title: Association of Hyponatremia and Hypovitaminosis D in Ambulatory Adults.
abstract: BACKGROUND
  Hyponatremia and vitamin D deficiency are frequent disorders, and both have been associated with gait disturbances, falls and fractures. The aim of this study was to evaluate the existence of an association between serum sodium and vitamin D serum levels.
  
  
  METHODS
  We performed a retrospective investigation to establish whether hyponatremia and vitamin D deficiency may be associated in a general population of unselected outpatients. An electronic search was performed in the laboratory information systems of the Hospital of Verona and the Hospital of Parma (Italy), to retrieve combined results for total vitamin D and sodium obtained in all outpatients referred for health check-up in the year 2013.
  
  
  RESULTS
  Combined results of vitamin D and sodium could be retrieved for 5097 outpatients (3859 females and 1238 males; mean age 64±17 years). Vitamin D deficient subjects displayed significantly lower levels of serum sodium (140 versus 141 mmol/L; p<0.001), along with a significantly higher rate of hyponatremia (6.3% versus 5.1%; p=0.037). Accordingly, hyponatremic subjects had significantly lower levels of serum vitamin D (55 versus 60 nmol/L; p=0.015), along with a significantly higher rate of vitamin D deficiency (41.8% versus 36.1%; p=0.030). A highly significant correlation was found between sodium and total vitamin D after adjustment for age and gender (p<0.001).
  
  
  CONCLUSIONS
  The results of this study demonstrate for the first time the existence of a significant correlation between the serum levels of sodium and total vitamin D in a general population of unselected outpatients.
authors.affiliation: Emergency Department, Academic Hospital of Parma, Parma, Italy.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Cervellin
authors.affiliation: Laboratory of Clinical Chemistry and Hematology, University of Verona, Verona, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Salvagno
authors.affiliation: Emergency Department, Academic Hospital of Parma, Parma, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Bonfanti
authors.affiliation: Laboratory of Clinical Chemistry and Hematology, Academic Hospital of Parma, Parma, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Bonelli
authors.affiliation: Laboratory of Clinical Chemistry and Hematology, University of Verona, Verona, Italy.
authors.forename: Gian Cesare
authors.initials: GC
authors.lastname: Guidi
authors.affiliation: Laboratory of Clinical Chemistry and Hematology, Academic Hospital of Parma, Parma, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lippi
keywords: elderly; hyponatremia; osteoporosis; sodium; vitamin D