Hypercalcemia: Causes, Symptoms, and What You Need to Know
Hypercalcemia is a medical condition characterized by abnormally high levels of calcium in the bloodstream. In adults, this typically refers to serum calcium levels exceeding 2.75 mmol/L. While calcium plays a vital role in bone health, muscle function, nerve signaling, and blood clotting, excessive amounts can disrupt normal bodily functions and lead to serious complications if left untreated.
Common Causes of Hypercalcemia
Several underlying conditions and medications can 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 reduced calcium excretion by the kidneys.
Other Key Contributing Factors Include:
- Malignancies with bone metastasis – Cancers such as breast, lung, or multiple myeloma can spread to the bones, causing calcium to leach into the bloodstream.
- Granulomatous diseases – Conditions like sarcoidosis or tuberculosis trigger immune cells that produce excess active vitamin D, enhancing calcium absorption from the gut.
- Medication-induced hypercalcemia – Long-term use of thiazide diuretics or lithium therapy for bipolar disorder may interfere with calcium regulation.
- Vitamin D toxicity – Over-supplementation can lead to excessive intestinal calcium absorption.
Recognizing the Symptoms
The signs of hypercalcemia vary depending on severity and how quickly calcium levels rise. Mild cases may be asymptomatic, often discovered during routine blood tests. However, more pronounced elevations can affect multiple organ systems.
Gastrointestinal and Renal Effects
Patients may experience loss of appetite, nausea, vomiting, constipation, and abdominal discomfort. Increased calcium load forces the kidneys to work harder, resulting in polyuria (excessive urination) and impaired urine concentration. Over time, this raises the risk of kidney stones and potential long-term kidney damage.
Nervous System Involvement
Elevated calcium can cross the blood-brain barrier and impact brain function. Neurological symptoms may include mental fogginess, memory problems, difficulty concentrating, drowsiness, confusion, and disorientation. In severe cases, individuals might develop hallucinations, seizures, or even fall into a coma.
Cardiovascular and Muscular Symptoms
Hypercalcemia can also influence heart rhythm, potentially causing bradycardia (slow heart rate) or abnormal electrical activity visible on an ECG. Muscle weakness and fatigue are commonly reported, further reducing quality of life.
Diagnosis and Management
Early detection through blood testing—including serum calcium, PTH, vitamin D levels, and kidney function—is crucial. Imaging studies may be used to identify tumors or bone lesions. Treatment focuses on addressing the root cause, rehydration with intravenous fluids, and, in acute cases, administering bisphosphonates or corticosteroids to lower calcium rapidly.
For chronic or mild hypercalcemia, lifestyle adjustments such as staying well-hydrated, limiting calcium-rich supplements, and regular monitoring can help prevent complications. Always consult a healthcare provider if you're at risk or experiencing unexplained symptoms.