Test Details
Methodology
Colorimetric
Result Turnaround Time
1 - 2 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Test Includes
Phosphorus on random or timed urine specimen
Use
Evaluate calcium/phosphorus balance.
High urinary phosphorus (ie, increased renal losses) occurs in primary hyperparathyroidism, vitamin D deficiency, renal tubular acidosis, diuretic use. Phosphates are among the substances which may be lost in the Fanconi syndrome. Renal loss of phosphate may itself lead to rickets or osteomalacia.
Low in hypoparathyroidism, pseudohypoparathyroidism, vitamin D intoxication
Evaluate nephrolithiasis. Hypophosphatemia with normal serum calcium, high alkaline phosphatase, hypercalciuria, low urinary phosphorus occur with osteomalacia from excessive antacid ingestion. The relationship between serum PO4 and phosphaturia, the phosphate excretion index, is described.1 Largely, however, urine phosphate simply reflects phosphate intake in patients not on phosphate binding medications.
Special Instructions
The test request form must state date and time collection started, date and time collection finished, and urine volume. Specimens submitted without preservative should be acidified after receipt to pH <2.0 with 6N HCl.
Custom Additional Information
Children with thalassemia may have normal phosphorus absorption, but high renal phosphaturia, leading to a deficiency of phosphorus.2 Increasing dietary intake of potassium has been reported to increase serum phosphate concentrations apparently by decreasing renal excretion of phosphate.3 During the last trimester of pregnancy there is a sixfold increase in calcium and phosphorus accumulation as the fetus triples its weight. Plasma phosphorus concentrations and increased urinary phosphate may provide a useful means to assess response to phosphate supplements in the premature infant.4
Specimen Requirements
Specimen
Urine (24-hour)
Volume
10 mL aliquot of entire collection
Minimum Volume
0.5 mL aliquot (Note: This volume does not allow for repeat testing.)
Container
Plastic urine container. Collect with 6N HCl.
Collection Instructions
Instruct the patient to void at 8 AM and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Screw the lid on securely. Mix well. pH must be 0 to 2.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Reference Range
See table.
Age | Male (mg/24 hr) | Female (mg/24 hr) |
|---|---|---|
0 to 5 y | Not established | Not established |
6 to 12 y | 130–941 | 130–941 |
13 to 80 y | 390–1425 | 261–1078 |
>80 y | 210–888 | 96–706 |
Storage Instructions
Maintain specimen at room temperature.
Causes for Rejection
Improper labeling
Footnotes
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 003251 | Phosphorus, 24 hr Urine | 2779-7 | 013599 | Phosphorus, Urine | mg/dL | 2778-9 |
| 003251 | Phosphorus, 24 hr Urine | 2779-7 | 013250 | Phosphorus,Urine 24h | mg/24 hr | 2779-7 |
| Order Code | 003251 | |||||
| Order Code Name | Phosphorus, 24 hr Urine | |||||
| Order Loinc | 2779-7 | |||||
| Result Code | 013599 | |||||
| Result Code Name | Phosphorus, Urine | |||||
| UofM | mg/dL | |||||
| Result LOINC | 2778-9 | |||||
| Order Code | 003251 | |||||
| Order Code Name | Phosphorus, 24 hr Urine | |||||
| Order Loinc | 2779-7 | |||||
| Result Code | 013250 | |||||
| Result Code Name | Phosphorus,Urine 24h | |||||
| UofM | mg/24 hr | |||||
| Result LOINC | 2779-7 |