Hypercalcaemia (high calcium): symptoms, causes and treatment

Many people with a mildly raised calcium have no symptoms and are only found when blood tests are done for another reason. The NHS says this about hyperparathyroidism, the most common cause, and NICE CKS notes that symptoms and signs are often non-specific and relate to how high the calcium is and how quickly it has risen.

CKS lists the clinical features that should prompt consideration of hypercalcaemia. They can be grouped by the part of the body involved, though most people have only one or two.

• Thirst and passing more urine than usual

• Constipation, nausea, vomiting, abdominal pain, loss of appetite and weight loss

• Tiredness, low mood, depression, memory problems and confusion

• Bone pain and osteoporosis

• Kidney stones (renal colic) or reduced kidney function

Treatment depends on how high the calcium is and what is causing it. CKS advises emergency hospital admission for severe hypercalcaemia or severe symptoms, and emergency or urgent referral for moderate hypercalcaemia. For milder cases the calcium is repeated to confirm the diagnosis and the cause is then investigated.

When a medicine is responsible, CKS says to reduce or stop it and monitor the response. Calcium levels usually return to normal after a thiazide diuretic is stopped, unless there is underlying primary hyperparathyroidism, and the effects of lithium are typically reversed when it is withdrawn.

For primary hyperparathyroidism, the NHS says that if a growth on the parathyroid glands is the cause you will be offered surgery to remove part or all of the glands, and that if you do not want surgery or it is not suitable, a specialist may offer medicine to lower calcium. NICE guidance NG132 says people with confirmed primary hyperparathyroidism should be referred to a surgeon with parathyroid expertise if they have symptoms such as thirst, frequent urination or constipation, kidney stones, fragility fractures or osteoporosis, or an adjusted calcium of 2.85 mmol/L or above, and that cinacalcet can be considered if surgery has been unsuccessful, is unsuitable or has been declined and calcium remains high enough.

CKS says surgery for most cases of symptomatic primary hyperparathyroidism is curative, with cure rates over 95% in people who have a single adenoma and recurrence rates under 2%.

Where the cause is cancer, CKS says care involves the person’s treating specialist, oncologist or palliative care team, with emergency or urgent referral for prompt treatment if hypercalcaemia is severe or moderate or there are symptoms.

Dehydration commonly goes with hypercalcaemia and can push calcium up further, which is one reason it is taken seriously. CKS describes assessing hydration as part of the examination.

CKS says there are many possible causes, the two most common being primary hyperparathyroidism and malignancy, which together account for 90% of cases. More than one cause can co-exist.

Primary hyperparathyroidism is the commonest overall. It is due to excessive parathyroid hormone (PTH) from the parathyroid glands in the neck, and a single non-cancerous growth (adenoma) is the cause in about 85% of cases. Cancer is the second most common cause overall but the most common in hospital inpatients; CKS says it is often a late finding in advanced cancer and that the underlying cancer is often already known.

The NHS explains that hyperparathyroidism happens when the body makes too much PTH, which affects the amount of calcium in the blood, and that calcium helps keep bones and teeth healthy.

Calcium is carried in the blood partly bound to a protein called albumin, so laboratories report an adjusted (or corrected) calcium that allows for the albumin level. CKS defines hypercalcaemia as an adjusted serum calcium of 2.6 mmol/L or higher on two occasions.

It is a finding rather than a disease in itself, which is why the next step is always to find the cause. Parathyroid hormone (PTH) is a key test, measured together with calcium: CKS says PTH is typically raised in primary and tertiary hyperparathyroidism, and suppressed or undetectable in hypercalcaemia caused by cancer or other non-PTH causes.

The calcium is confirmed with a blood test adjusted for albumin, and repeated if the person is well and the level is only mildly or moderately raised. CKS says assessment includes asking about symptoms, other conditions, family history of hypercalcaemia, and all medicines, supplements and over-the-counter preparations.

The doctor also looks at hydration, checks for cognitive change and examines for signs of an underlying cause. In primary hyperparathyroidism the calcium rise is usually mild, stable or slowly progressive over years, whereas cancer-related hypercalcaemia is often rapid in onset, severe and associated with other symptoms.

The NHS says hyperparathyroidism can be diagnosed by blood and urine tests, and that scans such as ultrasound, X-rays and bone density scans may then be recommended to check general health and plan treatment.

Hypercalcaemia that is severe, or that comes with severe symptoms, is an emergency. CKS advises emergency hospital admission in those situations and urgent, usually same-day, referral if calcium is moderately raised.

Because symptoms can be non-specific, the severity of the symptoms is what counts, not just the number on the blood test. CKS lists confusion and memory problems among the features and notes that a person with advanced cancer can deteriorate rapidly. If you have a known high calcium and are getting worse, call NHS 111 or, if you are very unwell, 999.

If you have been told your calcium is mildly raised, see your GP to arrange the repeat test and follow-up rather than waiting for symptoms to appear. The NHS says treatment is usually needed for hyperparathyroidism, so you should get checked if you have symptoms, and that treatment can stop it getting worse and prevent complications.

The NHS says untreated hyperparathyroidism can lead to osteoporosis, kidney stones and high blood pressure, which can increase the risk of heart disease and stroke.

CKS says prognosis depends on the cause: where the cause is benign and treatable the outlook is good, and calcium that was raised by a medicine often normalises a few weeks after the medicine is withdrawn. After specialist assessment, primary care follow-up includes monitoring calcium, kidney function, bone density and kidney imaging as advised.

The NHS says not to make changes to your diet to try to lower your calcium unless your specialist has told you to, because a change in your usual diet could make symptoms worse or cause more serious problems. CKS says excessive calcium supplements, vitamin D and vitamin A can themselves cause hypercalcaemia, so tell your doctor about everything you take.

The UK sources we read do not give specific guidance on hypercalcaemia in pregnancy. If you are pregnant or planning pregnancy and have been told your calcium is high, this needs to be discussed with your doctor.

On the NHS, a raised calcium is usually found by a GP or hospital blood test. CKS advises arranging referral to an endocrinologist if primary hyperparathyroidism, familial hypocalciuric hypercalcaemia or another hormone cause is suspected, to the appropriate specialist if another cause is suspected, and to hospital urgently if the calcium is moderately or severely raised.

Parathyroid UK, a charity, provides support and information for people living with parathyroid conditions. The NHS signposts it on its hyperparathyroidism page.