A phosphate test measures the level of phosphate in the blood.
It is particularly useful for measuring phosphate levels in people who are malnourished (not receiving enough nutrients to meet their body's demands).
A phosphate test can also be used to test people being treated for ketoacidosis. Ketoacidosis sometimes affects people with diabetes. It is where the body cannot use blood glucose as an energy source due to a lack of insulin (a hormone that controls blood sugar levels).
Phosphate tests can also help diagnose digestive system disorders that interfere with the absorption of phosphate, calcium and magnesium.