In hypercalcemia, the blood calcium level is above what it should be. The mineral calcium is important for bone health, muscle contraction, nerve transmission, and blood clotting, among other functions in the body. If calcium levels are too high, kidney stones, bone loss, heart rhythm disturbances, and confusion can occur. Hypercalcemia can be caused by various factors, such as overactive parathyroid glands, certain cancers, medications, or vitamin D supplements. Medications, surgery, or lifestyle changes may be used to treat hypercalcemia, which is diagnosed through blood tests, urine tests, or imaging tests.
The main regulator of calcium in the blood is the parathyroid hormone (PTH), which is produced by four small glands behind the thyroid gland in the neck. By stimulating the release of calcium from bones, absorption of calcium from the intestines, and retention of calcium by the kidneys, PTH increases the calcium level in the blood. In addition to PTH, calcitonin, which is produced by the thyroid gland, affects calcium levels by inhibiting PTH's action. Vitamin D also plays a role in calcium balance, as it aids the body in absorbing calcium from food.
Hypercalcemia occurs when there is an imbalance between the production and the removal of calcium in the blood. There are two main types of hypercalcemia: primary and secondary.
As a result of a benign tumor (adenoma), an enlargement (hyperplasia) or cancer (carcinoma) of one or more of the parathyroid glands, primary hypercalcemia occurs. The overproduction of PTH in these conditions leads to high blood calcium levels. Primary hyperparathyroidism is also known as this type of hypercalcemia.
Secondary hypercalcemia is caused by a problem outside the parathyroid glands, such as a disease or a medication that affects the calcium level in the blood. Some examples of these causes are:
In particular, cancers of the bones, lungs, breasts, or kidneys can produce substances that mimic PTH or cause bone breakdown, which causes high levels of calcium in the blood to occur. This type of hypercalcemia is also known as hypercalcemia of malignancy.
Certain medications, such as thiazide diuretics, lithium, or vitamin A. These medications can increase the absorption or the retention of calcium by the body, which leads to high calcium levels in the blood.
Excessive intake of vitamin D or calcium supplements. These supplements can increase the absorption or the intake of calcium by the body, which leads to high calcium levels in the blood.
Certain diseases, such as sarcoidosis, tuberculosis, or fungal infections. These diseases can activate the production of vitamin D by the immune cells, which leads to high calcium levels in the blood.
Hypercalcemia's symptoms depend on the level and duration of calcium elevation in the blood. Mild hypercalcemia may not cause any symptoms and can be detected by routine blood tests. There are a number of symptoms associated with moderate to severe hypercalcemia, including:
Kidneys: Hypercalcemia can cause dehydration, increased thirst and urination, kidney stones, and kidney failure.
Bones: Hypercalcemia can cause bone pain, fractures, and osteoporosis.
Muscles: Hypercalcemia can cause muscle weakness, cramps, and spasms.
Nerves: Hypercalcemia can cause numbness, tingling, and burning sensations in the hands and feet.
Brain: Hypercalcemia can cause confusion, memory loss, depression, and coma.
Heart: Hypercalcemia can cause high blood pressure, irregular heartbeat, and cardiac arrest.
The diagnosis of hypercalcemia is based on the measurement of the calcium level in the blood, which is usually done by a blood test. Blood calcium levels can be affected by other factors as well, such as albumin levels, a protein that binds calcium. It is therefore possible to diagnose hypercalcemia by measuring the ionized calcium level, which is calcium that is biologically active and is not bound to albumin. Total calcium levels in the blood should range from 8.5 to 10.2 milligrams per deciliter (mg/dL), while ionized calcium levels should range from 4.6 to 5.3 mg/dL.
To determine the cause of hypercalcemia, the doctor may also order other tests, such as:
Parathyroid hormone (PTH) level, which can help differentiate between primary and secondary hypercalcemia. A high PTH level indicates primary hypercalcemia, while a low or normal PTH level indicates secondary hypercalcemia.
Vitamin D level, which can help identify the source of vitamin D excess, such as supplements, medications, or diseases.
Urine calcium level, which can help assess the kidney function and the response to treatment.
Imaging tests, such as ultrasound, X-ray, CT scan, or MRI, which can help detect any tumors, stones, or abnormalities in the parathyroid glands, the kidneys, or the bones.
A person's treatment of hypercalcemia depends on his or her cause, severity, and symptoms. The main goals of the treatment are to lower the calcium level in the blood, to treat the underlying problem, and to prevent or manage any complications. Some possible treatments include:
In mild to moderate hypercalcemia, fluids and diuretics can help rehydrate the body, increase urine output, and flush out excess calcium from the kidneys.
Hypercalcemia can be treated with medications that can inhibit the production or action of PTH, reduce calcium absorption or release from bones, or treat infection or inflammation. Bisphosphonates, calcitonin, glucocorticoids, and antibiotics are examples of these medications.
It is usually reserved for severe hypercalcemia or kidney failure that does not respond to other treatments. Dialysis can remove excess calcium and other waste products from the blood.
An adenoma, a carcinoma, or cancer can cause excess PTH or calcium production. This is usually reserved for primary hypercalcemia that does not respond to other treatments.
There is no specific way to prevent hypercalcemia, as it can have many different causes. However, some general measures that may help reduce the risk or the severity of hypercalcemia are:
Regular medical checkups, especially if there is a family history of hypercalcemia or hyperparathyroidism, can help detect and treat any problems that may affect the calcium level in the blood, such as tumors, infections, or kidney disease.
Prevent or reduce hypercalcemia by avoiding or limiting the intake of calcium and vitamin D supplements, unless prescribed by your doctor.
When a patient has been diagnosed with a condition that can cause hypercalcemia, such as cancer, sarcoidosis, or tuberculosis, follow the doctor's instructions and take the prescribed medications. The parathyroid glands and kidneys can be managed or controlled this way to prevent complications.
