Condensed Case

A 2-year-old African American boy was seen in the sick baby clinic with vomiting, fever, and red-colored urine staining his diapers. His initial lab results showed hemoglobin of 5 g/dL and hematocrit of 15%. The most remarkable chemistry value was an LDH of 500 IU/L (reference range, 0 to 100 IU/L), which is extremely elevated. His peripheral smear revealed polychromasia and occasional bite cells.

When the mother was questioned as to whether the baby had ingested anything out of the ordinary, she stated that the baby has been chewing on mothballs in her closet. The baby was transported to the intensive care unit. What is happening to the baby?

Answer

The baby is suffering from severe intravascular lysis as evidenced by the LDH value and the extremely low hemoglobin and hematocrit. Most likely, the baby has G6PD deficiency brought on by chewing on naphthalene, the active ingredient of mothballs. Naphthalene is an oxidizing drug and in this case has put the baby's red cells under oxidant stress. Occasional bite cells in the smear suggest the formation of Heinz bodies and their subsequent removal by the spleen.

Summary Points

• The spleen plays a vital role in red cell health and longevity

• HS is an autosomal dominant disorder of several membrane proteins, the key protein being spectrin.

• Spherocytes are less deformable and are more osmotically fragile.

• Patients with hereditary spherocytes show splenomegaly, jaundice, and increased tendency for gallstone disease.

• The osmotic fragility test is a labor intensive but valuable test to assess red cell viability in different hypotonic salt solutions.

• HE is a membrane disorder of spectrin showing decreased thermal stability.

• There are several clinical variants of HE, including common HE, Southeast Asian ovalocytosis, and spherocytic HE.

• Hereditary pyropoikilocytosis is a recessive membrane disorder with a bizarre red cell morphology that shows hemoglobin budding.

• Hereditary stomatocytosis is a membrane disorder in which red cells have an intrinsic defect to sodium and potassium permeability.

• G6PD deficiency is the most common enzyme deficiency in the world.

G6PD is an X-linked recessive disorder with over 400 variants.

The drug- or infection-induced hemolysis in G6PD is intravascular, brisk, and self-limiting.

Most individuals with G6PD deficiency are totally unaware of their hematological condition until they are challenged by a drug that produces oxidant stress.

Pyruvate kinase deficiency is a enzyme deficiency of the Embden-Meyerhof pathway.

Aplastic anemia is a hypoproliferative disorder in which there is cellular depletion and a reduced production of blood cells.

Fanconi's anemia and Diamond-Blackfan syndromes are rare hypoproliferative disorders with congenital malformations.

PNH is a hemolytic anemia that is caused when nine red cell surface proteins are absent and red cells become increasingly sensitive to complement lysis.

CAS is a disease of the elderly and caused by an IgM autoantibody of wide thermal range. Paroxysmal cold hemoglobinuria is an extremely rare hemolytic disorder caused by anti-P of a wide thermal range.

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