Test Details
Methodology
Nuclear magnetic resonance (NMR) or Enzymatic
Result Turnaround Time
3 - 5 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.
Use
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. The mean urinary citrate excretion rate in patients with idiopathic calcium urolithiasis has been found to be significantly lower than that of control groups. Hypocitraturia is common in patients with urolithiasis resulting from renal tubular acidosis and in patients with enteric hyperoxaluria. Citrate excretion is low in renal insufficiency.
Special Instructions
pH must be 1 to 3 or the sample frozen without the addition of acid.
Limitations
This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.
Specimen Requirements
Specimen
Urine (random), acidified or frozen
Volume
2 mL
Minimum Volume
1 mL (Note: This volume does not allow for repeat testing.)
Container
Use random urine transport tube or urine Monovette® with pH stabilizer (Labcorp No. 56015). Monovette® instructions accompany units.
Collection Instructions
Collect urine and transfer to a random urine transport tube or urine Monovette® with pH stabilizer (Labcorp No. 56015). Alternatively, the sample may be frozen without added acid.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 29 days |
Refrigerated | 29 days |
Frozen | 49 days |
Freeze/thaw cycles | Stable x5 |
Reference Range
See table.
Gender | Age (y) | Range (mg/L) |
|---|---|---|
Male | <40 | 9−864 |
≥40 | 7−1130 | |
Female | <40 | 40−1930 |
≥40 | 10−1560 |
Storage Instructions
Refrigerate at 2°C to 8°C.
Causes for Rejection
Citrate: Boric Acid used as a preservative (Boric acid ≥1250 mg/dL may cause citrate results to be reduced by approximately 30%); multivitamin ≥397.5 mg/dL (estimated as 1 pill per day) may cause citrate results to be unmeasurable. Results of interference testing may not be representative of in-vivo characteristics of multivitamin consumption.
References
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 123866 | Citric Acid(Citrate), Random U | 2128-7 | 016869 | Citric Acid, Random Urine | mg/L | 2128-7 |
| Order Code | 123866 | |||||
| Order Code Name | Citric Acid(Citrate), Random U | |||||
| Order Loinc | 2128-7 | |||||
| Result Code | 016869 | |||||
| Result Code Name | Citric Acid, Random Urine | |||||
| UofM | mg/L | |||||
| Result LOINC | 2128-7 |