Heinz Body Anaemia

Heinz body anaemias

Summary
Cause:	Oxidative injury to erythrocytes
Associated conditions:	Exposure to oxidative toxins
Differential diagnoses:	Other causes of anaemia
Diagnosis:	Examination of blood smears
Treatment:	Supportive

Introduction

Heinz bodies are inclusion bodies that form within erythrocytes as a result of oxidative injury to the cell. Named after Robert Heinz, the German physician who first described them, they consist of precipitated haemoglobin and their presence can result in premature phagocytosis of erythrocytes

Pathophysiology

Structure of haemoglobin

Haemoglobin is a conjugated protein consisting of four globin chains, each of which contains a heme group. Its structure allows it to combine reversibly with oxygen and is thus very important in the transportation of oxygen to tissues. Normally the iron within the heme group is in the ferrous (2+) form, the form able to combine with oxygen.

Oxidative damage to haemoglobin

Erythroctyes are constantly exposed to oxidants both physiological and pathological. Oxidation results in three major changes to the haemoglobin molecules:

• Heinz bodies are produced when the sylfhydral groups in the globin part of the haemoglobin molecule undergoes oxidation, causing the molecule to become unstable. Heinz bodies are formed when the damaged haemoglobin molecules coalesce.

• Methaemoglobinaemia formation occurs when the iron in the haemoglobin molecule is oxidised to the ferric (3+) state. In normal circumstances the methaemoglobin reductase enzyme reduces ferric (3+) back to ferrous (2+) but this system can become overwhelmed in some circumstances.

• Eccentrocytes

Substances causing Heinz body formation

Cats, dogs, horses and ruminants can all suffer from Heinz body anaemias but they are clinically significant mainly in the cat and dog.

Cats

Feline erythrocytes are particularly susceptible to oxidative damage because they have eight highly reactive sulfhydryl groups, as opposed to two less reactive ones in other species.