Calcium

Calcium is the most abundant mineral element in the body with about 99 % in the bones primarily as hydroxyapatite. The remaining calcium is distributed between the various tissues and the extracellular fluids where it performs a vital role for many life sustaining processes. Among the extra skeletal functions of calcium are involvement in blood coagulation, neuromuscular conduction, excitability of skeletal and cardiac muscle, enzyme activation, and the preservation of cell membrane integrity and permeability.

Serum calcium levels and hence the body content is controlled by parathyroid hormone (PTH), calcitonin, and vitamin D. An imbalance in any of these modulators leads to alterations of the body and serum calcium levels. Increases in serum PTH or vitamin D are usually associated with hypercalcemia. Increased serum calcium levels may also be observed in multiple myeloma and other neoplastic diseases. Hypocalcemia may be observed e.g. in hypoparathyroidism, nephrosis, and pancreatitis.

Useful For

In vitro test for the quantitative determination of calcium in human serum, plasma and urine on Roche/Hitachi cobas c systems.

Method Name

Calcium ions react with 5-nitro-5’-methyl-BAPTA (NM-BAPTA) under alkaline conditions to form a complex. This complex reacts in the second step with EDTA. The change in absorbance is directly proportional to the calcium concentration and is measured photometrically.

Aliases

Calcium; Calcium, Serum; Ca, Calcium - Blood

Specimen Type

Plasma or serum

Specimen Required

Lithium heparin plasma separator tube is preferred but serum separator tube (SST) is also acceptable. If using an SST, please allow 20 minutes after collection for specimen to clot before centrifugation. All specimens must be centrifuged within four hours of collection.

Specimen Minimum Volume

0.5 mL of blood

Specimen Stability Information

Centrifuged specimen stable for 72 hours refrigerated.

Performing Laboratory

Glens Falls Hospital Chemistry and Special Chemistry Department

Reference Values

8.6-10.0 mg/dL

Day(s) and Time(s) Performed

As ordered, 4 hour turn around time