Glucose-6-phosphate dehydrogenase deficiency

Injury	Disease	Nutrition	Poison

Symptoms	Surgery	Test	Special Topic

Blood cells

Glucose-6-phosphate dehydrogenase deficiency

Definition:

G-6-PD deficiency is a hereditary, sex-linked enzyme defect that results in the breakdown of red blood cells when the person is exposed to the stress of infection or certain drugs.

Alternative Names:

G-6-PD deficiency; Hemolytic anemia due to G6PD deficiency; Anemia - hemolytic due to G6PD deficiency

Causes, incidence, and risk factors:

G-6-PD deficiency is an inheritable, X-linked recessive disorder whose primary effect is the reduction of the enzyme G-6-PD in red blood cells, causing destruction of the cells, called hemolysis. Ultimately, this hemolysis leads to anemia -- either acute hemolytic or a chronic spherocytic type.

In the United States, many more black than white people have the disorder. Approximately 10-14% of the black male population is affected. The disorder may occasionally affect a black women to a mild degree (depending on their genetic inheritance).

People with the disorder are not normally anemic and display no evidence of the disease until the red blood cells are exposed to an oxidant or stress.

Drugs that can bring on this reaction include:

antimalarial agents
sulfonamides (antibiotic)
aspirin
nonsteroidal anti-inflammatory drugs (NSAIDs)
nitrofurantoin
quinidine
quinine
others

It can also be caused by exposure to certain chemicals, such as those in mothballs. The chronic spherocytic anemia is unaffected by exposure to these drugs.

The risk of acute hemolytic crisis can be decreased by reviewing the family history for any evidence of hemolytic anemias or spherocytosis or testing before giving any medications belonging to the above class of chemicals.

The episodes are usually brief, because newly produced (young) red blood cells have normal G6PD activity.

Risk factors are being black, being male, or having a family history of G6PD deficiency. Another type of this disorder can occur in whites of Mediterranean descent. This form is also associated with acute episodes of hemolysis. Episodes are longer and more severe than in the other types of the disorder.

Symptoms:

Note: Severe hemolysis may cause hemoglobinuria (hemoglobin in the urine).

Signs and tests:

Anemia
Hemolysis
Reduced G-6-PD activity
Reticulocytosis following a hemolytic crisis

Tests include:

Elevated bilirubin levels
Elevated serum LDH
Low serum haptoglobin
Hemoglobin in the urine
Elevated absolute reticulocyte count
Low red blood cell count and hemoglobin
Heinz bodies present on examination of the peripheral blood smear using special stains
Methylene blue test
Methemoglobin reduction test

Treatment:

If the cause is an infection, it should be treated. If the cause is a drug, the offending agent should be stopped. People with the Mediterranean form, or those in hemolytic crisis may occasionally require transfusions.

Expectations (prognosis):

Spontaneous recovery from hemolytic crises is the usual outcome.

Complications:

Rarely, kidney failure or death may occur following a severe hemolytic event.

Calling your health care provider:

Call for an appointment with your health care provider if symptoms of hemolytic anemia due to G-6-PD deficiency develop.

Call your health care provider if you have G-6-PD deficiency and symptoms of hemolytic anemia do not disappear after treatment of the cause.

Prevention:

People with G-6-PD must strictly avoid factors that can precipitate an episode, especially drugs known to cause oxidative reactions.

Genetic counseling or genetic information may be of interest to heterozygous women and affected men.

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