Serum Calcium (Total)

Specimen Required

3-5cc Clotted Blood or Serum

Fasting Required

Purpose of the Serum Calcium (Total) Test

To determine the concentration of calcium in your blood

When this Serum Calcium (Total) test is required

For Diagnosis: Calcium can be used as a diagnostic test if individuals have symptoms that suggest:: kidney stones bone disease, or neurologic (nerve-related) disorders.Doctor may also request a calcium test if individuals have: kidney disease, because low calcium is common in those with kidney failure symptoms of excessive calcium, such as thirst, frequent or excessive urination, constipation, tiredness, weakness, loss of appetite or nausea and vomiting symptoms of low calcium, such as abdominal/muscle cramps, tingling fingers, numbness around the mouth, or convulsions other diseases that can be associated with abnormal blood calcium, such as thyroid disease, intestinal disease, cancer, or poor nutritionHowever, if calcium levels fall slowly many people have no symptoms at all.For Monitoring: Patients with certain kinds of cancer (particularly breast, lung, head and neck, kidney, and multiple myeloma), kidney disease or transplant may need calcium monitoring as part of their regular laboratory tests. Additionally, patients receiving calcium or vitamin D supplements may also need to have their calcium concentration monitored.Urine calcium may be requested if individuals have symptoms of kidney stones, such as sharp pain in the side or back around the kidneys, pain that may progress to lower abdomen, and/or blood in the urine.

What the Serum Calcium (Total) Test Detects

Calcium is one of the most important minerals in the body, required for proper functioning of muscles, nerves, heart, as well as essential in blood clotting and bone formation. About 99% of calcium is found in the bones, while most of the rest circulates in the blood. In the blood, roughly half of the calcium is ‘ionised’ (or free) and is active; the remaining half, is bound to proteins, such as albumin, or complexed with other compounds, such as phosphate and bicarbonate, and is inactive.Most commonly, laboratories report a value for ‘adjusted calcium’, (also known as corrected calcium), which is the measured calcium value adjusted for the albumin concentration. This is because abnormally high or low albumin concentrations can alter total calcium concentration independently of ‘ionised’ (active) calcium concentration. Therefore, ‘adjusted calcium’ gives a better indication of the ‘ionised’ levels.In some conditions, such as during major surgery (particularly after a blood transfusion), in critically ill patients, and patients with abnormal protein concentration, measurement of ‘ionised’ is needed, as ‘adjusted calcium’ level is likely to be misleading in these situations. In these situations, ‘ionised’ calcium is measured on specific analysers known as blood gas analysers or point of care (POC) analysers; thus special sample handling is required.Urine calcium is used to indicate how much calcium is being excreted by the kidneys.

Preparation for the Serum Calcium (Total) Test

Current practice does not require fasting or any other test preparation. However, it is advisable that prolonged tourniquet use and fist clenching during collection of the blood sample should be avoided as this may affect the generated result.

Sample Requirements

A blood sample taken from a vein in your arm; a urine collection may also be requested when blood calcium concentration is abnormal. Urine calcium measurements may also be requested if you have kidney stones.

Additional Notes

Blood and urine calcium measurements cannot be used to assess how much calcium is in the bones. A test similar to an X-ray, called a bone density or ‘Dexa’ scan, is needed for this purpose.

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