Serum Calcium

Calcium is one of the most common minerals in the body. In your blood, calcium exists in two forms: ionized (free) and bound (attached to proteins like albumin). The Serum Calcium measures total calcium, which includes both types.

The Serum Calcium test is usually done if you have:

• Muscle cramps or spasms
• Tingling in your hands or feet
• Fatigue or weakness
• Bone pain
• Irregular heartbeat
• Confusion
• Perioral numbness
• Tetany
• Seizures

Calcium blood test also helps diagnose and monitor calcium metabolism problems, parathyroid or kidney diseases, bone disorders, and how treatments are working in very ill patients.

Low calcium levels are called hypocalcemia. This can happen due to:

• Vitamin D deficiency
• Kidney problems
• Low parathyroid hormone
• Hypoparathyroidism (post-thyroid/parathyroid surgery, autoimmune)
• Chronic kidney disease (CKD)
• Acute pancreatitis
• Sepsis & critical illness
• Hypoalbuminemia (pseudo-hypocalcemia)
• Magnesium deficiency
• Medications: bisphosphonates, calcitonin, phenytoin

High calcium levels are called hypercalcemia. This can occur because of:

• Overactive parathyroid glands
• Certain cancers
• Kidney disease
• Too much calcium intake
• Primary hyperparathyroidism
• Malignancy (lytic bone lesions, myeloma)
• Excess Vitamin D or calcium intake
• Sarcoidosis / granulomatous disorders
• Thiazide diuretics
• Immobilization
• Thyrotoxicosis

An overnight fast (8-12 hours) is preferred but not mandatory for serum calcium test preparation. Always tell your doctor about any medicines or supplements you take, as these can affect calcium levels. 

Test results can vary slightly between labs. Talk to your doctor to understand your test results. Your doctor will suggest the best treatment or lifestyle changes based on your test results.