Phosphorus (phosphate) is an essential mineral involved in bone health, energy metabolism, and cell function.

The 24-hour urine test provides an accurate measure of phosphate excretion compared to a random urine sample.

Clinical uses include:

Assessing kidney function and phosphate handling.

Investigating causes of hypophosphatemia (low phosphate) or hyperphosphatemia (high phosphate).

Monitoring patients with renal disease, bone disorders, or parathyroid gland abnormalities.

Evaluating dietary phosphate intake and excretion balance.

The test requires collecting all urine passed in 24 hours in a special container.

Analyte: Phosphorus concentration in 24-hour urine.

Normal Range: Approximately 0.4–1.3 g/24 hrs (varies by lab and diet).

High Phosphorus Excretion: May indicate hyperparathyroidism, renal tubular disorders, high dietary intake, or vitamin D excess.

Low Phosphorus Excretion: May suggest hypoparathyroidism, chronic kidney disease, malnutrition, or vitamin D deficiency.

Clinical Use:

Detects abnormalities in phosphate metabolism.

Differentiates renal vs non-renal causes of phosphate imbalance.

Supports diagnosis of endocrine, bone, and renal disorders.