Tubular Reabsorption of Phosphorus, Random Urine and Serum
Test Mnemonic
TRPHOS
CPT Codes
- 82565 - QTY (1)
- 82570 - QTY (1)
- 84100 - QTY (1)
- 84105 - QTY (1)
Aliases
- Hypophosphatemia
- Phosphate
Includes
- Phosphorus (inorganic), serum
- Tubular reabsorption of phosphate (TRP)
- Maximum rate of tubular phosphate reabsorption to glomerular filtration rate (TmP/GFR) ratio
- Creatinine, Serum
- Creatinine, Random urine
Performing Laboratory
Mayo Clinic Dpt of Lab Med & Pathology
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 0.5 mL | Serum | No additive (Red) | Refrigerated | Fasting required. Both serum and urine are required. Separate serum from cells ASAP and transfer to standard aliquot tube. Label specimen as serum. | |
| 4 mL | Urine, random | Clean container | Refrigerated | Both serum and urine are required. Label specimen as urine. |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 0.5 mL | Serum | ||||
| 1 mL | Urine |
Stability
| Environmental Condition | Description |
|---|---|
| Frozen | Serum: 90 days; Urine: 30 days |
| Refrigerated | Serum: 7 days; Urine:14 days |
| Ambient | Serum: Unacceptable; Urine: 7 days |
Days Performed
Sun - Sat
Turnaround Time
1 - 2 days
Methodology
| Name | Description |
|---|---|
| Calculation | |
| Colorimetric Enzyme Assay | |
| Photometric |
Special Info
Fasting is required. Both serum and urine are required. Grossly hemolyzed specimens will be rejected. This test is New York state approved.
Clinical Info
This test is useful for assessing renal reabsorption of phosphorus in a variety of pathological conditions associated with hypophosphatemia including hypophosphatemic rickets, tumor-induced osteomalacia, and tumoral calcinosis. It is also useful for adjusting phosphate replacement therapy in severe deficiency states monitoring the renal tubular recovery from acquired Fanconi syndrome.