About the test
Calcium is one of the most important minerals in the human body. It is mainly stored in bone and a small amount is circulating in blood either free or bound to proteins such as albumin.
Calcium is required for the proper function of heart, nerves and muscles. Its role is vital in bone formation as well as in blood clotting.
Sample
Venous blood
Preparation
- 12 hours fasting prior to testing.
- No intake of food supplements containing Calcium.
- Cessation of lithium, vitamin D, antiacid and diuretic drugs.
- Water is permitted.
Procedure
Venipuncture (Tourniquet use or prolonged fist clenching should be avoided)
Increased values
- Primary hyperparathyroidism
- Renal failure
- Hyperthyroidism
- Lung cancer. Kidney cancer
- Metastatic bone cancer
- Acromegaly
- Addison’s disease, Paget’s disease
- Respiratory acidosis
- Sarcoidosis
- Prolonged immobilization
- Drugs (lithium, thiazide diuretics)
- Excessive intake of calcium or vitamin D
Decreased values
- Hypoparathyroidism
- Pancreatitis
- Chronic renal disease
- Alcoholism
- Osteomalacia
- Vitamin D insufficiency
- Diarrhea
- Hyperphosphatemia
- Rachitis
- Drugs (antacids, aspirin, corticosteroids, insulin, methicillin, laxatives)
- Calcium malabsorption
- Low levels of albumin
Additional information
Serum calcium levels are controlled by two hormones: calcitonin and parathormone.
Calcitonin (CT) enhances calcium excretion from the kidneys, lowering therefore its concentration in blood.
Parathormone (PTH), releases calcium from blood and bones when necessary, increasing hence its absorption from the kidneys and the intestine.