Young man with cola-coloured urine, jaundice, pallor and back pain 2 days after starting primaquine (or dapsone, nitrofurantoin, fava beans, or an infection)
Red flags
Haemoglobinuria with falling urine output
Hb <70 g/L
Cyanosis with a normal PaO₂ (methaemoglobinaemia)
Neonate or infant (kernicterus)
Differential diagnosis
Autoimmune haemolysis (DAT positive)
Malaria haemolysis / blackwater fever
PNH
Haemotoxic snakebite
Hereditary spherocytosis
When to admit, call ICU or discharge
Admit: Haemoglobinuria, Hb <80–90 g/L, AKI or symptomatic anaemia
ICU: Shock, severe AKI, methaemoglobinaemia with hypoxia
Dialysis: Oliguric AKI with hyperkalaemia, acidosis or overload
Transfuse: Hb <70 g/L, or <90 g/L with active haemoglobinuria
Key points
G6PD deficiency is X-linked and common in India, especially in some tribal and western/north-eastern communities — test before primaquine or dapsone where possible.
Haemolysis is mostly intravascular and self-limiting once the oxidant is gone; the kidney is the organ at risk.
Women can be affected (heterozygotes with skewed X-inactivation) — sex does not exclude it.
Never
Give methylene blue for methaemoglobinaemia in G6PD deficiency — it causes more haemolysis
Give rasburicase without knowing G6PD status
Trust a normal G6PD assay taken during haemolysis
Restart primaquine at the standard daily dose
Common mistakes
Missing the trigger drug on the chart
Testing G6PD during the episode
Methylene blue for methaemoglobinaemia
Under-hydrating a patient with haemoglobinuria
Disposition and follow-up
Ward until urine clears and Hb is stable; nephrology if AKI. Confirmatory G6PD assay at 2–3 months and a written unsafe-drug list.
ICU Decoded — original critical-care and internal-medicine pathways by
Dr Javed Akhtar, each cited to a current guideline. For education and quick
reference; verify every dose against local protocols before prescribing.