The mnemonic
FAT RN
What each word stands for
- FFever
- AAnaemia (microangiopathic haemolytic)
- TThrombocytopenia
- RRenal dysfunction
- NNeurological signs
Why it matters clinically
Prompts urgent plasma exchange when TTP is suspected, caused by ADAMTS13 deficiency.
Where it stops being reliable
The full pentad is present in only a minority of patients, so do not wait for all five.
Teaching aid, still awaiting independent review. Confirm facts in a standard source.