title: Calcium, magnesium, and phosphorus: emergency department testing yield.
abstract: OBJECTIVE
  To investigate how often the ED ordering of stat serum calcium (Ca+2), magnesium (Mg+2), and phosphorus (PO4(-3)) levels affected clinical treatment; to define the diagnoses of patients for whom Ca+2, Mg+2, and PO4(-3) measurements did affect clinical therapy; and to suggest guidelines for more appropriate ordering of these laboratory tests.
  
  
  METHODS
  A retrospective chart review was performed in an academic teaching hospital. All adult ED patients who had Ca+2, Mg+2, or PO4(-3) laboratory testing during the 9-month study period were included and evaluated for potential clinical impact of an abnormal Ca+2, Mg+2, or PO4(-3) laboratory test.
  
  
  RESULTS
  1.477 patients had Ca+2, Mg+2, or PO4(-3) measured while in the ED during the study period. Of these, 260 patients (17.6%) had a total of 312 abnormal Ca+2, Mg+2, or PO4(-3) values as defined by results exceeding +/- 15% of normal reference values. Of these, only 5 patients (0.3%) received treatment for abnormal values in the ED, while 75 patients (5.1%) were treated once admitted to the hospital. In this study, the only diagnostic groups to whom significant treatment was administered were diabetic patients (Ca+2 and PO4(-3); alcoholic patients (Mg+2); and renal failure patients (Ca+2, Mg+2, and PO4(-3).
  
  
  CONCLUSIONS
  These results suggest that stat Ca+2, Mg+2, and PO4(-3) levels seldom affect clinical treatment in the ED. The frequency of ordering these tests may be reduced by obtaining Ca+2, Mg+2, or PO4(-3) measurements only for patients known to be at risk for such abnormalities, based on their existing or suspected diagnoses. The authors suggest obtaining these tests, when indicated, on a "non-stat" basis, with the subsequent laboratory results becoming available in-hospital, where treatment is more likely to occur.
authors.affiliation: Department of Emergency Medicine, West Virginia University School of Medicine, Morgantown 26506, USA. brose@access.mountain.net
authors.forename: W D
authors.initials: WD
authors.lastname: Rose
authors.forename: J E
authors.initials: JE
authors.lastname: Martin
authors.forename: F M
authors.initials: FM
authors.lastname: Abraham
authors.forename: R L
authors.initials: RL
authors.lastname: Jackson
authors.forename: J M
authors.initials: JM
authors.lastname: Williams
authors.forename: E
authors.initials: E
authors.lastname: Gunel
mesh_terms: D000328:Adult; D001774:Blood Chemical Analysis / Q000706:statistics & numerical data*; D002118:Calcium / Q000097:blood; D019411:Clinical Laboratory Techniques; D003955:Diagnostic Tests, Routine / Q000706:statistics & numerical data*; D004573:Electrolytes / Q000097:blood*; D004630:Emergencies; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D006784:Hospitals, Teaching; D006801:Humans; D008274:Magnesium / Q000097:blood; D010758:Phosphorus / Q000097:blood; D017410:Practice Guidelines as Topic; D014903:West Virginia
chemical_list: D004573:Electrolytes; D010758:Phosphorus; D008274:Magnesium; D002118:Calcium