Hypercalcemia

Hypercalcemia refers to an increase in blood calcium concentration above the normal limit. Under normal conditions, blood calcium levels range from 8.8 to 10.5 mg/dL.

Calcium is one of the body's electrolytes. It is mainly found in the bones and plays a role in several body processes, including bone formation and maintenance, muscle contraction, neurotransmission, hormone secretion, and the regulation of heart rate and blood pressure, among others.

The body regulates calcium levels in the blood through vitamin D and parathyroid hormone, which help maintain a balance between calcium in the bones, dietary intake, and urinary loss. Excess calcium can affect the bones, kidneys, heart, digestive system, and brain

Symptoms

Mild hypercalcemia typically does not present symptoms. In more severe cases, the following may occur:

• Digestive symptoms:
• Abdominal pain
• Nausea, vomiting
• Constipation
• Osteomuscular symptoms:
• Bone pain
• Muscle weakness
• Renal symptoms:
• Frequent urination
• Increased thirst
• Lower back pain
• Neurological symptoms:
• Fatigue, lethargy
• Headache
• Difficulty concentrating
• Decreased reflexes
• Irritability, depression
• Confusion
• In very severe cases, delusions or hallucinations
• Cardiac symptoms (very rare):
• Palpitations
• Arrhythmias

Causes

Possible causes of hypercalcemia include:

• Hyperparathyroidism: One or more parathyroid glands produce excessive parathyroid hormone due to enlargement or a tumor. This hormone overproduction mobilizes calcium from bones into the bloodstream, increases intestinal absorption, and reduces renal excretion. It is the most common cause of hypercalcemia.
• Cancer (tumor-related or malignant hypercalcemia): In some types of cancer, tumors secrete a peptide similar to parathyroid hormone, increasing calcium concentration in the blood. Additionally, cancers that metastasize to the bone cause bone resorption, also releasing calcium. This is a common paraneoplastic syndrome in lung, kidney, ovarian, breast, prostate, and bone marrow cancers (multiple myeloma).
• Excessive calcium intake: Consuming too much dietary calcium or calcium-based antacids.
• Excessive and prolonged vitamin D intake: Too much vitamin D increases intestinal calcium absorption.
• Bone disorders: Diseases causing bone resorption, such as severe hyperthyroidism or Paget’s disease, release calcium into the blood, potentially causing hypercalcemia.
• Granulomatous disorders that increase vitamin D levels, such as sarcoidosis, tuberculosis, or leprosy.
• Medications that increase parathyroid hormone secretion, such as lithium and diuretics.
• Inactivity: Prolonged immobilization causes bones to lose strength and release calcium into the bloodstream.
• Severe dehydration: Loss of water in the blood causes an increase in calcium concentration.
• Familial hypocalciuric hypercalcemia: A hereditary genetic disorder in which the parathyroid glands secrete excess parathyroid hormone. It causes moderate, typically asymptomatic hypercalcemia.

Risk Factors

Factors that increase the likelihood of developing hypercalcemia include:

• Use of calcium or vitamin D supplements
• Hospitalization, bed rest, paralysis, or other conditions involving prolonged immobility
• Use of medications associated with hypercalcemia
• Presence of diseases or disorders that raise calcium or vitamin D levels

Complications

Severe or prolonged hypercalcemia can have serious consequences for the body. Neurological involvement can progress to dementia and potentially life-threatening coma. Excess calcium in the kidneys often leads to kidney stones and, in some cases, kidney failure. While this failure often improves with treatment, excessive calcium accumulation may cause irreversible kidney damage. Persistent digestive symptoms may also lead to peptic ulcers and pancreatitis. Additionally, bone weakening due to hypercalcemia may result in osteoporosis, a condition where fragile bones cause frequent fractures.

Prevention

Most causes of hypercalcemia cannot be prevented, but measures can be taken to avoid diet-related hypercalcemia, such as staying well hydrated and avoiding excessive intake of calcium or vitamin D supplements. Periodic blood tests are also recommended to monitor calcium levels.

Which doctor treats hypercalcemia?

Hypercalcemia is diagnosed and treated in the endocrinology unit.