Home
HelpTest ID RPOU Phosphorus, Pediatric, Random, Urine
Reporting Name
Phosphorus, Pediatric, Random, UUseful For
Evaluation of hypo- or hyperphosphatemic states
Evaluation of patients with nephrolithiasis
Specimen Type
UrineSpecimen Required
Container/Tube: Plastic, 5-mL tube (T465)
Specimen Volume: 4 mL
Collection Instructions:
1. Collect a random urine specimen.
2. No preservative.
Additional Information: A timed 24-hour urine collection is the preferred specimen for measuring and interpreting this urinary analyte. Random collections normalized to urinary creatinine may be of some clinical use in patients who cannot collect a 24-hour specimen, typically small children. Therefore, this random test is offered for children <16 years old.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Refrigerated (preferred) | 14 days |
| Frozen | 14 days | |
| Ambient | 7 days |
Reference Values
No established reference values
Day(s) and Time(s) Performed
Monday through Sunday
Test Classification
This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
84105
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| RPOU | Phosphorus, Pediatric, Random, U | In Process |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| POCON | Phosphorus, Pediatric, Random, U | 2778-9 |
| CREA6 | Creatinine Concentration | 2161-8 |
| RATO5 | Phosphorus/Creatinine Ratio | 11141-9 |
Clinical Information
Approximately 80% of filter phosphorus is reabsorbed by renal proximal tubule cells. The regulation of urinary phosphorus excretion is principally dependent on regulation of proximal tubule phosphorus reabsorption. A variety of factors influence renal tubular phosphate reabsorption, and consequent urine excretion. Factors that increase urinary phosphorus excretion include high phosphorus diet, parathyroid hormone, extracellular volume expansion, low dietary potassium intake and proximal tubule defects (eg, Fanconi syndrome, X-linked hypophosphatemic rickets, tumor-induced osteomalacia). Factors that decrease, or are associated with decreases in, urinary phosphorus excretion include low dietary phosphorus intake, insulin, high dietary potassium intake, and decreased intestinal absorption of phosphorus (eg, phosphate-binding antacids, vitamin D deficiency, malabsorption states).
A renal leak of phosphate has also been implicated as contributing to kidney stone formation in some patients.
A timed 24-hour urine collection is the preferred specimen for measuring and interpreting this urinary analyte. Random collections normalized to urinary creatinine may be of some clinical use in patients who cannot collect a 24-hour specimen, typically small children. Therefore, this random test is offered for children <16 years old.
Interpretation
Interpretation of urinary phosphorous excretion is dependent upon the clinical situation, and should be interpreted in conjunction with the serum phosphorous concentration.
|
Pediatric Reference Ranges on a Random Specimen Phosphate/Creatinine (mg/mg)(1) |
||
|
Age (year) |
5th Percentile |
95th Percentile |
|
0-1 |
>0.34 |
<5.24 |
|
1-2 |
>0.34 |
<3.95 |
|
2-3 |
>0.34 |
<3.13 |
|
3-5 |
>0.33 |
<2.17 |
|
5-7 |
>0.33 |
<1.19 |
|
7-10 |
>0.32 |
<0.97 |
|
10-14 |
>0.22 |
<0.86 |
|
14-17 |
>0.21 |
<0.75 |
Clinical Reference
1. Matos V, van Melle G, Boulat O et al: Urinary phosphate/creatinine, calcium/creatinine, and magnesium/creatinine ratios in a healthy pediatric population. J Pediatr 1997;131:252-257
2. Agarwal R, Knochel JP: Hypophosphatemia and hyperphosphatemia. In The Kidney. Sixth edition. Edited by Barry M Brenner. WB Saunders Company, Philadelphia, PA, 2000, pp 1071-1125
Analytic Time
1 dayMethod Name
Molybdic Acid