Calcium, Ionized, Serum



Quest Diagnostics Test Code: 306

The ionized calcium is determined by an ion selective electrode methodology. In situations where the total calcium is normal but does not fit the clinical picture, e.g., hyperparathyroidism, a determination of the ionized calcium will, many times, show an elevation in the “bioavailable” calcium component.

Calcium is the most abundant vital mineral found in the body which is needed for essential functions. Calcium is required in proper cell signalling mechanisms and for the function of the muscles, heart and nerves. Additionally, calcium is important in the clotting and coagulation cascade and for the maintenance of the density of bones. Calcium gets in the body via diet or supplements. The amount of calcium in the body is very closely regulated because too little or too much are both potentially fatal. This test is used to detect calcium levels. Ionized calcium test only measures the free, metabolically active calcium and is just as effective as a normal total calcium test.

This test is performed in following conditions such as:

• Kidney disease
• Symptoms of high calcium
• Fatigue and weakness
• Nausea, vomiting and constipation
• Abdominal pain
• Symptoms of very low calcium
• Abdominal and muscle cramps
• Tingling fingers
• Parathyroid disorder
• Malabsorption

Also Known As: Calcium Free, Calcium Unbound, Calcium Filterable, Ca++ Ionized


The Calcium, Ionized test has no fasting requirements.


Specimen Collected
  • Blood
Estimated Time Taken

Turnaround time for the Calcium, Ionized test is typically 1-2 business days.