Vitamins & minerals
Phosphate blood test
A phosphate blood test measures a mineral that works closely with calcium to build bones and teeth and to power your cells. Its level is controlled by the kidneys, parathyroid hormone and vitamin D, so an abnormal result often points towards one of these systems.
- What it measures
- Phosphate, a mineral for bones and cellular energy
- Sample
- Venous blood sample
- Fasting
- Preferred (a fasting morning sample)
- Also known as
- serum phosphate, phosphorus
- Included in 57 Health tests
- 2 panels, from £160
Phosphate reference range
Guide only| Category | Guide range |
|---|---|
| Adults | 0.8–1.5 mmol/L |
Phosphate is regulated by the kidneys, parathyroid hormone and vitamin D, and it varies through the day (so a fasting morning sample is preferred). Ranges are higher in children. Values vary by laboratory.
These are general UK adult guide ranges from public health sources, shown for orientation only. Reference ranges vary by laboratory, assay, age and sex, so your result is always interpreted against the range quoted by the analysing laboratory on your report.
What does a high phosphate level mean?
A high phosphate is most often linked to reduced kidney function, since the kidneys normally clear excess phosphate. It can also relate to parathyroid or vitamin D issues.
It's interpreted alongside kidney function, calcium and, where relevant, parathyroid hormone and vitamin D.
What does a low phosphate level mean?
A low phosphate can result from poor intake or absorption, vitamin D deficiency, certain hormone imbalances, or shifts of phosphate into cells (for example after refeeding or in some acute illnesses).
Marked or persistent low phosphate can affect muscles and bones, so it's interpreted alongside calcium and vitamin D.
When to consider a phosphate test
- Assessing kidney or bone health
- Alongside calcium and vitamin D
- Investigating a parathyroid problem
- Muscle weakness or bone symptoms
Frequently asked questions
This page is general information about a blood marker and is not medical advice or a diagnosis. A phosphate test screens and gives context; results are interpreted by a clinician alongside your symptoms, history and other markers. Always follow the guidance on your own report.