Hypercalcemia (High Blood Calcium)
High blood calcium that can affect bones, kidneys, and the nervous system
Quick Facts
- Type: Metabolic finding
- Common causes: Overactive parathyroid glands, cancer
- Affects: Bones, kidneys, digestion, nerves
- Emergency: Very high calcium with confusion or collapse
Overview
Hypercalcemia means the level of calcium in the blood is higher than normal. Calcium is essential for healthy bones, nerves, muscles, and the heart, and the body carefully controls it using hormones, mainly from the parathyroid glands. When that control is disrupted, calcium can build up in the blood.
Mild hypercalcemia often causes no symptoms and is found on a routine blood test. Higher levels can affect many systems, causing the classic pattern sometimes described as "bones, stones, groans, and psychiatric moans" — bone aches, kidney stones, digestive upset, and changes in mood or thinking. Severe hypercalcemia is a medical emergency. The two most common causes are overactive parathyroid glands and cancer.
How quickly calcium rises matters as much as how high it is. A gradual, mild increase — as often happens with overactive parathyroid glands — may cause few or no symptoms for a long time. A rapid rise, more typical of cancer-related hypercalcemia, can quickly cause dehydration, confusion, and serious illness. Because mild cases are silent, hypercalcemia is frequently discovered by chance, which is one reason routine blood tests are valuable.
Common Causes
High blood calcium can result from several causes:
- Overactive parathyroid glands (hyperparathyroidism): The most common cause, in which one or more glands release too much hormone.
- Cancer: Some cancers raise calcium directly or by spreading to bone; this is the most common cause in hospitalized patients.
- Excess vitamin D or calcium intake: From high-dose supplements or some medical conditions.
- Certain medications: Such as some diuretics and lithium.
- Other conditions: Overactive thyroid, prolonged immobilization, and granulomatous diseases like sarcoidosis.
- Dehydration and kidney problems: These can raise measured calcium and worsen the effects of an underlying cause.
In everyday practice, the great majority of cases trace back to either overactive parathyroid glands, which is the leading cause in otherwise well people, or an underlying cancer, which is the leading cause in those who are seriously ill.
Associated Symptoms
Symptoms depend on how high the calcium is and how quickly it rose:
- Excessive thirst and frequent urination
- Constipation, nausea, vomiting, and loss of appetite
- Bone pain and muscle weakness
- Kidney stones and flank pain
- Fatigue, confusion, depression, or difficulty thinking
Severe hypercalcemia can cause marked confusion, drowsiness, an irregular heartbeat, and even coma, all of which require emergency care.
Diagnosis & Evaluation
Hypercalcemia is confirmed with blood tests, and further tests find the cause.
- Blood tests: Measuring calcium, parathyroid hormone, vitamin D, and kidney function.
- Urine tests: To assess how much calcium the kidneys are handling.
- Imaging: Scans of the parathyroid glands, bones, or to look for an underlying cancer.
- ECG: Since high calcium can affect the heart rhythm.
Treatment & Management
Treatment depends on how high the calcium is and its cause.
- Mild cases: Often monitored, with attention to hydration and stopping any contributing supplements or medications.
- Hydration: Fluids, sometimes given through a vein, help the kidneys clear excess calcium.
- Medications: Drugs such as bisphosphonates can lower calcium, especially when cancer-related.
- Treating the cause: Surgery to remove an overactive parathyroid gland, or treatment of an underlying cancer or other condition.
- Emergency treatment: Severe hypercalcemia is treated urgently in hospital with fluids and medications to bring the level down quickly.
After treatment, ongoing monitoring of calcium levels is important to confirm the problem is controlled and to catch any recurrence, particularly when the underlying cause is a long-term condition.
Self-Care & Prevention
- Stay well hydrated, especially if you are prone to high calcium
- Use calcium and vitamin D supplements only as advised, not in excess
- Attend recommended blood test monitoring if you have a known risk
- Tell your doctor about all supplements and medications
- Report symptoms such as excessive thirst, confusion, or bone pain promptly
When to See a Doctor
See a doctor if a blood test shows high calcium or if you have ongoing symptoms such as excessive thirst, constipation, bone pain, kidney stones, or low mood. Seek emergency care for:
- Marked confusion, drowsiness, or difficulty staying awake
- Severe vomiting with signs of dehydration
- An irregular or very slow heartbeat, fainting, or collapse
Very high calcium can be life-threatening, so sudden severe symptoms warrant immediate medical attention.
Frequently Asked Questions
What does it mean to have high blood calcium?
Hypercalcemia means the calcium level in your blood is above normal. Mild cases often cause no symptoms, while higher levels can affect the bones, kidneys, digestion, and nervous system. The most common causes are overactive parathyroid glands and cancer.
What are the symptoms of high calcium?
Symptoms can include excessive thirst and urination, constipation, nausea, bone pain, muscle weakness, kidney stones, fatigue, and changes in mood or thinking. Mild hypercalcemia may cause no symptoms at all and be found on a blood test.
Can drinking water lower high calcium?
Staying hydrated helps the kidneys clear excess calcium and is part of treatment, especially for milder elevations. However, hydration alone does not treat the underlying cause, and significant hypercalcemia needs medical evaluation and specific treatment.
Is high calcium a sign of cancer?
It can be. Cancer is a common cause of hypercalcemia, particularly in people who are seriously ill or hospitalized. However, the most common overall cause in otherwise healthy people is overactive parathyroid glands, so high calcium needs proper evaluation rather than assumptions.
When is high calcium an emergency?
Severe hypercalcemia is an emergency. Seek immediate care for marked confusion, drowsiness, severe vomiting with dehydration, an irregular heartbeat, fainting, or collapse, as very high calcium can be life-threatening.
References
- MedlinePlus, U.S. National Library of Medicine. High blood calcium.
- Mayo Clinic. Hypercalcemia — Symptoms and causes.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Primary hyperparathyroidism.
- American Cancer Society. Hypercalcemia in people with cancer.