Hypercalcaemia is a condition characterized by high levels of calcium in the blood. Calcium is crucial for many bodily functions, including muscle contraction, nerve transmission, and bone health. However, when blood calcium levels become too elevated, it can lead to various symptoms and complications. Understanding the causes, recognizing the symptoms, and managing hypercalcaemia effectively are essential for preventing long-term health issues.
Causes of Hypercalcaemia
Hypercalcaemia can result from several conditions, ranging from benign to severe. Some of the most common causes include:
1. Primary Hyperparathyroidism
- The parathyroid glands (located in the neck) regulate calcium levels by releasing parathyroid hormone (PTH). In primary hyperparathyroidism, one or more of these glands become overactive, producing too much PTH, which leads to increased calcium release from bones into the bloodstream.
- This is the most common cause of hypercalcaemia in non-hospitalized individuals.
2. Malignancy
- Certain cancers, especially those that involve the bones (like multiple myeloma and breast cancer) or lungs (such as non-small cell lung cancer), can cause hypercalcaemia.
- Cancers can release parathyroid hormone-related protein (PTHrP) or directly invade bone, leading to elevated calcium levels.
3. Vitamin D Toxicity
- Excessive vitamin D intake can increase calcium absorption from the intestines, leading to high calcium levels. This is usually seen with excessive use of supplements or certain medications containing vitamin D.
4. Kidney Disease
- In advanced chronic kidney disease (CKD), the kidneys lose their ability to filter calcium efficiently, leading to secondary hyperparathyroidism. This condition can cause an increase in calcium in the blood.
5. Granulomatous Diseases
- Diseases like sarcoidosis or tuberculosis can increase calcium levels due to the production of excess calcitriol (the active form of vitamin D), which boosts calcium absorption in the intestines.
6. Medications
- Certain medications, such as thiazide diuretics, lithium, and calcium-containing antacids, can increase calcium levels in the blood.
7. Endocrine Disorders
- Thyroid diseases, particularly hyperthyroidism, can lead to elevated calcium levels. The thyroid hormone has an indirect effect on bone resorption, releasing more calcium into the bloodstream.
Symptoms of Hypercalcaemia
Mild cases of hypercalcaemia might not cause noticeable symptoms, but when calcium levels rise significantly, symptoms can appear. These include:
- Fatigue or weakness
- Frequent urination (due to calcium’s effects on kidney function)
- Thirst or dehydration
- Nausea and vomiting
- Constipation
- Abdominal pain
- Bone pain or fractures (due to calcium being leached from bones)
- Confusion or cognitive changes
- Muscle weakness or cramps
- Heart arrhythmias or palpitations
In severe cases, hypercalcaemia can lead to:
- Coma
- Kidney failure
- Cardiac arrhythmias, which can be life-threatening
Diagnosis of Hypercalcaemia
To diagnose hypercalcaemia, doctors will typically perform several tests:
- Blood Tests:
- Total Calcium Level: Measures the overall calcium concentration in the blood. It includes both free (ionized) and bound calcium.
- Ionized Calcium: This test measures the active form of calcium, which is usually more accurate in assessing hypercalcaemia.
- Parathyroid Hormone (PTH): Elevated PTH levels can indicate primary hyperparathyroidism.
- Vitamin D Levels: Checking vitamin D levels helps determine whether toxicity or deficiency is contributing to elevated calcium levels.
- Creatinine and BUN: These tests assess kidney function, as kidney disease can contribute to hypercalcaemia.
- Imaging Tests:
- X-rays or Bone Scans: To detect bone abnormalities or fractures, particularly in cases where malignancy is suspected.
- Ultrasound or CT Scans: To detect parathyroid adenomas (benign tumors of the parathyroid gland) or cancerous growths that could be causing hypercalcaemia.
- Urine Tests:
- 24-hour urine calcium excretion: This can help determine if the kidneys are properly excreting calcium, which is important in diagnosing hypercalcaemia due to hyperparathyroidism or malignancy.
Treatment of Hypercalcaemia
Treatment depends on the underlying cause of hypercalcaemia, as well as the severity of the condition.
1. Rehydration
- Intravenous fluids (IV) are often given to patients to rehydrate and help dilute the calcium levels in the blood. This also promotes calcium excretion by the kidneys.
2. Medications
- Bisphosphonates (e.g., zoledronic acid) or denosumab: These medications help reduce bone resorption and lower calcium levels in patients with cancer-related hypercalcaemia.
- Calcitonin: This hormone helps lower calcium levels by inhibiting bone resorption and increasing calcium excretion by the kidneys. It’s often used in acute situations.
- Corticosteroids: For hypercalcaemia caused by granulomatous diseases like sarcoidosis or tuberculosis, steroids can reduce calcium absorption and levels.
- Diuretics: Loop diuretics (e.g., furosemide) are sometimes used after adequate rehydration to help the kidneys excrete excess calcium.
3. Treating the Underlying Condition
- Surgery: If hypercalcaemia is caused by a parathyroid adenoma or hyperplasia, surgical removal of the affected parathyroid gland may be required.
- Cancer Treatment: In cases where malignancy is the cause, treatment of the cancer (e.g., chemotherapy, radiation, or surgery) can help reduce hypercalcaemia.
- Vitamin D or Calcium Management: For vitamin D toxicity or excess calcium intake, reducing or stopping supplements can help correct the imbalance.
4. Dialysis
In severe cases, particularly when there is kidney failure, dialysis may be needed to remove excess calcium from the bloodstream.
Prognosis and Prevention
The prognosis for hypercalcaemia depends on the underlying cause and how promptly it is treated. For example:
- In cases of primary hyperparathyroidism, surgery often leads to a complete recovery.
- Cancer-related hypercalcaemia requires treating the cancer, which can be more challenging but may lead to improved outcomes with appropriate therapies.
Preventing hypercalcaemia involves managing conditions that predispose individuals to the condition, such as monitoring calcium and vitamin D intake, treating kidney disease, and keeping an eye on parathyroid function, especially in individuals with risk factors for hyperparathyroidism.
Conclusion
Hypercalcaemia is a potentially serious condition that can cause a range of symptoms from mild fatigue to life-threatening complications. Early detection, a thorough understanding of its causes, and prompt treatment are crucial for preventing long-term damage. By addressing the underlying causes—whether it’s primary hyperparathyroidism, malignancy, or medication-related—the condition can often be effectively managed and treated.