In otherwise healthy patients, hypocalcemia and hypercalcemia are relatively uncommon conditions. A healthy body is usually able to regulate the level of calcium in the bloodstream without any difficulty, though there are diseases that can cause calcium levels to rise or fall. Patients with certain disorders, such as parathyroid problems, renal failure, or some types of cancer, can experience either of these conditions, depending on the nature of the disease. The risk of both hypocalcemia and hypercalcemia is higher in elderly patients, and the incidence of hypocalcemia is higher in pediatric medicine, especially among newborns.
Problems with the parathyroid gland are rare, affecting only about 25 out of 100,000 patients, but they often lead to hypocalcemia and hypercalcemia. This gland is partially responsible for maintaining the balance of a number of minerals and enzymes, including calcium. The absence of hormones released from this gland, which most frequently occurs when the gland is removed during an operation on the thyroid gland, causes the bones to hold onto calcium rather than allowing some of it to remain in the bloodstream, resulting in hypocalcemia. A hyperactive parathyroid gland can cause the bones to lose too much calcium, resulting in the opposite condition, hypercalcemia.
Kidney disease and cancer of the kidneys can also lead to hypocalcemia and hypercalcemia. These diseases affect approximately 10% of the adult population, though the percentage of people with hypocalcemia or hypercalcemia as a result of these diseases is lower. Problems with the kidneys can lead to hypocalcemia and hypercalcemia because, if the kidneys do not function properly, they can allow too much calcium to leave the body through the urine or reabsorb too much of the mineral back into the body.
Hypocalcemia is uncommon in pediatrics, and hypercalcemia is rarely ever seen. Hypocalcemia is frequently seen in infants who are born too early or too small. Approximately 30% of infants born with a birth weight of less than 3.3 pounds (1,500 grams) and 89% of those born before the 32nd week of gestation have either very low concentrations or no calcium in the blood.
In geriatrics, the prevalence of both hypocalcemia and hypercalcemia are higher than is seen in the adult population. Though still uncommon, elderly patients are at higher risk of disorders that lead to elevated or depleted blood-calcium levels. Patients with any form of cancer are also more likely to develop hypocalcemia and hypercalcemia, which occurs in between 20% and 40% of cancer patients. Patients who have undergone surgery or an injury in which a bone has been damaged are at a great risk of developing hypocalcemia, as the injured bone needs additional calcium to repair itself.