How to prepare
No fasting required for a standard serum calcium test. Drink water as normal.
Let your practitioner know about any calcium supplements, vitamin D, antacids or medications you take regularly, as these can affect results. Your practitioner may advise whether to pause any supplements before testing. A healthcare professional will take a blood sample from a vein in your arm.
After the test
Share your results with your GP or a relevant specialist. If your calcium is outside the reference range, your practitioner may request additional tests such as parathyroid hormone (PTH), vitamin D (25-OH), phosphate, albumin, or kidney function markers.
If your result is normal but you have ongoing symptoms, your practitioner may investigate other causes.
Your test results will be available in your private dashboard. If there are any urgent issues, we'll let you know so you can follow up with your health professional.
Understanding results
Results are reported as total serum calcium in millimoles per litre (mmol/L). The reference range for adults is typically 2.10 to 2.60 mmol/L, though this can vary slightly between laboratories.
Levels above the reference range (hypercalcaemia) may be associated with overactive parathyroid glands, excess vitamin D, certain bone conditions, or other causes. Levels below the reference range (hypocalcaemia) may be associated with low parathyroid hormone, vitamin D deficiency, magnesium deficiency, or kidney conditions.
A single result outside range does not confirm a diagnosis. Your practitioner will review your result alongside symptoms, medications, and other test findings before drawing conclusions or recommending further investigation.