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Lab Manual for Moffitt-Long and Mount Zion

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Calcium, total, 24 hour urine

Item Value
Approval req'd? Yes, if testing is requested between midnight and 8:00 AM.
Available Stat? No
Test code CAU
Test group Calcium
Performed by Parnassus Chemistry
In House Availability Test available 7 days per week from 8:00 AM to midnight only.
Method Ion selective electrode
Container type 24 hour urine collection container

Click here for Urine Preservative Requirements
Amount to Collect Entire 24 hour urine output.
Sample type 24 hour urine collection
Preferred volume 2 mL urine
Min. Volume 1 mL urine
Processing notes Aliquot 1 mL and add 1 drop of 6N HCl to acidify.
Units mg/D
Normal range Usually 100-300 mg/D
Synonyms Ca; Ca++
Stability Refrigerated 2 days
Turn around times Day & evenings 4 hours. Samples received after 2000 hours will be tested the following day.
Additional information To convert mg/dL to mmol/L (SI units) multiply by 0.25

Output varies with the diet. 24 hour specimens are preferable; a urine creatinine should be ordered on a spot specimen in order that any comparison of results in serial specimens can be normalized for creatinine excretion.

Gadolinium MR contrast agents including Gadodiamide (Omniscan), Gadoversetamide (Optimark), Gadopentetate Dimeglumine (Magnevist), and Gadoterdiol (Prohance), have been shown to interfere with certain colorimetric assays used in the measurement of various serum cations including iron, magnesium, and calcium. The UCSF clinical labs use electrode methods for measurement of total and ionized calcium levels which have not been reported to be subject to the gadolinium interference.

Reference:Proctor et al. Gadolinium Magnetic Resonance contrast Agents produce Analytic Interference in Multiple Serum Assays. Am J Clin Pathol. 2004;121:282-292.
Last Updated 3/24/2013 7:38:43 PM
Entry Number 162
Lab Procedure Link Click here for Procedure

If you have additional questions regarding this test, please call: 415-353-1667

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