On your nightshift, the bedside nurse asks you to review a 65-year-old female with red urine in her indwelling urinary catheter bag.
When the urine is red and free of haem pigments (e.g. erythroctyes, haemoglobin or myoglobin), then the urine may be discoloured and described as 'raspberry', or 'cherry-red'
Hydroxocobalamin is a vitamin B12 (cyanocobalamin) precursor. In high doses, it is an effective chelator of cyanide. It is also the preferred antidote to cyanide poisoning due to its low side effect profile, thus if given to a patient without cyanide poisoning there is low risk of an adverse outcome
Cyanide is a potentially lethal toxic agent that can be found in liquid and gaseous form. First discovered in 1786 by Scheele, who extracted it from the dye Prussian blue - and promptly died from exposure to the vapours