Hemoglobin molecules in red blood cells transport and distribute oxygen to cells throughout the body. Hemoglobin is composed of heme - the portion of the molecule holding iron—and globin—a protein made up of amino acid chains.
Hemoglobin variants occur when mutations in the globin genes result in changes in the amino acids of the globin protein. Hundreds of variants have been identified; a small number of variants are common and have clinical significance. Hemoglobin variants are inherited in an autosomal recessive manner.
Effect of Hemoglobinopathies on A1C Test Results
With some assay methods, A1C tests in patients with hemoglobinopathies answer in falsely high outcomes, overestimating actual average blood glucose levels for the previous 2 to 3 months. Physicians may then dicate more aggressive treatments, resulting in increased episodes of hypoglycemia. Some assay methods used with some hemoglobinopathies may result in falsely low outcomes, leading to under-treatment of diabetes. Confirmation with a fasting blood glucose is needed for a diagnosis of diabetes to prevent inappropriate treatment decisions.
When to Suspect that a Patient with Diabetes Has a Hemoglobinopathy
People who contain one gene for a hemoglobinopathy are often unaware. Several situations may show the presence of a hemoglobinopathy:
* when results of self-blood-glucose monitoring have a low correlation with A1C results
* when an A1C result is vary than expected
* when an A1C result is more than 15 percent
* when a patient’s A1C test result is radically different from a previous test result following a change in laboratory A1C methods
Diagnosis of Hemoglobinopathies
Carrier state can easily be found by hemoglobin electrophoresis. Most states now screen for common hemoglobin variants in newborns and report results. In addition, pre-pregnancy genetic testing and prenatal screening are done in some high-risk populations or in women with a family history of a variant. Screening may also be acted in parents of children with identified variants and patients with red blood cell abnormalities, such as unexplained anemia.