Renal function test, evaluate calcium/phosphorus balance. Normal phosphate excretion reflects the dietary intake of phosphate. The excretion varies with growth, dietary intake, renal function, muscle mass and hormonal activity. Urinary phosphate excretion will be decreased in hyperthyroidism.
400 - 1200 mg/TV (24 hour collection). Random urine collections vary with dietary intake and are dependent on diurnal variation, and are reported in units of mg/dL, for which reference values are not established.
Collect 24 hour urine specimen with no preservative. Aliquot 5 mL into a plastic urine container and refrigerate. Record total 24 hour urine volume and collection dates/times on request form. Random urine also acceptable.