A 29 year old man presents with 2 days of dark urine, fevers and yellow eyes. He has mild RUQ tenderness. His oxygen sats are 80% RA with a normal BP and PR

Arterial gas/bloods on RA:pCO2  32

pO2  90 mmHg

HCO3  23  (22-26  mmol/l)

Hb  91

COHb  4.5

MetHb  7.0

Na  138  (137-145  mmol/l)

K  4 (3.5-5  mmol/l)

Cl  106  (99-111  mmol/l)

Hct  0.29

MCV  90  (80-100)

MCHC  341  (320-360)

MCH  31

Platelets  232  (140-400)

WCC  15.1  (4-11)

Bilirubin  104  (<21  umol/l)

Urea  8.4  (3-8  mmol/l)

The blood smear shows poikilocytosis and sperocytosis with some fragmented red cells.

Describe and Interpret the blood results

What single question may lead to a diagnosis?

Thanks to Carly for this one and excellent spot diagnosis