Kidney & Electrolytes
Ionised Calcium (Free)
Kidney & Electrolytes
Ionized calcium is the biologically active fraction of calcium that directly influences muscle contractions, nerve signalling, and bone health.
VAT-exempt medical service
Unlike total calcium, which includes both protein-bound and free forms, ionized calcium measures only the portion that is freely available to the body. This makes it the more clinically relevant marker in many situations, particularly when parathyroid disorders, vitamin D deficiency, kidney disease, or critical illness is involved. Because ionized calcium is not influenced by albumin levels, it provides a truer picture of calcium status.
This test is recommended when evaluating suspected parathyroid gland disorders, vitamin D deficiency, malabsorption syndromes, or kidney conditions such as uraemia. It is also the preferred measurement in hospitalised or critically ill patients, where albumin levels may be abnormal and total calcium is harder to interpret.
What a high value can mean
Elevated ionized calcium (hypercalcaemia) may point to hyperparathyroidism, certain cancers, excess vitamin D, or other endocrine disorders. It can cause symptoms such as excessive thirst, frequent urination, nausea, bone pain, and confusion.
What a low value can mean
Low ionized calcium (hypocalcaemia) may suggest hypoparathyroidism, vitamin D deficiency, kidney disease, magnesium deficiency, or malabsorption. Symptoms include muscle cramps, numbness, tingling, and in severe cases, cardiac arrhythmias.
No fasting required. Special sample handling may be necessary -- follow any instructions from the laboratory. Bring valid ID.
Order your test
Choose your test and pay online. Your lab referral is created straight away.
Give your sample
Visit any of our partner sampling locations. No appointment needed at most of them.
The lab analyses it
Your sample is analysed at an accredited Swedish laboratory.
Get your results
Your values appear in your account with reference ranges and an explanation of each marker.
Total calcium includes both protein-bound and free forms. Ionized calcium measures only the free, active form, which is more clinically relevant because it directly affects bodily functions.
If your albumin is low, total calcium may appear falsely low. Ionized calcium gives a more accurate reading in these situations, as well as in critically ill patients.
Yes. Changes in blood pH alter the binding of calcium to albumin. Acidosis increases ionized calcium, while alkalosis decreases it.