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Effects of Hemolysis on Clinical Specimens

Hemolysis due to the breakdown of red blood cells is important to the laboratory because it can have an effect on laboratory results. The effects can be the result of products liberated from the red cells themselves, or due to interferences with laboratory analyzers. This may vary from one test to another depending on the formulation of the reagent.

Hemolysis can occur in vivo (in the patient), due to a variety of medical conditions, including antigen-antibody reactions, hemolytic anemias, toxins and poisons, mechanical RBC rupture due to artificial heart valves, as well as treatments such as hemodialysis and the use of the heart-lung bypass machine. Hemolysis can occur during suboptimal blood collection, or in vitro (e.g. in the collection tube) due to improper handling, transport, and storage.

The amount of hemolysis needed to affect a test is dependent on the test being performed. In general, slight hemolysis has little effect on most tests; however, it will cause increased test results for specific tests like potassium and lactate dehydrogenase (see table below). Samples with slight hemolysis are analyzed and the results reported with a comment indicating the degree of hemolysis and the effect on the test result. Grossly hemolyzed samples can affect the results of many tests; therefore, a recollection will be requested for most grossly hemolyzed samples.

Notable examples of tests affected by hemolysis are found in the table below.

Effect of Hemolysis on some Clinical Biochemistry and Hematology Test Results


Degree of change in analyte

Test result increased by hemolysis


Test result decreased by hemolysis

Test result increased or decreased by hemolysis

Slight change

Phosphate, Total Protein, Albumin, Magnesium, Calcium, Alkaline Phosphatase

Haptoglobin, Bilirubin


Noticeable change

Alanine Amino Transferase, Creatinine Kinase, Iron, Coagulation tests



Significant change

Potassium, Lactate Dehydrogenase, Aspartate Amino Transferase

Troponin T

Hemoglobin, Red Blood Cells, MCHC, Platelet Count



Note:  If the specimen is grossly hemolyzed, a recollected specimen will be requested. If the recollected specimen is also grossly hemolyzed, it will be processed and a comment added.