Diagnostic Evaluation of Anemia: Hemolysis Workup and Direct Coombs Test

Anemia is a common hematological disorder characterized by a reduced red blood cell (RBC) count or hemoglobin level, leading to decreased oxygen delivery to tissues. Among the various causes of anemia, hemolysis—destruction of RBCs—plays a significant role. A comprehensive hemolysis workup helps identify underlying etiologies, guiding appropriate management strategies.

Understanding Hemolysis

Hemolysis refers to premature RBC destruction, which can occur intravascularly or extravascularly. Various conditions, including autoimmune disorders, infections, and hereditary abnormalities, contribute to hemolytic anemia.

Hemolysis Workup

Laboratory Tests

Complete Blood Count (CBC): Evaluates hemoglobin levels, RBC indices, and reticulocyte count.
Peripheral Blood Smear: Detects RBC morphology changes, such as spherocytes or schistocytes.
Lactate Dehydrogenase (LDH): Elevated in hemolysis due to RBC destruction.
Haptoglobin: Decreased levels suggest intravascular hemolysis.
Bilirubin Levels: Unconjugated bilirubin increases with hemolysis.
Urinalysis: Hemoglobinuria and hemosiderinuria may be present.

Specialized Tests

Direct Coombs (Direct Antiglobulin) Test: Identifies autoimmune hemolytic anemia by detecting antibodies or complement on RBCs.
Flow Cytometry: Used to diagnose paroxysmal nocturnal hemoglobinuria.
Enzyme Assays: G6PD deficiency testing if enzyme dysfunction is suspected.

Role of the Direct Coombs Test

The Direct Coombs test helps diagnose immune-mediated hemolysis by detecting bound immunoglobulins or complement proteins on RBCs. A positive result suggests an immune mechanism underlying hemolytic anemia, warranting further evaluation and treatment.