title: Undetectable serum calcidiol: not everything that glitters is gold.
abstract: There is an increased awareness of the adverse consequences of nutritional vitamin D deficiency. We report a patient with chronic tophaceous gout, chronic kidney disease (CKD) Stage 3/4 and undetectable serum calcidiol who developed severe hypercalcaemia upon vitamin D supplementation despite serum 25(OH) vitamin D within the normal range. Upon recovery, serum 1,25(OH)2 vitamin D remained in the normal range despite CKD and serum 25(OH) vitamin D 6 ng/mL. Gout tophi biopsies from additional patients showed macrophage expression of 25(OH) vitamin D 1α-hydroxylase. This case illustrates the dangers of supplementing vitamin D in patients with low serum 25(OH) vitamin D and increased 1α-hydroxylase activity due to granulomatous disease.
authors.affiliation: Department of Family and Community Medicine, Centro de Salud Barrio del Pilar, Area 5, Madrid, Spain.
authors.forename: Gioconda
authors.initials: G
authors.lastname: Gallegos-Bayas
authors.affiliation: Department of Internal Medicine, Hospital Cantoblanco-La Paz, Universidad Autonoma de Madrid, Madrid, (IdiPAZ), Spain.
authors.forename: José Francisco
authors.initials: JF
authors.lastname: Pascual-Pareja
authors.affiliation: Department of Nephrology, IIS-Fundacion Jimenez Diaz, Universidad Autonoma de Madrid, Madrid, Spain.
authors.forename: Maria D
authors.initials: MD
authors.lastname: Sanchez-Niño
authors.affiliation: Department of Pathology, IIS-Fundacion Jimenez Diaz, Universidad Autonoma de Madrid, Madrid, Spain.
authors.forename: Felix
authors.initials: F
authors.lastname: Manzarbeitia
authors.affiliation: Department of Nephrology, IIS-Fundacion Jimenez Diaz, Universidad Autonoma de Madrid, Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Ortiz
keywords: 1,25(OH)2 vitamin D; 25-hydroxyvitamin D-1α hydroxylase; CYP24; chronic tophaceous gout; vitamin D deficiency