Note the RBC's with Heinz Bodies present (Nile Blue Sulfate stain)
In the normal physiological activity of the RBC the following occurs:
If oxidation of heme iron occurs by any of the following:
- » Auto-oxidation of long standing,
- » Ferricyanide reaction,
- » Nitrates or nitrites,
- » Sulfonamides,
Then this creates a ferric state of heme iron (Fe+++) and it cannot bind to nor transport O2.This new state of hemoglobin is not methemoglobin. As the RBC ages, the level of G6PD decrease to deficient levels. This reduction occurs over 120 day period, at which time the aging RBC’s are removed from circulation. If there is a deficiency or absence of G6PD, the RBC aging process is faster.
Clinical symptoms for the most individual with variants of G6PD deficiency are absent. These lead normal lives, experiencing mild to moderate anemia conditions are generally asymptomatic. The variants of G6PD that are defective and subject to significant hemolytic episodes, the patient will experience: headaches, dizziness, palpations, dyspnea, abdominal pain, and back pain. Expected clinical laboratory findings include:
-  Hemoglobinuria (with brown to black colored urine).
 If severe episode, a hemoglobin drop of 3 to 4 gm/dL.
 Hemoglobinemia (with pink to brown plasma).
 Reticulocyte count = 8 to 12 %
 Bilirubin = >1.5 mg/dL
 Haptoglobin = < ldh =" ">200 IU/L with LDH-1 and LDH-2 as the predominant isoenzyme forms
 Peripheral blood smear will contain  bites cells, [b] spherocytes, [c] cell fragments, [d] blister cells, [e] Heinz bodies, [f] polychromasia, and [g] poikilocytosis
 Urobilinogen = increased
Specific hematological tests useful in diagnosing G6PD deficiency are:
-  Ascorbate Cyanide Test. This is a sensitive test, but not very specific. Its principle is based upon the absence of G6PD in the RBC and the failure to reduce H2O2.
-  Fluorescent Spot Test. This is a testing principle in which glucose-6-phosphate, NADP, and saponin is added to whole blood. If G6PD is present, then NADP is converted to NADPH. NADPH will fluoresce if present.
-  Methemoglobin Reductase Test. This is a screening test that uses fresh whole blood, NADPH, and methylene blue. The principle is based up the reduction of methemoglobin to hemoglobin by NADPH. G6PD deficient RBC lack this ability. Caution. This test needs to be performed immediately after collecting the blood. If blood is allowed stand for too long a period of time, a false positive may result.