Thrombotic thrombocytopenic purpura Flashcards
Define
Haemolytic uremic syndrome overlaps with thrombotic thrombocytopenic purpura (TTP) which has the additional features of fever and fluctuating CNS signs.
→Many physicians consider them a spectrum of disease
All patients have MAHA (severe, often with jaundice) and low platelets
Other TTP features can include:
- AKI
- Fluctuating CNS signs (e.g. seizures, hemiparesis, ↓consciousness, ↓vision)
- Fever
Cause
genetic or acquired deficiency of a protease
(ADAMTS13) that normally cleaves multimers of VWF
Hence large VWF multimers form, causing platelet aggregation and fibrin deposition in small vessels
Leading to microthrombi
Idiopathic (40%)
- Autoimmunity (e.g. SLE)
- Cancer
- Pregnancy
- Drug associated (e.g. quinine)
- Bloody diarrhoea prodrome
- Haematopoietic stem cell transplant
Risk factors
Epidemiology
mainly affects adult females Mortality can be >90% if untreated (higher than HUS)
Haematological emergency – get expert help
Symtpoms
GI: Severe abdominal colic, watery diarrhoea that becomes bloodstained
General: Malaise, fatigue, nausea, fever <38
Renal: Oliguria or anuria, haematuria
Signs
Classically – CNS signs (weakness, ↓vision, fits, ↓consciousness)
Also:
- General → Pallor (from anaemia), slight jaundice (from haemolysis), bruising (severe thrombocytopaenia), generalized oedema, hypertension and retinopathy
- GI → Abdominal tenderness
Investigations
FBC
- Normocytic anaemia
- High neutrophils
- Very low platelets
U&Es
- High urea
- High creatinine
- High K+
- Low Na+
Clotting
- Normal APTT and fibrinogen levels (abnormality may indicate DIC)
LFTs
- High unconjugated bilirubin
- High LDH from haemolysis
- Blood cultures
ABG
- Low pH
- Low bicarbonate
- Low PaCO2
- Normal anion gap
Blood Film
- Schistocytes
- High reticulocytes and spherocytes
Urine
- 1+ g protein/24 hrs
- Haematuria
Stool Samples
- MC&S
Renal Biopsy
- Can distinguish between D+ and D- HUS
