Table 3.

Causes of hypocalcemia.

Factitious (sample contamination with EDTA)

Normal plasma ionised with reduced total calcium (hypoalbuminaemia)

Reduced plasma ionised with normal total calcium (respiratory alkalosis, citrate toxicity found in transfusion)

Reduced plasma ionised and total calcium

(i) Decreased PTH activity (hypoparathyroidism, pseudohypoparathyroidism, and hypomagnesaemia)

(ii) Vitamin D deficiency

(iii) Excessive calcium losses (critical illness, malabsorption, pancreatitis, and diuresis)