Endocrine https://doi.org/10.1007/s12020-019-01998-7 RESEARCH LETTER Sweat and vitamin D status in congenital, lifetime, untreated GH deficiency Cynthia S. Barros-Oliveira 1 ● Roberto Salvatori 2 ● Jéssica S. S. dos Santos 1 ● Paula F. C. Santos 1 ● Alécia A. Oliveira-Santos 1 ● Cindi G. Marinho 1 ● Elenilde G. Santos 1 ● Ângela C. G. B. Leal 1 ● Viviane C. Campos 1 ● Nayra P. Damascena 1 ● Carla R. P. Oliveira 1 ● Manuel H. Aguiar-Oliveira 1 Received: 22 May 2019 / Accepted: 28 June 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract Purpose A reciprocal relationship exists between the skin and the GH/IGF-I axis. Skin produces both IGF- I and vitamin D, and GH and IGF-I exert several actions in the skin. Reduced sweating and altered phosphor-calcium homeostasis are occasionally reported in subjects with GH deficiency (GHD), mostly in the setting of hypopituitarism, therefore associated to other hormonal deficiencies. It is unclear whether these findings are due to GHD. The aim of this study was to assess skin function in subjects with isolated GHD (IGHD) due to a mutation in the GHRH receptor gene. Methods In a cross-sectional study we enrolled 20 IGHD and 20 local controls. Sweating (volume, conductivity and chloride content) was assessed by a 30 min pilocarpine iontophoresis test, using the Macroduct® Sweat Collection System. IGF-I, Insulin, PTH, 25-hydroxyvitamin D, C-reactive protein (CRP), CPK, glucose, calcium, phosphate, alkaline phos- phatase, total proteins and fractions, urinary calcium, and insulin were measured. HOMA-IR was calculated. Results IGHD presented lower sweating, but normal vitamin D and phosphor-calcium homeostasis. Additionally, IGHD subjects presented lower HOMA-IR, higher CRP and reduced CPK. Conclusion Untreated IGHD cause reduction in sweating, but does not affect phosphor-calcium homeostasis. KeyWords GH deficiency ● skin ● sweat ● vitamin D Introduction Skin has many functions, some protective (against micro- organisms, dehydration, ultraviolet light, and mechanical damage) and other homeostatic (sweating and production of vitamin D). A mutual influence exists between the skin and the growth hormone/insulin growth factor I (GH/IGF-I) axis. Skin produces IGF-I and vitamin D, and GH and IGF-I exert several actions on the skin [1, 2]. Therefore, altera- tions of the GH–IGF-I axis may influence sweating and the phosphorus–calcium homeostasis. Sweating is essential for thermoregulation, exercise capacity, and exposure to high ambient temperatures [3]. Patients with childhood-onset GH deficiency (COGHD) have impaired sweating ability [3]. Sweating impairment has been also reported in men with adult-onset GHD [4]. Laron’s dwarfs, affected by GH insensitivity, also exhibit impaired sweating ability [5]. During exposure to sunlight, ultraviolet radiation pene- trates into the epidermis and photolyzes the synthesis of vitamin D. A variable prevalence of vitamin D insufficiency or deficiency has been described in patients with GHD, and the latter was suggested to be a risk factor for vitamin D deficiency [6–8]. We have identified in northeast Brazil a cohort of sub- jects with severe isolated GHD (IGHD) caused by a homozygous (c.57+1G>A) mutation in the GHRH receptor gene (GHRHR)[9]. These individuals have normal long- evity and quality of life and are quite active [10], coping well with their environmental challenges, often working outdoor under high solar exposure [11, 12]. The objectives of this study were to evaluate sweating, vitamin D * Roberto Salvatori salvator@jhmi.edu 1 Division of Endocrinology, Federal University of Sergipe, Aracaju, Sergipe 49060-100, Brazil 2 Division of Endocrinology, Diabetes and Metabolism, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA 1234567890();,: 1234567890();,: