Clinical Biochemistry

Magnesium (blood)

Test Background
Hypomagnesaemia (often associated with hypokalaemia and/or hypocalcaemia) may reflect inadequate dietary intake (eg. malnutrition, alcoholism, etc.), inadequate absorption by the GI tract (eg. Crohn’s, diarrhoea) or excessive renal excretion (eg. secondary to diabetes mellitus, long-term use of diuretics). In contrast, increased serum magnesium typically reflects kidney failure, hyperparathyroidism, Addison’s disease or is due to the administration of magnesium-containing compounds, eg. laxatives, antacids and magnesium sulphate (used in the prophylaxis of eclampsia).

Clinical Indications
Investigation of hypocalcaemia and/or hypokalaemia Monitoring/diagnosis of electrolyte and acid/base disturbance Hyperparathyroidism Monitoring of pre-eclampsia

Reference Range

Sample Required
SST (gold top) or Red top

Sample Volume
0.5 mL

Turnaround Time
1 day