Calcium Blood Test
Feb 12, 2026
Calcium Blood Test
A calcium blood test measures the amount of calcium in your blood—essential for bone health, muscle contraction, nerve function, and heart rhythm, with both high (hypercalcemia) and low (hypocalcemia) levels potentially indicating serious underlying conditions that require investigation. Unlike many nutrients, blood calcium is tightly regulated, so abnormal levels usually signify a medical issue rather than simple dietary deficiency.
At Blood Test London, calcium testing costs from £245 with results in 2-3 days.
Understanding Calcium Testing
What We Measure
Test | What It Shows |
|---|---|
Total calcium | All calcium (bound + free) |
Corrected calcium | Adjusted for albumin levels |
Ionised calcium | "Free" active calcium (most accurate) |
Normal Ranges
Test | Normal Range |
|---|---|
Total calcium | 2.2-2.6 mmol/L |
Corrected calcium | 2.2-2.6 mmol/L |
Ionised calcium | 1.15-1.3 mmol/L |
Causes of Abnormal Calcium
High Calcium (Hypercalcemia)
Cause | Notes |
|---|---|
Primary hyperparathyroidism | Most common cause—parathyroid gland overactive |
Cancer | Some cancers release calcium from bones |
Excessive vitamin D | Over-supplementation |
Certain medications | Thiazide diuretics, lithium |
Dehydration | Concentrated blood |
Sarcoidosis | Inflammatory condition |
Low Calcium (Hypocalcemia)
Cause | Notes |
|---|---|
Vitamin D deficiency | Common, easily treated |
Hypoparathyroidism | Underactive parathyroid |
Kidney disease | Affects calcium regulation |
Magnesium deficiency | Impairs calcium regulation |
Certain medications | Some cause calcium loss |
Pancreatitis | Acute illness effect |
Symptoms of Calcium Imbalance
High Calcium Symptoms
Excessive thirst and urination
Constipation
Nausea and vomiting
Confusion and fatigue
Muscle weakness
Bone pain
Kidney stones
Heart rhythm issues
Low Calcium Symptoms
Muscle cramps and spasms
Tingling (fingers, toes, lips)
Numbness
Fatigue
Brittle nails
Confusion
Abnormal heart rhythm
Related Tests
When calcium is abnormal, we often also check:
Test | Why |
|---|---|
PTH (parathyroid hormone) | Regulates calcium—key to diagnosis |
Vitamin D | Affects calcium absorption |
Phosphate | Inversely related to calcium |
Magnesium | Required for calcium regulation |
Kidney function | Affects calcium handling |
Albumin | Low albumin affects total calcium |
Bone Health and Calcium
Blood calcium doesn't reflect bone calcium stores. You can have:
Normal blood calcium + osteoporosis
Normal blood calcium + calcium deficiency in diet
For bone health assessment:
DEXA scan (bone density)
Vitamin D levels
PTH if calcium abnormal
Book Your Calcium Test
Price: From £245
Results: 2-3 days
Doctor review: A doctor always reviews every result
Fasting required: No (but morning preferred)
Phone: 020 3951 3429
FAQ
Does normal calcium mean my bones are healthy?
Not necessarily—blood calcium is tightly regulated regardless of bone health. Bone density scanning assesses bone health directly.
Should I stop calcium supplements before testing?
Ideally, maintain your normal routine for accurate results. If levels are high, your doctor may ask you to stop temporarily and retest.
What if my calcium is slightly high?
Even mildly elevated calcium needs investigation, as primary hyperparathyroidism is common and treatable.
Blood Test London by The Wellness. Calcium testing from £245, results in 2-3 days.