Is my calcium level high?
Yes, if your adjusted calcium is 2.6 mmol/L or more. Below 3.0 it often causes no symptoms. What matters more is why. After a repeat test, a PTH test tells your GP where to look.
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Is my calcium level high?
Yes, if your adjusted calcium is 2.6 mmol/L or more. NICE counts 2.6 or above as raised. Labs such as Oxford give a normal range of 2.20 to 2.60.
Read the adjusted line, not the raw one. Some calcium sticks to albumin, a blood protein, and that part isn’t active. Adjusting gives a truer figure.
More in our calcium blood test guide.
- Below 2.6 mmol/LNot high. Most labs call 2.20 to 2.60 normal.
- 2.6 to just under 3 mmol/LHigh. Often no symptoms, not usually urgent.
- 3 up to 3.5 mmol/LPrompt treatment is usually needed.
- Above 3.5 mmol/LNeeds urgent treatment.
Sources: NICE NG132; Oxford University Hospitals; Society for Endocrinology
Slightly high, say 2.7, and you feel fine? Below 3.0, high calcium often causes no symptoms and doesn’t usually need urgent treatment.
One result isn’t the full story. Calcium can shift with changes in albumin or in how acidic your blood is. So NICE says to repeat the test at least once.
Ask your GP when your repeat test should be.
What causes high calcium levels?
Two causes explain 9 in 10 cases: overactive parathyroid glands, or cancer. The gland problem is usually a growth that isn’t cancer.
Your parathyroid glands are small glands in your neck. They make a hormone called PTH (parathyroid hormone). Too much PTH can affect the calcium in your blood.
| Cause | In plain words |
|---|---|
| Overactive parathyroid glands (primary hyperparathyroidism) | A growth on a gland in your neck, not a cancer, makes too much PTH. |
| Cancer | The other main cause. NICE says look for it if PTH comes back below its range. |
| Water tablets (thiazides) | Such as bendroflumethiazide, for high blood pressure or fluid build-up. |
| Lithium | A medicine for mood disorders such as bipolar disorder. |
| Too much vitamin D | Taking too many vitamin D supplements over a long time. |
| Overactive thyroid (thyrotoxicosis) | A thyroid gland making too much hormone. |
| Long spells without moving (immobilisation) | Being unable to move around for a long time. |
Sources: Society for Endocrinology; NHS: hyperparathyroidism; NICE NG132; NHS: bendroflumethiazide; NHS: lithium; NHS: vitamin D
Take lithium or a water tablet? Never stop or change a prescribed medicine without your prescriber. Tell your GP everything you take, supplements included.
On vitamin D? The NHS says adults and children aged 11 to 17 shouldn’t take more than 100 micrograms (4,000 IU) a day. See can you take too much vitamin D.
Wondering if it’s something you ate? The NHS says don’t change your diet to lower calcium unless your specialist tells you to.
What tests come next?
The test that points the way is PTH. NICE says to measure it once your calcium is 2.6 or more on two separate tests.
Your GP may check it from 2.5 on two tests, if they suspect overactive parathyroid glands.
What usually happens after a high calcium result
- 1
Repeat calcium
At least once, if the first result was 2.6 or more.
- 2
PTH test
Taken at any time of day, with calcium checked at the same time.
- 3
Read together
PTH above the middle of its range, if overactive glands are suspected, or below the middle with calcium of 2.6 or more: specialist advice. Below its range: look for other causes.
- 4
Specialist checks
May include vitamin D, a urine test, kidney checks and a bone scan.
Sources: NICE NG132; NICE NG132 rationale
Think of calcium as the warmth of a room and PTH as the heating. A hot room with the heating still on points to the glands.
A hot room with the heating off means the heat is coming from somewhere else. That’s when NICE says to look for other causes, including cancer.
Ask your GP whether you need a PTH test, and when.
What are the symptoms of high calcium?
Often there are none. Many people with overactive parathyroid glands have no, or very mild, symptoms. They find out from a test done for something else.
When there are symptoms, the NHS lists these for overactive parathyroid glands:
- tiredness and poor sleep
- joint and bone pain
- muscle weakness, spasms and tremors (shaking you can’t control)
- feeling and being sick, and loss of appetite
- constipation and tummy pain
- feeling thirsty all the time and peeing more than usual
- low mood and depression
- problems with memory and concentration
Calcium that is very high can also cause confusion.
Write down any symptoms and when they started. Take the list to your appointment.
How is high calcium treated?
It depends on the cause and how high it is. Above 3.5, calcium needs urgent treatment.
For overactive parathyroid glands, you’ll be referred to a specialist. If a growth is the cause, you’ll be offered surgery to remove the glands where the growth is. If you don’t want surgery, or it isn’t suitable, a specialist may offer medicine to help lower your calcium.
Once overactive parathyroid glands are confirmed, NICE advises referral to a surgeon if you have symptoms. These include thirst, a kidney stone, thin bones or a bone broken in a minor fall. Calcium of 2.85 or more also counts.
Left untreated, overactive parathyroid glands can lead to thin bones, kidney stones and high blood pressure. See bone health blood results and kidney function tests.
What to do after a high calcium result
- Ask your GP to repeat your calcium test if it was 2.6 or more.
- Ask whether you need a PTH test once two results are high.
- Write down symptoms such as thirst, peeing more than usual or constipation.
- List every medicine and supplement you take, including vitamin D, water tablets and lithium.
- Adults shouldn’t take more than 100 micrograms (4,000 IU) of vitamin D a day unless a doctor advises it.
- Don’t change your diet to lower calcium unless your specialist tells you to.
Sources: NICE NG132; NHS: hyperparathyroidism; NHS: vitamin D
When to speak to a GP
- Your adjusted calcium is 2.6 or more, or 2.5 or more with signs such as thirst or a kidney stone. NICE advises repeating the test.
- You’re thirsty all the time, peeing a lot or constipated, or you have thin bones, a kidney stone or a bone broken in a minor fall. NICE says to check your calcium.
- You think you might have overactive parathyroid glands. The NHS says see a GP.
- You’ve been told your calcium is above 3.5. It needs urgent treatment, so get medical advice straight away.
Go to A&E or call 999 if someone suddenly becomes confused.
Calcium can shift with your albumin level. See our albumin blood test guide.