Calcium

Total calcium measures the overall amount of calcium circulating in your blood, including both the portion bound to proteins like albumin and the free, active fraction. Calcium is essential for building strong bones and teeth, muscle contraction, nerve signalling, blood clotting, and maintaining a steady heartbeat. Your body regulates calcium very tightly, so even small deviations outside the normal range can produce noticeable symptoms.

A raw total calcium reading is useful as a quick check, but it is influenced by your albumin level. About half the calcium in your blood travels bound to albumin, so when albumin is abnormal, the total calcium value may under- or over-state your true calcium status. This is why labs typically report both total calcium and corrected calcium (adjusted for albumin), the two are read together. For most people with normal albumin, total calcium and corrected calcium are effectively interchangeable.

Low total calcium can cause tingling in the fingers, muscle cramps, and occasionally muscle spasms. Common causes include vitamin D deficiency, low albumin, underactive parathyroid glands, kidney impairment, and magnesium deficiency. High total calcium can produce fatigue, excessive thirst, frequent urination, constipation, and confusion; the most frequent causes are hyperparathyroidism, excessive vitamin D supplementation, prolonged immobility, and dehydration (which can falsely elevate the reading). Your GP will interpret total calcium alongside corrected calcium, albumin, vitamin D, parathyroid function, and kidney function to build an accurate picture.

If your total calcium falls outside the expected range, your GP can arrange further investigation to identify the cause and advise on appropriate next steps.