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Test Code Billings Clinic: 3988 Ionized Calcium, Serum

Performing Laboratory

Billings Clinic Laboratory:  Chemistry

Useful For

Calcium in serum exists ionized, bound to organic anions such as phosphate and citrate, and bound to proteins (mainly albumin). Of these, ionized calcium is the physiologically important or true “bioavailable” form in the circulation. Measurement of serum ionized calcium provides insight into the effect of total protein and albumin on serum calcium levels. A patient can have high total calcium with normal ionized calcium and increased total protein and/or albumin, as in dehydration or in myeloma. There is an inverse relationship between ionized calcium and phosphate concentration.

 

Used in the diagnosis and treatment of hypertension, renal disease and vitamin D related disorders. Also useful in the diagnosis and treatment of patients with increased total protein and/or albumin levels as in dehydration.

Methodology

Ion Selective Electrode/pH (ISE)

Specimen Requirements

Container/Tube: Serum gel

Collection/Transport Instructions:

  1. Allow blood to clot for 30 minutes.
  2. Centrifuge at 1000 RCF for 10 - 15 minutes.
  3. Aliqout 1 mL serum into an aliquot tube
  4. Cap immediately to preserve anaerobic conditions as much as possible
  5. Transport frozen.

Storage/Stability

Specimen Type Temperature Time
Serum Refrigerated 48 hours
  Frozen (preferred) 6 months
  Ambient 8 hours

Reject Due To

  • EDTA, citrate, oxalate, and sodium fluoride are not recommended for use
  • Hemolysis
  • Specimens not received frozen if greater than 48 hours old

 

Reference Values

Reference Range:

0 hrs. to 31 days:               1.00 – 1.50 mmol/L

31 days to 6 months:         0.95 – 1.50 mmol/L

6 months to 18 yrs.:          1.22 – 1.37 mmol/L

18 yrs. to 150 yrs.:            1.10 – 1.30 mmol/L

 

Critical Range:

<0.8 mmol/L

>1.60 mmol/L

 

Day(s) Test Set Up

Daily

Test Classification and CPT Coding

82330 - Calcium; ionized

LOINC Code Information

Reporting Name LOINC Code
Calcium, Ionized, Serum 12180-6
Calcium Ionized pH 7.4 19072-8