Appropriate Tests


Calcium, Albumin, Calcium (corrected), Phosphate.

Calcium (ionised), if indicated. Hypocalcaemia is only significant clinically if ionised calcium is reduced.

Low total, corrected, and ionised calcium:


  • Artefactual

Collection in EDTA, citrate or oxalate anticoagulant will result in a spurious reduction in calcium.

See Table 1.

  • Renal failure - chronic


  • Hypoparathyroidism


  • Vitamin D deficiency

See under Osteomalacia.

  • Hypomagnesaemia


  • Rhabdomyolysis

See under Myoglobinuria.

Low total calcium, normal corrected and ionised calcium:


  • Hypoalbuminaemia


Normal total and corrected calcium, low ionised calcium:


  • Hyperventilation


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