Overview
Hypercalcaemia, or an increased serum calcium concentration >2.60 mmol/L, shortens action potentials which primarily results in early ventricular repolarisation (shortened QT) on ECG.
Pathogenesis
Causes of Hypercalcaemia
- Malignancy - local osteolysis, humoral hypercalcaemia of malignancy, multiple myeloma
- Hyperparathyroidism (primary / secondary / tertiary)
- Endocrine - thyrotoxicosis, Addison's disease
- Granulomatous disease - sarcoidosis, tuberculosis
- Prolonged immobilisation
- Drugs - calcium supplements, vitamin D, vitamin A, thiazides, lithium, oestrogens, anti-oestrogens, progestins
- Total parenteral nutrition (TPN)
- Familial hypercalcaemia-hypercalciuria (FHH)
Manifestations
Signs and Symptoms
- Renal ('stones') - nephrolithiasis, nephrocalcinosis, nephrogenic diabetes insipidus
- GI ('groans') - nausea, reflux, peptic ulcers, pancreatitis, constipation
- CNS ('moans') - lethargy, depression, confusion, memory loss, coma
- MSK ('bones') - osteopaenia, bone pain, pathologic fractures
- Cardiovascular - hypertension, shortened QT
Diagnosis
Bloods
- Total calcium >2.60 mmol/L
- Ionised calcium >1.35 mmol/L
ECG Findings
- Shortened QT interval (due to a shortened ST segment)
- Osborn waves (J waves) - dome or hump-shaped deflections following the J point
- QRS prolongation
- PR prolongation
Severe hypercalcaemia may produce ST elevation and T wave inversion that mimics an acute myocardial infarction.
Further Investigations
- Check the patient's PTH
- If not elevated - check the PTH-related peptide (PTHrp), 25-hydroxy-vitamin D and 1,25-dihydroxy-vitamin D levels
- Elevated alkaline phosphatase (ALP) is suggestive of local osteolysis
- Specific tests such as TFTs, cortisol and myeloma screen may be useful
Next Page
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------