Serum Myoglobin Test for Rhabdomyolysis
The serum myoglobin level (SMB) is a measure of the amount of hemoglobin present in blood plasma. Hemoglobin is a protein found primarily in red blood cells. A normal level of hemoglobin in blood plasma indicates adequate oxygen supply to all body tissues and organs.
In patients with rhabdo, however, there may not be enough available oxygen to sustain life or other vital functions such as breathing. The presence of too much hemoglobin in blood plasma causes the patient’s condition to deteriorate rapidly.
Rhabdo occurs when the body breaks down muscle tissue into its constituent parts, which are then released from the damaged muscles into the bloodstream. These released components include large amounts of waste products called metabolites. Metabolites can damage or destroy healthy tissues if they accumulate in sufficient quantities.
When these toxins do so, they produce toxic effects in the human body.
In addition to causing severe damage to the heart and kidneys, some of these metabolites can cause kidney failure. Other harmful effects associated with rhabdo include:
Fluid buildup in the lungs (pulmonary edema). Pulmonary edema is fluid accumulation within the lungs due to excessive fluid loss from damaged lung tissue. If left untreated, pulmonary edema can lead to death.
Loss of blood into the urine (hematuria).
Metabolic acidosis, which is a condition that occurs when the acidity of bodily fluids falls out of normal range. Metabolic acidosis can cause headache, confusion, muscle pain, and rapid heart rate.
Serious health consequences of rhabdo may also include:
Serum myoglobin test is performed to measure the level of myoglobin in the patient’s blood plasma. The most common method for measuring myoglobin is through a blood test. During this procedure, the patient’s blood is drawn from a vein and sent to a medical lab for analysis.
It typically takes two to four hours to receive test results from a clinical lab.
Health care providers may order a second test to confirm the presence of myoglobin if the initial results are negative. This additional testing will provide a more accurate result. A serum myoglobin test is not typically painful and it does not pose any serious health risks.
If the patient has an iron deficiency or another condition that causes low levels of hemoglobin in the blood, the lab report may incorrectly identify low myoglobin levels as the cause of concern.
There are several conditions that can lead to a false positive myoglobin test result. A few of these instances include:
Severe muscle trauma or injury.
Serious burns or sunburns.
Serious infections or infestations of the skin.
Some heavy metal poisoning, such as lead poisoning.
Tropical sprue, which is a condition marked by malnutrition and vitamin B12 deficiency.
While some of these conditions may be serious, they do not normally cause life-threatening symptoms. Other causes of false-positive test results include:
An injection of a dye called ink or india ink into the veins around three to five days before the myoglobin test.
Heavy cigarette smoking within two to three days before the blood test.
The use of antacids within 48 hours before the blood draw.
The use of laxatives within 24 hours before the blood draw.
A severe trauma or accident within 48 hours before the blood draw.
The use of some medicines, such as Adderall, aminophylline, or theophylline.
Some diseases or disorders that may cause a false negative myoglobin test result are:
Diabetic ketoacidosis (DKA), which is a serious complication of diabetes.
Early stages of kidney failure.
Liver failure or liver disease.
Pancreatitis, which is an inflammatory disease of the pancreas.
Some types of anemia, such as sickle cell anemia.
Serious long-term nicotine or alcohol use can also cause a false negative test result.
A urinalysis can be done to check for the presence of hemoglobin or myoglobin within the urine.
Treatment for rhabdomyolysis typically involves supportive care and treatment of the underlying cause of the condition. Treatment for severe muscle damage may require admission to an intensive care unit. During treatment, doctors will work to correct any abnormal biochemical processes that may be contributing to the condition.
This may involve the use of agents that reduce high levels of certain chemicals in the blood and increased hydration through an intravenous line.
The myoglobin test is used to detect the presence of myoglobin in the blood. Myoglobin is a protein that binds to and carries oxygen in muscle tissue. When muscles experience trauma or are damaged, they may release myoglobin into the bloodstream.
While myoglobin is normally cleared from the blood within a few hours, high levels can indicate damage to muscle tissue and potentially be an indicator of rhabdomyolysis.
The myoglobin test is typically part of a group of tests used to detect evidence of muscle damage. These tests may also include a creatine kinase (CK) test and a serum myoglobin (SMB) test. A blood urea nitrogen (BUN) test may also be used as part of the evaluation.
A myoglobin test is usually performed on a blood sample. However, in some cases, the urine may be used instead. A positive myoglobin test does not necessarily mean that a person has rhabdomyolysis.
It may be an indicator that further tests should be done to confirm whether or not the condition is present. Additionally, while a negative myoglobin test result does rule out the condition, it does not necessarily mean that the individual is free of muscle damage.
Test code: 7013T
CPT Code: 83530 (quantitative)
Turnaround time for this test is currently at 5 days. Should you require a test of this nature sooner, contact Client Services at 1.800.456.2350 for details.
Sources & references used in this article:
Serum myoglobin level as diagnostic test in patients with acute myocardial infarction. by MJ Stone, MR Waterman, D Harimoto, G Murray… – Heart, 1977 – heart.bmj.com
The value of serum myoglobin determinations in the early diagnosis of acute myocardial infarction by LE Roxin, I Cullhed, T Groth, T Hällgren… – Acta Medica …, 1984 – Wiley Online Library
Radioimmunoassay of myoglobin in human serum. Results in patients with acute myocardial infarction. by MJ Stone, JT Willerson… – The Journal of …, 1975 – Am Soc Clin Investig