Hypercalcemia: Understanding the Causes, Symptoms, and Health Implications

Hypercalcemia is a medical condition characterized by abnormally high levels of calcium in the bloodstream, typically defined as serum calcium exceeding 2.75 mmol/L in adults. While calcium is essential for bone health, nerve function, and muscle contraction, excessive amounts can disrupt normal physiological processes and lead to a range of systemic complications.

Common Causes of Hypercalcemia

Several underlying conditions and medications are known to contribute to elevated calcium levels. One of the most frequent causes is primary hyperparathyroidism, a disorder in which the parathyroid glands produce too much parathyroid hormone (PTH), leading to increased calcium release from bones and enhanced calcium reabsorption in the kidneys.

Other significant contributors include granulomatous diseases such as sarcoidosis and tuberculosis, in which activated immune cells produce excess calcitriol—the active form of vitamin D—resulting in heightened intestinal calcium absorption. Additionally, certain malignancies, particularly those with bone metastases like breast or lung cancer, can cause hypercalcemia through direct bone destruction or secretion of PTH-related peptides.

Medications That May Trigger High Calcium Levels

Pharmacological agents also play a role in the development of hypercalcemia. Long-term use of thiazide diuretics, commonly prescribed for hypertension, reduces calcium excretion in urine and may lead to accumulation over time. Similarly, lithium therapy, widely used in managing bipolar disorder, can alter parathyroid function and increase PTH secretion, thereby elevating serum calcium.

Clinical Symptoms and Systemic Effects

The manifestations of hypercalcemia vary widely depending on severity and onset speed. In mild cases, individuals may be asymptomatic, but as calcium levels rise, a constellation of symptoms emerges across multiple organ systems.

Gastrointestinal and Renal Symptoms

Patients often experience loss of appetite, nausea, and vomiting due to the effect of high calcium on gastrointestinal motility. Increased calcium filtration in the kidneys leads to polyuria (excessive urination) and impaired urine concentration, potentially resulting in dehydration and kidney damage over time. Chronic hypercalcemia also raises the risk of kidney stone formation due to elevated urinary calcium excretion.

Neurological and Cognitive Impact

Elevated calcium can significantly affect brain function. Common neurological symptoms include mental fogginess, memory impairment, and difficulty concentrating. As the condition progresses, patients may develop drowsiness, confusion, disorientation, and even stupor in severe cases. Some individuals report persistent dizziness and fatigue, which can interfere with daily activities and reduce overall quality of life.

Early recognition and management of hypercalcemia are crucial to prevent long-term complications. Diagnosis typically involves blood tests to measure serum calcium, PTH, vitamin D levels, and imaging studies when malignancy or granulomatous disease is suspected. Treatment focuses on addressing the root cause, hydration, and, in acute cases, intravenous bisphosphonates or corticosteroids depending on the etiology.