M WAINSTEIN1,2, W JAMES2
1Royal Darwin Hospital, Darwin, Northern Territory; 2Lismore Base Hospital, Lismore, New South Wales
Background: Glucose-6-phophate dehydrogenase (G6PD) is a key enzyme in the pentose-phosphate pathway which protects cells from oxidative stress. Exposure to such stress in patients with G6PD deficiency can lead to intravascular haemolysis and acute kidney injury which is generally self-limiting with resolution of the haemolytic episode. The pathogenesis of kidney injury in this condition is thought to be driven by haem pigment-induced tubular cytotoxicity, obstruction and vasoconstriction. We present the case of a patient with severe G6PD deficiency and mild but progressive kidney disease attributed to chronic haemolysis.
Case Report: A 68 year-old Philipino woman was referred to clinic with a creatinine of 126 umol/L and eGFR 34 ml/min which had declined from 48 ml/min four years earlier. Her medical history was significant for G6PD deficiency with severe enzyme deficiency (7%) but no overt haemolytic episodes, myelodysplastic syndrome, iron deficiency anaemia and hypertension. She admitted to infrequent use of NSAIDs and medicinal herbs. Investigations revealed a haemoglobin of 89 g/L with evidence of haemolysis (LDH 1702 u/L, Haptoglobin 0.2 g/l and Bilirubin 35 umol/L) as well as iron deficiency. Urine showed a trace of protein and a bland sediment. A renal biopsy showed marked amounts of intracytosplasmic haemosiderin in the tubules, mild tubulointerstitial fibrosis and normal glomeruli. When evaluating LDH levels and renal function over the past four years, no correlation was found to indicate an episodic pattern. The patient was treated supportively, advised to stop taking NSAIDs and herbs and avoid pro-oxidative drugs in the future.
Conclusions: Patients with severe G6PD deficiency and chronic, subclinical, haemolysis are at risk of chronic kidney disease from prolonged exposure to haem pigment and its nephrotoxic effects.