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HelpTest Code MYGLU Myoglobin, Random, Urine
Reporting Name
Myoglobin, Random, UUseful For
Confirming the presence of a myopathy
Method Name
Electrochemiluminescent Immunoassay (ECLIA)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
UrineSpecimen Required
Supplies: Urine Myoglobin Transport Tube (T691)
Container/Tube: Plastic, 5-mL urine myoglobin transport tube
Specimen Volume: 4 mL
Collection Instructions:
1. Collect a preservative-free, random urine specimen.
2. If specimen is at ambient temperature, aliquot the urine to a urine myoglobin transport tube within 1 hour of collection. Refrigerate specimen.
3. If specimen is at refrigerate temperature, aliquot the urine to a urine myoglobin transport tube within 2 hours of collection.
Additional Information: Urinary myoglobin is highly unstable unless alkalinized with sodium carbonate preservative.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated | 7 days | MYOGLOBIN TRANSPORT TUBE |
Reject Due To
| Use of any transport tube other than urine myoglobin transport tube | Reject |
Reference Values
0-24 mcg/L
Reference values have not been established for patients younger than 18 years; however myoglobin is not expected to be detectable in urine.
Day(s) Performed
Monday through Sunday
CPT Code Information
83874
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| MYGLU | Myoglobin, Random, U | 2641-9 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| MYGLU | Myoglobin, Random, U | 2641-9 |
Clinical Information
Myoglobin is a small 17.8 kDa oxygen-binding heme protein, present in striated muscle to carry and store oxygen in muscle cells. By virtue of its small size, myoglobin is readily filtered by the glomerulus and catabolized by endocytosis and proteolysis in the proximal tubule. Healthy subjects normally have low concentrations (less than 5%) of protein appearing in the urine. Injury to skeletal or cardiac muscle results in a large release of myoglobin into systemic circulation within a few hours, which can overwhelm tubular resorption causing notable quantities of myoglobin to appear in urine giving it a red-brown appearance. The presence of myoglobin in the urine is a risk factor for developing acute kidney injury. Myoglobin concentration declines rapidly, with a serum half-life of 2 to 3 hours and has been studied for its ability to predict acute kidney injury.
High concentrations appear very rapidly in the urine in various conditions, including some metabolic diseases.
Conditions that can lead to rhabdomyolysis associated with myoglobinuria include:
-Trauma or crush injury
-Heatstroke, hypothermia, malignant hyperthermia
-Seizures, strenuous exercise, prolonged immobility
-Hypoxic injury
-Metabolic disturbances in electrolyte concentrations
-Genetic disorders that lead to muscle cell breakdown
-Infections
-Drugs or toxins
The presence of myoglobin in the urine can indicate serious muscle injury, which is a risk factor for developing acute kidney injury. Rhabdomyolysis is often confirmed and monitored by measuring serum creatine kinase, electrolytes, kidney function, and urine tests for protein and blood. Myoglobin will give a positive reaction with hemoglobin test strips, though red blood cells will be absent upon microscopic review.
Interpretation
Increased excretion of urinary myoglobin is suggestive of one of the disorders or conditions listed in Clinical Information.
Most clinically significant elevations are elevated 2 to 10 times normal.
Cautions
An elevated level of urinary myoglobin alone does not identify the clinical disorder.
Physiological variables, such as patient hydration status, acid-base status, kidney function, and hypoxia affect myoglobin metabolism and, consequently, its presence in urine.
Urinary myoglobin concentration deteriorates rapidly unless stabilized immediately after collection by alkalinizing with sodium carbonate. Urine collected with any preservative other than sodium carbonate will not provide valid results.
Urinary myoglobin does not withstand freezing even when the pH is raised with sodium carbonate.
Method Description
This myoglobin test is a sandwich-principal assay. The first incubation is 9 mcL of sample, a biotinylated monoclonal myoglobin-specific antibody, and a monoclonal myoglobin-specific antibody labeled with a ruthenium complex, which react to form a sandwich complex. In the second incubation, the complex becomes bound to the solid phase via interaction of biotin and streptavidin after addition of streptavidin-coated microparticles. The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Results are determined via a calibration curve, which is instrument specifically generated by 2-point calibration, and a master curve provided via the cobas link.(Package insert: Elecsys Myoglobin. Roche Diagnostics; 10/2022)