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HelpTest ID: CRBF Creatinine, Body Fluid
Reporting Name
Creatinine, BFSpecimen Type
Body FluidNecessary Information
1. Date and time of collection are required.
2. Specimen source is required.
Specimen Required
Specimen Type: Body fluid
Preferred Source:
-Peritoneal fluid (peritoneal, abdominal, ascites, paracentesis)
-Pleural fluid (pleural, chest, thoracentesis)
-Drain fluid (drainage, JP drain)
-Peritoneal dialysate (dialysis fluid)
-Pericardial
Acceptable Source: Write in source name with source location (if appropriate)
Collection Container/Tube: Sterile container
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Centrifuge to remove any cellular material and transfer into a plastic vial.
2. Indicate the specimen source and source location on label.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Body Fluid | Refrigerated (preferred) | 7 days | |
| Frozen | 30 days | ||
| Ambient | 24 hours |
Reference Values
An interpretive report will be provided.
Day(s) Performed
Monday through Sunday
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
82570
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CRBF | Creatinine, BF | 12190-5 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| CR_BF | Creatinine, BF | 12190-5 |
| FLD13 | Fluid Type, Creatinine | 14725-6 |
Clinical Reference
1. Manahan KJ, Fanning J. Peritoneal fluid urea nitrogen and creatinine reference values. Obstet Gynecol. 1999;93:780-782
2. Wong MH, Lim SK, Ng KL, Ng KP. Pseudo-acute kidney injury with recurrent ascites due to intraperitoneal urine leakage. Intern Med J. 2012;42(7):848-849
3. Austin A, Jogani SN, Brasher PB, Argula RG, Huggins JT, Chopra A. The urinothorax: A comprehensive review with case series. Am J Med Sci. 2017;354(1):44-53
4. Toubes ME, Lama A, Ferreiro L, et al. Urinothorax: a systematic review. J Thorac Dis. 2017;9(5):1209-1218
5. Block DR, Florkowski CM. Body fluids. In: Rafai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018: chap 43
6. Saenger AK, Lockwood C, Snozek CL, et al. Catecholamine interference in enzymatic creatinine assays. Clin Chem. 2009;55(9):1732-1736
Report Available
Same day/1 to 2 daysMethod Name
Enzymatic
Useful For
Identifying the presence of urine as a cause for accumulation of fluid in a body compartment
Measuring the ultrafiltration capacity of the peritoneal membrane in patients receiving peritoneal dialysis
Clinical Information
Byproducts of nitrogen metabolism are present in high concentration in urine compared to blood and serve as a surrogate marker for the identification of urine leakage into a body compartment. Concentrations of creatinine or urea nitrogen that exceed the concentration found in a concurrent sample of blood are suggestive of the presence of urine.(1)
Peritoneal, abdominal, pelvic drain fluid:
Trauma as well as abdominal or pelvic surgery can lead to bladder perforation or formation of urinary fistula with excessive accumulation of peritoneal fluid or increased surgical drain output caused by intraperitoneal urinary leakage.(1,2)
Pleural fluid:
Urinoma describes the accumulation of urine in the perirenal and retroperitoneal spaces caused by genitourinary tract injury due to trauma or blockage of the urinary tract due to stones, strictures, tumors, benign prostate hypertrophy, etc.(3) Rarely, this fluid can translocate to the pleural cavity causing pleural effusion via movement of urine through the diaphragm or via lymphatic communication between retroperitoneal and pleural spaces caused by increased pressure due to urinoma. Urinothorax is the term used to describe an accumulation of urine in the pleural space. Patients often develop symptoms of dyspnea, chest pain, abdominal pain, and reduced diuresis.(4) The condition is reversed when treatment is directed to correct the primary cause (trauma in 75% and obstruction in 24% of cases). The pleural fluid to serum creatinine ratio is above 1 in 97.9% of cases (n=48; median ratio=2.9, range=0.95-16).
Peritoneal dialysis fluid:
Peritoneal dialysis (PD) is a type of ambulatory dialysis in which hyperosmotic fluid is infused into the patient's peritoneal cavity, with the peritoneum employed as the dialysis membrane promoting the diffusion of small molecules and free water from circulation.(5) The peritoneal equilibration test estimates the rate of small solute transport across the peritoneal membrane and the ultrafiltration capacity. Several analytes may be measured in order to perform this test. Creatinine is measured in PD fluid as well as in plasma or serum in samples taken 2 and/or 4 hours after the dialysate is instilled. The dialysate fluid to serum or plasma creatinine ratio is calculated with larger ratios (approaching 1.0) observed in patients exhibiting faster transport rates.
Interpretation
Peritoneal, pleural, and drain fluid concentrations should be compared to serum or plasma. Fluid to serum ratios above 1.0 suggest the specimen may be contaminated with urine.(1-4)
Peritoneal dialysate fluid to serum creatinine ratios can be calculated from timed collections to determine peritoneal membrane transport rates.(5)
All other fluids: results should be interpreted in conjunction with serum creatinine and other clinical findings.
Forms
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.
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