Oxidative haemolysis due to ‘poppers’

Abstract

A 38-year-old man was admitted to hospital with several days of malaise and dyspnoea. He was on no prescribed medications, and had previously been well apart from an episode of gangrenous cholecystitis due to mixed gallstones three years previously. Full blood examination showed haemoglobin 110 g/l, white cell count 12AE9 · 10/l with neutrophil count 9AE2 · 10/l, and platelet count 266 · 10/l. The blood film (left) demonstrated marked polychromasia with features of oxidative haemolysis and hyposplenism. Supravital staining with methyl-violet demonstrated numerous Heinz bodies (top right). Other indicators of haemolysis included a reticulocytosis of 241 · 10/l, lactate dehydrogenase 374 IU/l, bilirubin 54 lmol/l with undetectable haptoglobin and a negative direct antiglobulin test. On further enquiry, the patient denied fava bean ingestion but disclosed heavy recreational use of inhalational amyl nitrite. Avoidance of further nitrite exposure resulted in resolution of haemolysis, and the patient was provided with counselling on drug use. Laboratory testing in the convalescent phase did not detect evidence of glucose-6-phosphate dehydrogenase deficiency or an underlying haemoglobinopathy. Nitrite inhalants, such as amyl nitrite, are highly volatile yellow liquids that cause rapid vasodilation and hence were once used as anti-anginals. Nitrites efficiently oxidize haemoglobin to methaemoglobin and may also increase the proteolytic susceptibility of haemoglobin leading to globin chain denaturation and Heinz body formation. The recreational use of alkyl nitrites, colloquially known as ‘poppers’ (bottom right), should be considered in apparently idiopathic episodes of oxidative haemolysis. Significant complications may occur even in patients with intact red cell reduction pathways.