Move over ‘black hairy tongue’, this case of bright yellow tongue has a far more colourful — and serious — underlying cause, making it ‘hairy’ in an entirely different sense.

A 12-year-old boy presented to hospital after experiencing sore throat, dark urine, abdominal pain and pallor for several days, as well as the unusual tint to his tongue.

On examination, doctors found he had jaundice, noting scleral and tongue icterus.

But the rare reason behind this jaundice was revealed through lab tests: his haemoglobin level was 6.1g/dL (normal range, 11.0-14.5); lactate dehydrogenase level was 6405U/L (normal range, 470-750), unconjugated bilirubin level was 6.7mg/dL (normal value: less than 0.7mg/dL); a direct antiglobulin test was positive, with cold agglutinins detected; and a urinalysis was positive for haemoglobin.