Hypercalcemia occurs when there are abnormally high levels of calcium in the blood. While calcium is vital for the body, an excessive amount can lead to various health concerns. Elevated levels signal a need for further investigation, as the condition can range from mild to severe depending on its underlying cause.
The Body’s Calcium Balance
Calcium is the most abundant mineral in the human body, with the vast majority stored in bones and teeth. Beyond its structural role, calcium facilitates communication between the brain and other body parts, supports muscle movement, blood clotting, and heart function. The body maintains calcium levels within a narrow range through a finely tuned regulatory system.
This regulation involves a complex interplay of hormones and organs, including the parathyroid glands, kidneys, and intestines. Parathyroid hormone (PTH), produced by four small glands in the neck, increases blood calcium by stimulating its release from bones, enhancing its reabsorption in the kidneys, and promoting vitamin D activation. Active vitamin D aids in absorbing calcium from food in the digestive tract. Calcitonin helps lower calcium levels by inhibiting its release from bones.
Recognizing the Signs
Symptoms of elevated calcium vary considerably, with mild cases often showing no noticeable signs. When symptoms appear, they often affect multiple body systems. Individuals may experience digestive issues like stomach upset, nausea, vomiting, or constipation. Increased thirst and frequent urination are common as kidneys work harder to filter excess calcium.
The musculoskeletal system can also be affected, leading to bone pain, muscle weakness, or muscle twitches. Over time, this can contribute to bone thinning. Neurological symptoms can include fatigue, confusion, drowsiness, and difficulty concentrating. Hypercalcemia may also be linked to changes in mood, such as depression or irritability.
Common Reasons for Elevated Calcium
The most frequent reason for elevated calcium levels is primary hyperparathyroidism. This condition arises when one or more of the four parathyroid glands become overactive, producing an excessive amount of parathyroid hormone. This excess hormone causes calcium to be pulled from bones and absorbed more effectively from the diet, leading to higher blood calcium. In most cases, primary hyperparathyroidism is caused by a benign growth on one of the parathyroid glands.
Malignancy, or cancer, represents another significant cause of hypercalcemia. Certain cancers, such as lung, breast, and some blood cancers, can directly raise calcium levels. This can occur if cancer spreads to the bones, causing calcium release, or if tumors produce substances that mimic parathyroid hormone, leading to increased calcium mobilization.
Certain medications can also contribute to elevated calcium. Thiazide diuretics, used for high blood pressure, can decrease calcium excretion by the kidneys. Lithium, a medication for bipolar disorder, may increase parathyroid hormone levels. Additionally, excessive intake of vitamin D or vitamin A supplements can lead to hypercalcemia, as these vitamins enhance calcium absorption.
Other medical conditions can also cause high calcium. Granulomatous diseases like sarcoidosis and tuberculosis can lead to increased production of active vitamin D, resulting in greater calcium absorption from the gut and bones. Prolonged immobility can cause bones to release calcium into the bloodstream. Severe dehydration concentrates the blood, which can also temporarily elevate calcium levels.
What Happens After a High Reading?
If a blood test reveals an elevated calcium level, further medical evaluation is important to determine the underlying cause. A healthcare professional will typically review medical history, conduct a physical examination, and inquire about any medications being taken. Additional blood tests are often ordered to measure specific hormone levels, such as parathyroid hormone (PTH) and vitamin D, to help pinpoint the reason for the high calcium.
These tests help distinguish between conditions where PTH levels are appropriately high (indicating a parathyroid issue) and those where PTH is suppressed or normal despite high calcium, suggesting other causes. Depending on the initial findings, imaging studies might be recommended to examine the parathyroid glands or to look for other potential sources of the calcium elevation. Treatment for hypercalcemia focuses on addressing the root cause of the imbalance.