Calcium (Total)

Bone, nerve, and muscle mineral — disrupted by certain cancers and drugs.

What it is

Total serum calcium includes calcium bound to albumin and free (ionised) calcium. It is involved in bone metabolism, nerve transmission, muscle contraction, and hormonal signalling.

Why it matters

Hypercalcaemia (high calcium) is a known complication of some cancers, caused by bone metastases or paraneoplastic PTHrP secretion. Symptoms include fatigue, confusion, nausea, and constipation. It is a medical emergency at high levels. Hypocalcaemia occurs with magnesium deficiency or surgical parathyroid damage.

How to test

Standard metabolic panel. Interpret alongside albumin (low albumin falsely lowers total calcium).

This information is for educational purposes only. Always discuss testing and interpretation of results with your care team.

Optimal range

Below 2.2 mmol/L

hypocalcaemia — review magnesium and vitamin D

2.2–2.6 mmol/L

normal

Above 2.6 mmol/L

hypercalcaemia — investigate if persistent

How often

Each oncology blood panel.