title: Prevalence of hypercalcemia related to hypervitaminosis D in clinical practice.
abstract: Recent interest in vitamin D has led to a substantial increase in the use of vitamin D supplements. Vitamin D intoxication may be a concern as hypervitaminosis D can result in irreversible calcification of soft tissues so that it is important to detect early markers of vitamin D intoxication. Our aim was to assess the simultaneous presence of biochemical markers of vitamin D toxicity (i.e. hypervitaminosis D, hypercalcemia) and determine the concentrations of 25-OH-vitamin D at which the risk of hypercalcemia, and thus toxicity, might begin.
  
  
  
  We evaluated retrospectively a 6-year period during which 25.567 samples were assessed for 25-OH-vitamin D status by UHPLC. Hypervitaminosis D was defined at serum 25-OH-vitamin D >160 nmol/L. Serum and urine calcium, phosphorus and iPTH were also recorded, if available. Medical history revision was performed in subjects displaying simultaneously hypervitaminosis D and hypercalcemia.
  
  
  
  Overall, hypervitaminosis D was found in 475 samples (1.86%) of which 51 displayed hypercalcemia (11.1%). A total of 382 samples were identified as the first record of hypervitaminosis D and 39 presented hypercalcemia (10.2%), most of them at 25-OH-vitamin D levels between 161 and 375 nmol/L. Only in 15 subjects, hypercalcemia could be directly attributed to vitamin D and serum 25-OH-vitamin D ranged between 164 and 1139 nmol/l. In no case, serum calcium achieved concentrations considered as critical values (>13 mg/dl).
  
  
  
  Hypercalcemia due to vitamin D represented <4% of the total hypervitaminosis D detected and <0.1% of the tests performed. However, a highly variable response was observed and most subjects presented hypercalcemia at serum concentrations of 25-OH-vitamin D < 375 nmol/L.
authors.affiliation: Servicio de Bioquímica Clínica, Hospital Universitario Puerta de Hierro-Majadahonda, 28222, Madrid, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Pérez-Barrios
authors.affiliation: Servicio de Bioquímica Clínica, Hospital Universitario Puerta de Hierro-Majadahonda, 28222, Madrid, Spain; Unidad de Vitaminas, Hospital Universitario Puerta de Hierro-Majadahonda, 28222, Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Hernández-Álvarez
authors.affiliation: Servicio de Bioquímica Clínica, Hospital Universitario Puerta de Hierro-Majadahonda, 28222, Madrid, Spain; Unidad de Vitaminas, Hospital Universitario Puerta de Hierro-Majadahonda, 28222, Madrid, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Blanco-Navarro
authors.affiliation: Unidad de Vitaminas, Hospital Universitario Puerta de Hierro-Majadahonda, 28222, Madrid, Spain.
authors.forename: B
authors.initials: B
authors.lastname: Pérez-Sacristán
authors.affiliation: Servicio de Bioquímica Clínica, Hospital Universitario Puerta de Hierro-Majadahonda, 28222, Madrid, Spain; Unidad de Vitaminas, Hospital Universitario Puerta de Hierro-Majadahonda, 28222, Madrid, Spain. Electronic address: fgranado.hpth@salud.madrid.org.
authors.forename: F
authors.initials: F
authors.lastname: Granado-Lorencio
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002118:Calcium / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000097:blood / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012189:Retrospective Studies; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D002118:Calcium
keywords: Clinical practice; Hipervitaminosis D; Hypercalcemia; Vitamin D status; Vitamin D toxicity