Davis's Lab & Diagnostic Tests
Hemoglobin Electrophoresis and Abnormal Hemoglobins
General
Synonym/Acronym:
Hemoglobin F (fetal hemoglobin), hemoglobin S (sickle cell test), methemoglobin (hemoglobin M, MetHb, Hgb M).
Rationale
To assist in evaluating hemolytic anemias and identifying hemoglobin variants, diagnose thalassemias and sickle cell anemia. To assess for cyanosis and hypoxemia associated with pathologies affecting hemoglobin.
Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.
Normal Findings
Method: Electrophoresis for hemoglobin (Hgb) electrophoresis. Spectrophotometry for methemoglobin. Hemoglobin high-salt solubility for sickle cell screen.
| Hgb A | |
|---|---|
| Adult | Greater than 95% |
| Hgb A2 | |
| Adult | 1.5%–3.7% |
| Hgb C | None |
| Hgb D | None |
| Hgb E | None |
| Hgb F | |
| Newborns and infants | |
| 1 day–3 wk | 70%–77% |
| 6–9 wk | 42%–64% |
| 3–4 mo | 7%–39% |
| 6 mo | 3%–7% |
| 8–11 mo | 0.6%–2.6% |
| Adult–older adult | Less than 2% |
| Hgb H | None |
| Methemoglobin (Hgb M) | Less than 1% of total Hgb |
| Hgb S (sickle cell screen) | None (negative screen) |
Critical Findings and Potential Interventions
Methemoglobin
Cyanosis can occur at levels greater than 10%.
Dizziness, fatigue, headache, and tachycardia can occur at levels greater than 30%.
Signs of central nervous system depression can occur at levels greater than 45%.
Death may occur at levels greater than 70%.
Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.
Possible interventions include airway protection, administration of oxygen, monitoring neurological status every hour, continuous pulse oximetry, hyperbaric oxygen therapy, and exchange transfusion. Administration of activated charcoal or gastric lavage may be effective if performed soon after the toxic material is ingested. Emesis should never be induced in patients with no gag reflex because of the risk of aspiration. Methylene blue may be used to reverse the process of methemoglobin formation, but it should be used cautiously when methemoglobin levels are greater than 30%. Use of methylene blue is contraindicated in the presence of glucose-6-phosphate dehydrogenase deficiency.
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