Calcium Disorders of Aging

It is important to recognize calcium disorders when they present in older patients. Hypercalcemia, or elevated calcium levels, is seen more commonly than hypocalcemia, or low calcium levels. The most common symptoms of individuals with hypercalcemia include drowsiness, fatigue, muscle weakness, high blood pressure, constipation, and dehydration. Sometimes, individuals can present to the hospital in a coma. The most common cause of elevated calcium levels in people who present in an outpatient clinic is primary hyperparathyroidism, a condition where the hormone that regulates the body's calcium level, the parathyroid hormone, is overproduced. This overproduction leads to high levels of calcium. Long-term complications include kidney stones, osteoporosis, high blood pressure, and (with very elevated calcium levels) life-threatening illness. This disorder can be corrected with the surgical removal of the parathyroid gland.

A serious form of hypercalcemia is seen in patients who have a history of cancer. When cancer spreads to the bones, this alters the body's regulation of calcium. More than 95% of the calcium in our body is stored in our bones and can be released in excess when metastasis from certain cancers occurs.

A less common form of hypercalcemia is due to excess consumption of calcium, Vitamin A, or Vitamin D in the diet. In the past, many patients used antacids and baking soda to relieve heartburn. Most older antacids contain high levels of calcium. Consuming very large amounts of these antacids can lead to hypercalcemia. Newer medications for heart-burn and stomach ulcers do not contain large amounts of calcium.

The most common symptoms of hypocalcemia are mental confusion, muscle spasms, tingling, and seizures. Some of the causes of low calcium include prior surgical removal of the parathyroid glands, renal failure, and poor dietary intake of calcium and Vitamin D. Vitamin D deficiency is a very common and treatable cause of hypocalcemia. Vitamin D is derived from the diet and is converted to the active form by several organ systems. The first step in this transformation is initiated in the skin. In older adults, the skin becomes less efficient in converting the substrates of Vitamin D to its active form. As individuals live farther away from the equator and have limited sunlight exposure, their bodies do not produce adequate amounts of Vitamin D. These persons also tend to wear more clothing in cooler climates, blocking the effects of sunlight in converting Vitamin D to its active form. Vitamin D is further modified by the liver and kidney, so diseases of these organs can contribute to Vitamin D deficiency. Individuals who have liver failure, difficulty in absorbing fats, and/or chronic kidney disease are at risk for Vitamin D deficiency. Not only will Vitamin D deficiency cause low calcium levels, but also long-term deficiency leads to loss of bone or osteoporosis. Patients with osteoporosis should take in approximately 800 international units [Page 86]of Vitamin D per day. This will not only maintain calcium levels and but also prevent fractures.