Bluegrass Community Hospital
Laboratory
360 Amsden Avenue
Versailles, Kentucky 40383
Policy Description:
Urine Myoglobin Screen
Prepared by:
Approved by:
_______________________________ ______
Norma J. Whitworth, BSMT(ASCP)
Date
Laboratory Manager
________________________________
Richard Lozano, M.D.
Medical Director
Effective Date:
_______
Date
Revised:
Annual Review:
Principle:
Myoglobin is a protein present in cardiac and skeletal muscles. When exercising, muscles use up
available oxygen. The Myoglobin protein has oxygen bound to its molecule that provides extra
oxygen during strenuous exercise or muscle injury, allowing the muscles to function for a longer
period of time. Myoglobin is then released into the blood stream, filtered by the kidneys and excreted
in urine. It will cause the urine color to appear reddish-brown. The degree of coloration can resemble
a cola drink or black coffee, indicating that myoglobin was released in large quantities.
When there is acute destruction of muscle fibers (Rhabdomyolysis), large amounts of Myoglobin is
released and can cause renal damage. However, renal failure from myoglobinuria may not be
recognized until a week or more after the damaging occurrence. The following table lists some causes
of Rhabdomyolysis and Myoglobinuria:
CAUSES OF RHABDOMYOLYSIS AND MYOGLOBINURIA
Polymyositis and dermatomyositis (acute, Toxic substances and drugs
severe)
Acute alcohol overdose, phencyclidine
Trauma and Ischemia
(angel dust), other drugs,
Skeletal muscle injuries
especially with seizures
Crush injury, surgery
Carbon Monoxide, ethylene glycol
Severe exercise
Sea snake bite, hornet’s venom
Massive muscle ischemia
Diuretics causing hypokalemia
Cardiac muscle injury
Hereditary causes
Seizures from any cause
Paroxysmal (Meyer-Betz)
Heat cramps
Anesthesia, malignant hyperthermia
Infections
Phosphorylase deficiency (McArdle’s)
Influenza, Herpes virus
Carnitine Palmityl transferase deficiency
Epstein-Barr virus
in children
Legionnaires’ disease and other severe
Occassionally in glycogen and lipid
bacterial infections
Storage diseases with myopathies
Occasionally in periodic paralysis
The distinction between hemoglobinuria and myoglobinuria can be difficult to make on urine color
alone. Myoglobinuria should be considered if positive occult blood and protein tests on a reagent
dipstick are seen. A quantitative measurement should then follow to determine whether the heme
protein in the urine is hemoglobin or Myoglobin.
The detection of protein is based on the “protein error of pH indicators.” The indicator 3, 3, 5, 5
tetrachlorophenol-3, 4, 5, 6-tetrabromosulfophthalein used in this test is a more recent development. A
positive reaction is indicated by a color change from yellow to light green/green.
The chemical detection of blood is based on the strong pseudoperoxidase action of erythrocytes and
hemoglobin. The detection of blood in urine is based on the o-tolidine method by Leonards and further
developed. Hemoglobin and Myoglobin, if present, catalyze the oxidation of the indicator by the
organic peroxide contained in the test paper. Intact erythrocytes hemolyze on the test paper and
liberate hemoglobin that produces a green dot. Separate sets of color blocks are representative of
erythrocytes and hemoglobin. Scattered or compacted green dots on the yellow test paper are
indicative of intact erythrocytes.
Precautions:
Universal precautions should be maintained during testing. Gloves, shield, fluid-resistant lab coat
should be worn. Reagent dipsticks and controls are for in vitro diagnostic use only.
Storage and Stability:
Chemstrip 10 UA dipsticks should be stored at < 30  C (room temperature). Do NOT freeze. The vial
must be closed when not in use. Rapid deterioration of dipsticks due to moisture and light can occur is
vial uncapped for extended periods of time. Each vial is stable until expiration date printed on each
vial label.
Kova-trol I and III must be kept at 2 - 8  C and is stable until expiration date listed on each control
bottle. Reconstituted controls must be kept refrigerated and are stable for 7 days. Aliquots of controls
are stable up to 4 months when stored at –20  to –40 C. Do not shake roughly or expose to air or
light for excessive amounts of time.
Specimen Collection and Handling:
A freshly voided clean catch urine specimen or first-morning collected in a clean, sterile screw-capped
container may be used. At least, 20 ml of urine is required for screen and quantitative test if needed.
Specimen should be brought to lab within one hour. If unable to transport immediately, refrigerate
specimen at 2 – 8 C. Refer to the Specimen Collection SOP for details on collecting a urine specimen.
Materials Needed:
Plastic conical tube
Clean, sterile screw-capped container
Chemstrip 10 UA dipsticks/strips
Chemstrip 101 reader
Kova-Trol I
Kova-Trol III
Disposable paper towels
Quality Control:
Kova-Trol I and III are performed once per 24 hours usually on 3rd shift to verify reader and dipsticks
results are within acceptable ranges. Results are recorded on each controls individual control logsheet.
Procedure:
Automated:
1) Label a plastic conical tube with patient’s last name and first initial. Place in specimen rack.
2) Mix urine specimen gently. Open lid and pour 10-12 ml of urine into conical tube.
3) Press “start” on Chemstrip 101 reader.
4) Open Chemstrip 10 UA vial and remove 1 dipstick. Immerse entire dipstick into urine
specimen in conical tube.
5) Hold dipstick sideways against paper towel to allow excess urine specimen to drain.
6) Place dipstick into Chemstrip 101 reader pads facing upwards.
7) Press “start” to begin measurement. Results will print in approximately 60 seconds. Write
patient’s name and medical record, date of birth, or social security number onto printout.
8) Record results of the blood (BLO) and protein (PRO) tests onto patient’s miscellaneous result
form under “Urinalysis.”
9) Record results on Urinalysis Patient Log.
Manual/Visual:
1a) Label a plastic conical tube with patient’s last name and first initial. Place in specimen rack.
2a) Mix urine specimen gently. Open lid and pour 10-12 ml of urine into conical tube.
3a) Open Chemstrip 10 UA vial and remove 1 dipstick. Immerse entire dipstick into urine
specimen in conical tube.
4a) Hold dipstick sideways against paper towel to allow excess urine specimen to drain.
5a) Hold dipstick nest to the color blocks interpretation chart on side of Chemstrip 10 UA vial.
6a) Read Protein and Blood at 30 – 60 sec. Color changes are stable up to 120 sec after immersion
in urine specimen. Do not read color changes that only occur along the edges of the test pads.
7a) Record results of the blood (BLO) and protein (PRO) tests onto patient’s miscellaneous result
form under “Urinalysis.”
8a) Record results on Urinalysis Patient Log.
Results and Interpretation:
Positive for blood and protein, write in “Miscellaneous” area, “Myoglobin may be present,
quantitative urine Myoglobin to follow.” Order Myoglobin quantitative test and send to referral lab
for testing.
Negative for blood and/or protein, result as “Myoglobin screen is negative, no further testing
required.”
Protein: A color change from yellow to light green/green will occur if protein is present. The
concentrations given on the Chemstrip 10 UA vial label correspond with the albumin concentration in
urine. Pathological proteinuria will usually produce persistent values above 30 mg/dl.
Blood: Erythrocyte excretion up to 5 Ery/ul may be expected in normal urine. Levels above these
should be investigated further.
DIFFERENTIATION OF RED BLOOD CELLS, HEMOGLOBIN, AND MYGLOBIN IN URINE
FINDINGS
Reagent dipstick
Red blood cells in
sediment
Urine appearance
Plasma/serum
appearance
Total serum CK
RED CELLS
Positive
Present
HEMOGLOBIN
Positive
Absent (few)
MYOGLOBIN
Positive
Absent (few)
Cloudy Red
Normal
Clear Red
Pink to Red (hemolysis)
Clear Red-brown
Normal
Normal
Total serum LD
LD isoenzymes 1 and 2
LD isoenzymes 4 and 5
Normal
Normal
Normal
Slight elevation
(10x normal upper
limit)
Elevated
Elevated
Normal
Marked elevation
(40x normal upper
limit)
Elevated
Normal
Elevated
Limitations:
Blood:
False-positive Results:
1) Strong oxidizing cleaning agents such as chlorine beach cause false-positive results because of
oxidation of the chromogen in the absence of peroxide.
2) Microbial peroxidase activity associated with urinary tract infection may result in a positive
reaction.
3) Blood as a contaminant from menstruation will give positive results of no clinical significance.
False-negative Results:
1) Formalin used as a preservative, large amounts of nitrite (more than 10 mg/dl), and treatment
with captopril (an antihypertensive).
2) Elevated specific gravity (high salt concentration) and elevated protein levels may reduce the
lysis of red cells.
3) Testing the supernatant urine from centrifugation or settling when only; a few intact red cells
are present.
4) Ascorbic acid (generally more than 25 mg/dl) which is above the reasonable or normal levels.
Protein:
False-positive Results:
1) In strongly basic urine (pH 9 or higher).
2) During therapy with phenazopyridine.
3) When infusions of polyvinylpyrrolidone (blood substitutes) are administered.
4) When residues of disinfectants containing quaternary ammonium groups or chlorohexidine are
present in the urine container.
References:
1. Roche Diagnostics: Chemstrip 10 UA Package Insert, Roche Diagnostics, Indianapolis, IN.,
1999.
2. Hycor Biomedical: Kova-Trol: Human Urinalysis Controls Package Insert, Hycor Biomedical
LTD., Garden Grove, CA., 07/03.
3. Burtis, Carl A., Ashwood, Edward R.: Tietz Textbook of Clinical Chemistry, 2nd edition, pg
2085, 1994.
4. Ringsrud, Karen, Linne, Jean: Urinalysis and Boddy Fluids: A Colortext and Atlas, MosbyYear Book, Inc., St. Louis, MO., pg 55 – 57, 1995.
5. Henry, John: Clinical Diagnosis and Management by Laboratory Methods, 17th edition, W. B.
Saunders Co., Philadelphia, PA., pg 418 – 419, 1984.