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# Hypercalcaemia

Blood calcium is high, nearly always from hyperparathyroidism or cancer. It causes stones, bone pain, gut upset and confusion.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Parathyroid glands](https://durgical.com/en/anatomy/parathyroid-glands/)
- [Kidneys](https://durgical.com/en/anatomy/kidney/)
- [Thyroid gland](https://durgical.com/en/anatomy/thyroid-gland/)
- [Pancreas](https://durgical.com/en/anatomy/pancreas/)
- [Stomach](https://durgical.com/en/anatomy/stomach/)

## In physiology

- [The ECG in potassium and calcium disorders](https://durgical.com/en/physiology/the-ecg-in-potassium-and-calcium-disorders/)
- [Calcium regulation: PTH, vitamin D and calcitonin](https://durgical.com/en/physiology/calcium-regulation-pth-vitamin-d-and-calcitonin/)
- [Transport in the loop of Henle](https://durgical.com/en/physiology/transport-in-the-loop-of-henle/)
- [Distal tubule and collecting duct](https://durgical.com/en/physiology/distal-tubule-and-collecting-duct/)
- [Reasoning through fluid and electrolyte imbalances](https://durgical.com/en/physiology/reasoning-through-fluid-and-electrolyte-imbalances/)
- [Renal handling of calcium, phosphate and magnesium](https://durgical.com/en/physiology/renal-handling-of-calcium-phosphate-and-magnesium/)

## Why it happens

- [Pathologic calcification: dystrophic vs metastatic](https://durgical.com/en/general-pathology/pathologic-calcification-dystrophic-vs-metastatic/)
- [Paraneoplastic syndromes: the table to know](https://durgical.com/en/general-pathology/paraneoplastic-syndromes-the-table-to-know/)

## What it is

A high serum calcium (corrected or ionised) from excess bone resorption, gut absorption or renal reabsorption.

## Who gets it

Primary hyperparathyroidism is the most common cause in outpatients and cancer in hospital patients; together they explain the vast majority of cases.

## Causes

- PTH-mediated: primary hyperparathyroidism (adenoma, hyperplasia), tertiary in kidney disease, familial hypocalciuric hypercalcaemia
- Cancer: PTHrP (squamous lung, breast, kidney carcinoma), lytic bone metastases, multiple myeloma, calcitriol-producing lymphomas
- Vitamin D: supplement toxicity, granulomas (sarcoidosis, tuberculosis)
- Drugs: thiazides, lithium, excess vitamin A, milk–alkali syndrome
- Others: prolonged immobilisation, hyperthyroidism, adrenal insufficiency

## Risk factors

- Postmenopausal women (hyperparathyroidism)
- Advanced cancer
- Lithium or thiazide use
- Excess calcium and vitamin D supplements
- Immobilisation

## Pathophysiology

PTH or PTHrP activate osteoclasts (via RANKL) and increase tubular calcium reabsorption; calcitriol raises gut absorption. High calcium over-stabilises membranes: neuromuscular excitability falls (weakness, hyporeflexia, constipation, confusion) and the QT shortens. In the kidney it activates the calcium-sensing receptor, causes nephrogenic diabetes insipidus (polyuria and dehydration, which worsen the hypercalcaemia), stones and nephrocalcinosis. It stimulates gastrin (ulcers) and can trigger pancreatitis.

## Classification

- With high or inappropriately normal PTH: hyperparathyroidism, familial hypocalciuric hypercalcaemia, lithium
- With suppressed PTH: cancer (PTHrP, metastases), vitamin D, granulomas, others
- Mild, moderate or severe per the laboratory and symptoms

## Symptoms and signs

- 'Bones, stones, abdominal groans and psychic moans': bone pain, kidney stones, abdominal pain, constipation, nausea, depression and confusion
- Thirst and polyuria
- Weakness and fatigue
- Many mild cases have no symptoms

## Red flags

- Confusion, drowsiness or coma
- Dehydration with acute kidney injury
- Short QT or arrhythmias
- Rapid-onset hypercalcaemia in someone with cancer

## Diagnosis

**Clinical**
History of cancer, drugs, supplements and symptoms of stones or bone pain; assessment of hydration.

**Tests**
Corrected or ionised calcium, PTH (the test that splits the causes), PTHrP, 25-hydroxy and 1,25-dihydroxyvitamin D, phosphate, creatinine, urine calcium (hypercalciuria vs familial hypocalciuric), protein electrophoresis if myeloma is suspected, ECG.

**Imaging**
Sestamibi scan and neck ultrasound to locate a parathyroid adenoma; bone densitometry; renal ultrasound for stones; imaging to look for cancer when PTH is suppressed.

## Treatment

**Acute**
Severe hypercalcaemia: intravenous saline rehydration as the first step

**Medical**
Halt bone resorption: intravenous bisphosphonates or denosumab; calcitonin for a fast, short effect

**Surgical**
Parathyroidectomy in symptomatic primary hyperparathyroidism or when surgical criteria are met

**Medical**
Treat the cause: corticosteroids in granulomas or lymphoma, cancer treatment, stop thiazides, lithium or supplements; dialysis in refractory cases

**Follow-up**
Monitoring of calcium, [kidney](https://durgical.com/en/anatomy/kidney/) function and hydration

## Complications

- Acute kidney injury and nephrocalcinosis
- Kidney stones
- Arrhythmias
- Pancreatitis and peptic ulcer
- Osteoporosis and fractures (hyperparathyroidism)
- Coma

## Prognosis

Primary hyperparathyroidism has a good outlook with surgery; hypercalcaemia of malignancy usually signals advanced disease.

## Prevention

- Avoiding excess calcium and vitamin D supplements
- Monitoring calcium on lithium or thiazides
- Hydration and early mobilisation of immobilised patients

## Test yourself

Think of the answer, then tap the question to see it.

## Which test splits the causes of hypercalcaemia?

PTH: high or inappropriately normal in hyperparathyroidism; suppressed in cancer, vitamin D toxicity and granulomas.

## Which substance do some tumours make to raise calcium?

PTH-related peptide (PTHrP), typical of squamous cell lung carcinoma.

## Why does hypercalcaemia cause polyuria?

High calcium stops the collecting duct responding to ADH (nephrogenic diabetes insipidus).

## What is the first step in treating severe hypercalcaemia?

Intravenous saline rehydration, because dehydration worsens hypercalcaemia; bone resorption is then halted.

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## Related conditions

- [Hypocalcaemia](https://durgical.com/en/conditions/hypocalcaemia/)
- [Primary hyperparathyroidism](https://durgical.com/en/conditions/primary-hyperparathyroidism/)
- [Lung cancer](https://durgical.com/en/conditions/lung-cancer/)
- [Breast cancer](https://durgical.com/en/conditions/breast-cancer/)
- [Kidney stones (urolithiasis)](https://durgical.com/en/conditions/kidney-stones/)
- [Acute pancreatitis](https://durgical.com/en/conditions/acute-pancreatitis/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Hypercalcemia: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000365.htm) (MedlinePlus, US National Library of Medicine, 2026); [Hyperparathyroidism: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/001215.htm) (MedlinePlus, US National Library of Medicine, 2026); [Parathyroid hormone-related protein blood test: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003691.htm) (MedlinePlus, US National Library of Medicine, 2026); [Calcium Blood Test: MedlinePlus Medical Test](https://medlineplus.gov/lab-tests/calcium-blood-test/) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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