Heinz body

Heinz bodies (also referred to as "Heinz-Ehrlich bodies") are inclusions within red blood cells composed of denatured hemoglobin.^[1][2]

History

They are named after Robert Heinz (1865-1924), a German physician who in 1890 described these inclusions in connection with cases of hemolytic anemia.^[3][4]

Form and appearance

Heinz body stain of feline blood showing three distinct heinz bodies.

Heinz bodies appear as small round inclusions within the red cell body, though when stained with Romanowsky dyes they may appear as projections from the cell. They appear more clearly when supravitally stained ^[5] (e.g., with methylene blue or bromocresyl green).

Etiology and associated disorders

Heinz bodies are formed by damage to the hemoglobin component molecules, usually through oxidations, or the a change of an internal amino acid residue(from an inherited mutation), which causes the damaged molecules to, often degrade and the precipitate, damaging the cell membrane by hydrophobically adsorbing to it thereby increasing cell permeability, leading to premature cell lysis.^[6] Damaged cells are attacked by macrophages in the spleen, where the precipitate and damaged membrane are removed, leading to characteristic "bite cells". The denaturing process is irreversible and the continual elimination of damaged cells leads to Heinz body anemia.

There are several pathways leading to the hemoglobin damage.

• In α-thalassemia, lack of α subunits causes β subunits to form tetramers which precipitate out of solution, creating Heinz bodies.
• G6PD (Glucose-6-Phosphate Dehydrogenase) deficiency brought on by administration of oxidant drugs (e.g., primaquine) also can result in Heinz bodies.
• Heinz bodies can also be found in chronic liver disease.^[7]

Veterinary

In veterinary medicine Heinz bodies are associated with the consumptions of onions by cats,^[8] dogs, and various primates, and a symptom of paracetamol poisoning in cats. Thiosulfate compounds in the flesh of onions have been identified as the cause.

Propylene glycol was once a common ingredient in soft moist cat food. According to the FDA "It was known for some time that propylene glycol caused Heinz Body formation in the red blood cells of cats (small clumps of proteins seen in the cells when viewed under the microscope), but it could not be shown to cause overt anemia or other clinical effects. However, recent reports in the veterinary literature of scientifically sound studies have shown that propylene glycol reduces the red blood cell survival time, renders red blood cells more susceptible to oxidative damage, and has other adverse effects in cats consuming the substance at levels found in soft-moist food.^[9] In light of this new data, CVM amended the regulations to expressly prohibit the use of propylene glycol in cat foods."^[10]

Treatment

There is no specific treatment for Heinz bodies; however they are important as a diagnostic indicator for the causative conditions listed above.

References

External links

• Heinz Bodies: Photo at University of Virginia