secretion rates, diurnal rhythmicity, and regularity of hormone release. Results were compared to matched healthy controls or (for TSH) patients with subclinical primary hypothyroidism (SCH).
Results: Compared to both healthy controls and SCH, IGSF1 deficient patients showed decreased pulsatile secretion of TSH with decreased disorderliness and absence of diurnal variation. Basal and pulsatile secretion of FSH was increased, while LH secretion was not different from healthy controls. For prolactin secretion, two phenotypes were observed, with absence of prolactin secretion in some and increased basal and total prolactin secretion in others.
Conclusion: The TSH secretion pattern is consistent with the previously proposed hypothesis of defective TRH signalling in IGSF1 deficiency, which is further supported by a decreased TSH response to TRH in patients, and the decreased expression of pituitary Trhr mRNA in IGSF1 knock-out mice. However, the increased FSH and prolactin secretion, but normal LH secretion, in combination with the delayed puberty despite normal testicular growth, have been observed in untreated primary hypothyroidism, and provoke some novel hypotheses.
Volume 37
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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