Test Catalog

Test ID: A2M    
Alpha-2-Macroglobulin, Serum

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

Evaluation of patients with nephrotic syndrome and pancreatitis

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

Alpha-2-macroglobulin is a protease inhibitor and is one of the largest plasma proteins. It transports hormones and enzymes, exhibits effector and inhibitor functions in the development of the lymphatic system, and inhibits components of the complement system and hemostasis system.


Increased levels of alpha-2-macroglobulin are found in nephrotic syndrome when other lower molecular weight proteins are lost and alpha-2-macroglobulin is retained because of its large size. In patients with liver cirrhosis and diabetes, the levels are found to be elevated.


Patients with acute pancreatitis exhibit low serum concentrations, which correlate with the severity of the disease. In hyperfibrinolytic states, after major surgery, in septicemia, and severe hepatic insufficiency, the measured levels of alpha-2-macroglobulin are often low. Acute myocardial infarction patients with low alpha-2-macroglobulin have been reported to have a significantly better prognosis with regard to the greater than a year survival time.

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 =18 years: 178-495 mg/dL

>18 years: 100-280 mg/dL

Interpretation Provides information to assist in interpretation of the test results

Values are elevated in the nephrotic syndrome in proportion to the severity of protein loss (lower molecular weight).  


Values are low in proteolytic diseases such as pancreatitis.

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

Quantitation of specific proteins by nephelometric means may not be possible in lipemic sera due to the extreme light scattering properties of the specimen. Turbidity and particles in the specimen may result in extraneous light scattering signals, resulting in variable specimen analysis.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. McMahon MJ, Bowen M, Mayer AD, Cooper EH: Relation of alpha-2-macroglobulin and other antiproteases to the clinical features of acute pancreatitis. Am J Surg. 1984;147:164-170

2. Haines AP, Howarth D, North WR, et al: Haemostatic variables and the outcome of myocardial infarction. Thromb Haemost. 1983;50:800-803

3. Hofmann W, Schmidt D, Guder WG, Edel HH: Differentiation of hematuria by quantitative determination of urinary marker proteins. Klin Wochenschr. 1991;69:68-75

4. Solerte SB, Adamo S, Viola C, et al: Acute-phase protein reactants pattern and alpha 2 macroglobulin in diabetes mellitus. Pathophysiological aspects in diabetic microangiopathy. La RIC Clin Lab. 1994;14:575-579

5. Silverman LM, Christenson RH, Grant GH: Basic chemistry of amino acids and proteins. In: Tietz, NW ed. Clinical Guide to Laboratory Tests. 2nd ed. WB Saunders Comp; 1990:380-381

6. Rafai N, Horvath AR, Wittwer CT, eds: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018