Differential Diagnosis of Hypercalcaemia

Non malignant causes of hypercalcaemia include:

Chronic renal failure
Endocrine disorders (hyperthyroidism, phaeochromocytoma, Addisons disease)
Familial hypocalciuric hypercalcaemia
Immobilisation
Laboratory artifact due to altered albumin concentration or serum pH
Medications (vitamin A toxicity [dietary fads, isotretinoin overdose, multivitamin overdose], oestrogens, antioestrogens, thiazides, lithium)
Milk-alkali syndrome
Primary hyperparathyroidism
Vitamin D toxicity
Granulomatous disease (sarcoidosis, tuberculosis)

Malignancies causing hypercalcaemia

Table 1: Tumours most often associated with hypercalcaemia [5]
??Malignancy	Frequency
Multiple myeloma	40 to 50%
Breast	>20%
Lung	Usually squamous cell
Squamous cell cancers of head, neck, oesophagus and thyroid	Rarely