About this test

Calcium – Serum measures the calcium circulating in your blood — the mineral doing far more than building bones. Blood calcium drives muscle contraction, nerve signalling, clotting and heart rhythm, which is why the body guards its blood calcium level fiercely, pulling from bone when intake falls short.

An abnormal serum calcium points in several directions: high values raise questions about parathyroid glands, vitamin D excess or certain illnesses; low values suggest vitamin D deficiency, kidney issues or absorption problems. It is a common component of bone panels, kidney workups and general screening.

The test is a single home blood draw, ideally in the morning. Tell your doctor about any calcium or vitamin D supplements you take — timing matters for interpretation. Reports are released in the app, usually within a day.