Pathology tests database

Sample and container requirements

Plain Spot Urine Plain 24 hr Urine

Minimum volume required

500 µL

Special requirements

None

Patient preparation

None

Sample viability

Turnaround time

This assay is run throughout the day and night. The in-lab turnaround time is normally less than 24 hours.

Reference range

2.4 – 6.5 mmol/24 hr (Source: Pathology Harmony Recommendations)

Clinical guidance

Measurement of urinary magnesium is helpful in the diagnosis and investigation of magnesium deficiency. Low urinary magnesium concentrations may occur due to reduced renal excretion, for example in dehydration, or from inadequate magnesium intake, such as in malnutrition or malabsorption. Increased urinary magnesium excretion may be associated with conditions including hyperaldosteronism, osmotic diuresis, chronic glomerulonephritis, and treatment with certain drugs such as cisplatin. The presence of significant urinary magnesium excretion in a patient with a low serum magnesium concentration is suggestive of renal magnesium loss as the cause of the hypomagnesaemia.

Notes