Hypercalcemia, also spelled hypercalcaemia, is a high calcium (Ca2+) level in the blood serum. The normal range is 2.1–2.6 mmol/L (8.8–10.7 mg/dL, 4.3–5.2 mEq/L), with levels greater than 2.6 mmol/L defined as hypercalcemia. Those with a mild increase that has developed slowly typically have no symptoms. In those with greater levels or rapid onset, symptoms may include abdominal pain, bone pain, confusion, depression, weakness, kidney stones or an abnormal heart rhythm including cardiac arrest.Most outpatient cases are due to primary hyperparathyroidism and inpatient cases due to cancer. Other causes of hypercalcemia include sarcoidosis, tuberculosis, Paget disease, multiple endocrine neoplasia (MEN), vitamin D toxicity, familial hypocalciuric hypercalcaemia and certain medications such as lithium and hydrochlorothiazide. Diagnosis should generally include either a corrected calcium or ionized calcium level and be confirmed after a week. Specific changes, such as a shortened QT interval and prolonged PR interval, may be seen on an electrocardiogram (ECG).Treatment may include intravenous fluids, furosemide, calcitonin, intravenous bisphosphonate, in addition to treating the underlying cause. The evidence for furosemide use, however, is poor. In those with very high levels, hospitalization may be required. Haemodialysis may be used in those who do not respond to other treatments. In those with vitamin D toxicity, steroids may be useful. Hypercalcemia is relatively common. Primary hyperparathyroidism occurs in 1–7 per 1,000 people, and hypercalcaemia occurs in about 2.7% of those with cancer. Signs and symptoms
The neuromuscular symptoms of hypercalcaemia are caused by a negative bathmotropic effect due to the increased interaction of calcium with sodium channels.
There is, however, controversy around the usefulness of corrected calcium as it may be no better than total calcium.Once calcium is confirmed to be elevated, a detailed history taken from the subject, including review of medications, any vitamin supplementations, herbal preparations, and previous calcium values. Chronic elevation of calcium with absent or mild symptoms often points to primary hyperparathyroidism or Familial hypocalciuric hypercalcemia. For those who has underlying malignancy, the cancers may be sufficiently severe to show up in history and examination to point towards the diagnosis with little laboratory investigations.If detailed history and examination does not narrow down the differential diagnoses, further laboratory investigations are performed. Intact PTH (iPTH, biologically active parathyroid hormone molecules) is measured with immunoradiometric or immunochemoluminescent assay. Elevated (or high-normal) iPTH with high urine calcium/creatinine ratio (more than 0.03) is suggestive of primary hyperparathyroidism, usually accompanied by low serum phosphate. High iPTH with low urine calcium/creatinine ratio is suggestive of familial hypocalciuric hypercalcemia. Low iPTH should be followed up with Parathyroid hormone-related protein (PTHrP) measurements (though not available in all labs). Elevated PTHrP is suggestive of malignancy. Normal PTHrP is suggestive of multiple myeloma, vitamin A excess, milk-alkali syndrome, thyrotoxicosis, and immobilisation. Elevated Calcitriol is suggestive of lymphoma, sarcoidosis, granulomatous disorders, and excessive calcitriol intake. Elevated calcifediol is suggestive of vitamin D or excessive calcifediol intake.The normal range is 2.1–2.6 mmol/L (8.8–10.7 mg/dL, 4.3–5.2 mEq/L), with levels greater than 2.6 mmol/L defined as hypercalcaemia.