abnormality in this disorder is in the G-6-PD gene; this gene produces an
enzyme within the RBC that is essential for mem-brane stability. A few patients
have inherited an enzyme so defec-tive that they have a chronic hemolytic
anemia; however, the most common type of defect results in hemolysis only when
the RBCs are stressed by certain situations, such as fever or the use of
certain medications. The disorder came to the attention of researchers during
World War II, when some soldiers developed hemolysis while taking primaquine,
an antimalarial agent. African Ameri-cans and people of Greek or Italian origin
are those primarily af-fected by this disorder. The type of deficiency found in
the Mediterranean population is more severe than that in the African Caribbean
population, resulting in greater hemolysis and some-times in life-threatening
anemia. All types of G-6-PD deficiency are inherited as X-linked defects;
therefore, many more men are at risk than women. In the United States, about
12% of African American males are affected. The deficiency is also common in
those of Asian ancestry and in certain Jewish populations.
that have hemolytic effects for people with G-6-PD deficiency are oxidant
drugs. These medications include antimalarial agents (eg, chloroquine
[Aralen]), sulfonamides (eg, trimethoprim and sulfamethoxazole [Septra]),
nitrofurantoin (eg, Macrodantin), common coal tar analgesics (including aspirin
in high doses), thiazide diuretics (eg, hydrochlorothiazide [Hydro-DIURIL],
chlorothiazide [Diuril]), oral hypoglycemic agents (eg, glyburide [Micronase],
metformin [Glucophage]), chloram-phenicol (Chloromycetin), and vitamin K
(phytonadione [Aqua-Mephyton]). In affected people, a severe hemolytic episode
can result from ingestion of fava beans.
are asymptomatic and have normal hemoglobin levels and reticulocyte counts most
of the time. However, several days after exposure to an offending medication,
they may develop pal-lor, jaundice, and hemoglobinuria (hemoglobin in the
urine). The reticulocyte count rises, and symptoms of hemolysis develop.
Spe-cial stains of the peripheral blood may then disclose Heinz bodies
(degraded hemoglobin) within the RBCs. Hemolysis is often mild and
self-limited. However, in the more severe Mediterranean type of G-6-PD
deficiency, spontaneous recovery may not occur and transfusions may be
diagnosis is made by a screening test or by a quantitative assay of G-6-PD.
treatment is to stop the offending medication. Transfusion is necessary only in
the severe hemolytic state, which is more com-monly seen in the Mediterranean
variety of G-6-PD deficiency.
patient should be educated about the disease and given a list of medications to
avoid. If hemolysis does develop, nursing inter-ventions are the same as for
hemolysis from other causes.