Test Details
Methodology
Enzymatic (creatinase)/spectrophotometry
Result Turnaround Time
3 - 6 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
Determine creatinuria; increased urine creatine values may be obtained from diseases that reduce muscle mass, including fasting, muscular dystrophy, poliomyelitis, atrophy, inflammatory destructive muscle disease as polymyositis, hyperthyroidism, as well as corticosteroid induced myopathy.
Special Instructions
State patient's sex and 24-hour total urine volume on the request form.
Custom Additional Information
Creatine is endogenously synthesized in the kidney, liver, and pancreas. It is transported in blood to other organs such as muscle and brain, where it is phosphorylated to phosphocreatine. Interconversion of phosphocreatine and creatine is a unique feature of the metabolic processes of muscle contraction; some of the free creatine in muscle spontaneously converts to creatinine, its anhydride. Between 1% and 2% of muscle creatine is converted to creatinine daily.
Specimen Requirements
Specimen
Urine (24-hour), frozen
Volume
2 mL aliquot
Minimum Volume
0.2 mL aliquot (Note: This volume does not allow for repeat testing.)
Container
Plastic urine container, no preservative
Collection Instructions
Instruct the patient to void at 8 AM and discard the specimen. Then collect all the urine, including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Measure and record on the test request form the 24-hour total volume. Mix well. Transfer the urine into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Label the container with the patient's name, date, and time collection started and finished. The specimen should be frozen immediately and maintained frozen until tested.
Reference Range
Male: 0−40 mg/24 hours; female: 0−80 mg/24 hours
Storage Instructions
Freeze
Causes for Rejection
Thawed specimen; 6N HCl, boric acid, or alkali added to collection (Acid or alkali preservative will convert creatine to creatinine, falsely lowering creatine values.)
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 003475 | Creatine, 24-Hour Urine | 003477 | Creatine,U,mg/dL | mg/dL | 2149-3 | |
| 003475 | Creatine, 24-Hour Urine | 003476 | Creatine,24-hr Ur | mg/24 hr | 2150-1 | |
| Order Code | 003475 | |||||
| Order Code Name | Creatine, 24-Hour Urine | |||||
| Order Loinc | ||||||
| Result Code | 003477 | |||||
| Result Code Name | Creatine,U,mg/dL | |||||
| UofM | mg/dL | |||||
| Result LOINC | 2149-3 | |||||
| Order Code | 003475 | |||||
| Order Code Name | Creatine, 24-Hour Urine | |||||
| Order Loinc | ||||||
| Result Code | 003476 | |||||
| Result Code Name | Creatine,24-hr Ur | |||||
| UofM | mg/24 hr | |||||
| Result LOINC | 2150-1 |