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Test ID: MYGLU    
Myoglobin, Urine

Useful For Suggests clinical disorders or settings where the test may be helpful

Confirming the presence of a myopathy associated with any 1 of the disorders listed in Clinical Information

 

May suggest a myopathic cause for acute renal failure

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Myoglobin is the oxygen-binding protein of striated muscle. Injury to skeletal or cardiac muscle results in the release of myoglobin. High concentrations appear very rapidly in the urine in various conditions including some metabolic diseases.

 

Conditions associated with myoglobinuria include:

-Hereditary myoglobinuria

-Phosphorylase deficiency

-Sporadic myoglobinuria

-Exertional myoglobinuria in untrained individuals

-Crush syndrome

-Myocardial infarction

-Myoglobinuria of progressive muscle disease

-Heat injury

 

Urine myoglobin increases with muscle necrosis, but the clinical consequences are variable. Therefore, myoglobin can confirm a clinical diagnosis of myopathy, but an elevated urine excretion of myoglobin is not specific for a clinical disorder.

 

In acute renal failure, an elevated urinary myoglobin can suggest a potential cause and, consequently, may indicate appropriate treatment courses.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

< or =21 mcg/L

Interpretation Provides information to assist in interpretation of the test results

Increased excretion of urinary myoglobin suggests the disorders listed in Clinical Information.

 

Most clinically significant elevations are elevated 2 to 10 times normal.

 

Visual pigmenturia occurs at myoglobin concentrations about 160 times normal (approximately 4,000 mcg/L).

 

Renal toxicity depends on multiple factors such as renal perfusion and degree of acidity of urine.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

An elevated level of myoglobin in urine does not identify the clinical disorder.

 

Urine collected with acid as preservative will not be valid because acid interferes with analyte integrity.

 

Urinary myoglobin deteriorates rapidly unless stabilized immediately after collection by alkalizing with Na2CO3.

 

Urinary myoglobin does not withstand freezing even when pH is raised with Na2CO3.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Rowland LP: Myoglobinuria. Can J Neurol Sci 1984;11:1-13

2. Tonin P, Lewis P, Servidei S, DeMauro S: Metabolic causes of myoglobinuria. Ann Neurol 1990;27:181-185