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HelpTest Code NEOTRP TRP (Tubular Reabsorption of Phosphorus)
Specimen Requirements
| Fasting Required | Specimen Type | Preferred Container/Tube | Acceptable Container/Tube | Specimen Volume | Specimen Minimum Volume (allows for 1 repeat) |
Pediatric Minimum Volume (no repeat) |
|---|---|---|---|---|---|---|
| Yes |
Urine |
Urine Container |
1-3 mL |
0.5 mL |
||
| Yes | Plasma or Serum | Plasma Separator Tube (PST) | Serum Separator Tube (SST) or Red Top Tube (RTT) | 0.5 mL | 0.3 mL |
Collection/Processing Instructions
**This test requires both urine AND plasma or serum.**
Adults: Patients should be fasting for at least 8 hours. Water is permitted during this fasting period.
Draw fasting specimen and separate serum from the blood within 60 minutes of venipuncture for phosphorus and creatinine.
Specimen must be free of particulate matter including fibrin.
Avoid venous statis.
For urine collect a random urine specimen without preservatives after voiding the morning urine. 24 hours urine is also acceptable, record total volume of the urine. Acceptable preservatives include 7 g sulfamic acid, 6N HCL.
Newborns: Draw 0.2 mL serum (1 mL red microtainer) and 1 mL random urine with no preservatives. Serum phosphorus has circadian rhythm (highest in the morning and lowest in the evening) and also subject to seasonal variation (maximum level in May and June, and low in winter months).
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Ambient | 2 hours |
| Refrigerate | 4 days | |
| Plasma/Serum | Ambient | 8 hours |
| Refrigerate | 2 days | |
| Frozen | 2 months |
Rejection Criteria
Test cannot be performed unless both a blood and urine specimen are available.
Test Components
Tests performed include serum and urine phosphorus, serum and urine creatinine plus a calculation for percent tubular reabsorption of phosphorus.
Test Information
In adults, the test lacks sensitivity and will give normal results in 25% of patients with hyperparathyroidism. Renal insufficiency will invalidate the test, causing a falsely low result.
Reference Range Information
| Performing Location | Reference Range |
|---|---|
| Marshfield | % TRP: 82-95% See individual listings for serum and urine phosphorus and creatinine results |
Marshfield Labs Performing Department
Marshfield Labs Chemistry
Performing Information
| Performing Location | Day(s) Test Performed | Analytical Time | Methodology/Instrumentation |
|---|---|---|---|
| Marshfield | Monday through Sunday | 2-4 hours | Phosphomolybdate Complex Endpoint Assay & Modified Jaffe Kinetic Fixed Assay/Beckman AU |
CPT Codes
| CPT | Modifier (if needed) |
Quantity | Description | Comments |
|---|---|---|---|---|
| 84105 | Phosphorus, urine | |||
| 82570 | Creatinine, urine | |||
| 84100 | Phosphorus, serum | |||
| 82565 | Creatinine, serum |
Outreach CPT Codes
| CPT | Modifier (if needed) |
Quantity | Description | Comments |
|---|---|---|---|---|
| 84105 | Phosphorus, urine | |||
| 82570 | Creatinine, urine | |||
| 84100 | Phosphorus, serum | |||
| 82565 | Creatinine, serum |
Ordering Applications
| Ordering Application | Description |
|---|---|
| Cerner | TRP (Tubular Reabsorp of Phos) |