Calcium, Total

Additional Information:

UFHPL Epic order code: LAB53

CPT Code(s):


Specimen Requirements:

Type: Urine, 24-hour collection

Container/Tube: Plastic urine container

Sample Volume: Entire 24-hour collection

Preparation: Acidify the urine specimen with 6 N HCl to a pH < 2.


  • Sample is stable 5 days at 15 – 25°C
  • Sample is stable 5 weeks at 2 – 8ºC


This Calcium procedure is based on calcium ions (Ca2+) reacting with Arsenazo III (2,2’-[1,8-Dihydroxy-3,6-disulphonaphthylene-2,7-bisazo]- bisbenzenear-sonic acid) to form an intense purple colored complex.2,3 Magnesium does not significantly interfere in calcium determination using Arsenazo III. In this method the absorbance of the Ca-Arsenazo III complex is measured bichromatically at 660/700 nm. The resulting increase in absorbance of the reaction mixture is directly proportional to the calcium concentration in the sample. (Package Insert: OSR General Chemistry BAOSR6x117.05, 2014-04)


Within 24 hours

Reference Values:

100 – 300 mg/day