Test Catalog

Test ID: UNHB    
Hemoglobin Stability, Blood

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

Work-up of congenital hemolytic anemias

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

Unstable hemoglobin disease is rare and may be caused by any 1 of a large number of hemoglobin variants. They are inherited as an autosomal dominant trait. The severity of the disease varies according to the hemoglobin variant; there may be no clinical symptoms or the disease may produce a mild, moderate, or severe hemolytic anemia.


The stained peripheral blood smear shows anisocytosis, poikilocytosis, basophilic stippling, polychromasia and, sometimes, hypochromia. The reticulocyte count may be increased. Splenomegaly and Heinz bodies may also be present.

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.

Only orderable as part of a profile or as a reflex. For more information see:

-HAEV1 / Hemolytic Anemia Evaluation, Blood

-HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood

-THEV1 / Thalassemia and Hemoglobinopathy Evaluation, Blood

-REVE1 / Erythrocytosis Evaluation, Whole Blood

-MEV1 / Methemoglobinemia Evaluation, Blood


Normal (reported as normal [stable] or abnormal [unstable])

Interpretation Provides information to assist in interpretation of the test results

An abnormal or unstable result is indicative of a hemoglobin variant present. Other confirmatory tests should be performed to identify the hemoglobinopathy (HBEL1 / Hemoglobin Electrophoresis Cascade, Blood).

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

False-positive results will be obtained in blood specimens containing greater than 5% fetal hemoglobin or in specimens greater than 1 week old.

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

1. Hoyer JD, Hoffman DR: The thalassemia and hemoglobinopathy syndromes. In: McClatchey KD, Amin HM, Curry JL, eds. Clinical Laboratory Medicine. 2nd ed. Lippincott Williams and Wilkins; 2002:866-895

2. Benz EJ, Ebert BL: Hemoglobin variants associated with hemolytic anemia, altered oxygen affinity, and methemoglobinemias. In: Hoffman R, Benz EJ, Silberstein LE, et al: eds. Hematology: Basic Principles and Practice. 7th ed. Elsevier; 2018:608-615