Heinz body anemia Flashcards
What is the prevalence of Heinz body anemia in cats compared to other species
Heinz body anemia is more commonly seen in cats compared to other species because of increased formation and decreased removal
Why cats are more commonly affected by Heinz body anemia
The hemoglobin of cats is particularly prone to oxidative damage because it contains a high number of free slufhydryl groups that are targets for this process
- cats have eight sulfhydryl groups, compared to dogs, that have four, and people, who have two, per hemoglobin molecule
Another reason why cats are particularly prone to oxidative damage is due to the fact that the natural anti-oxidant in RBCs, called glutathione, exists in low concentrations and is quickly consumed
Explain how Heinz bodies are formed
Oxidation of the sulfhydryl groups on the hemoglobin molecule results in the formation of disulfide bonds, which cause a conformational change to the hemoglobin
The denaturated hemoglobin precipitates into a “Heinz body”
What is the best staining to visualize Heinz bodies on a blood smear
Heinz bodies are not readily seen on Romanowsky-type stains (e.g., Diff Quick)
They can be seen on supravital stains such as New Methylene Blue
- the denaturated hemoglobin may clump to one side of the RBC producing an “eccentrocyte”
Why is it normal to see a low number of RBCs containing Heinz bodies (<5%) in cats
RBCs containing Heinz bodies are usually removed from the circulation by macrophages in the spleen
Unlike dogs, cats have a non-sinusoidal spleen which means that these RBCs are not as efficiently removed, thus a low number of RBCs containing Heinz bodies are usually present in normal cats
What could be the consequence of a marked oxidative damage in cats (for example paracetamol intoxication)
If oxidative damage is marked, Heinz body formation may be accompanied by oxidation of heme, resulting in the formation of methemoglobin, which cannot carry oxygen
Methemoglobin is a form of hemoglobin in which the iron in the heme group is in the ferric (Fe3+) rather than the ferrous (Fe2+) state
Significant methemoglobinemia is characterized by a dark bluish-chocolate color to the blood
Give some example of causes of diseases accompanied with excessive numbers of Heinz bodies
Paracetamol toxicity (usually with marked methemoglobinemia)
Consecutive day or prolonged CRI administration of propofol
Onion and garlic ingestion
Diabetic ketoacidosis
Other diseases increasing the oxidative stress (e.g., hyperthyroidism, lymphoma, hepatic lipidosis)
