Haemolytic Uraemic Syndrome and Thrombotic Thrombocytopaenic Purpura Flashcards
Define Haemolytic Uraemic Syndrome (HUS) and Thrombotic Thrombocytopaenic Purpura (TTP)?
A triad of:
- Microangiopathic Haemolytic Anaemia (MAHA)
- Acute Renal Failure
- Thrombocytopaenia
What are the two forms of HUS?
D+ = Diarrhoea-associated form D- = No prodromal illness identified
What are the additional features when HUS overlaps with TTP?
Fever
Fluctuating CNS signs
What is the aetiology of HUS and TTP?
Endothelial injury results in platelet aggregation and the release of unusually large vWF multimers and activation of platelets and the clotting casade
This leads to small vessel thrombosis
The glomerular-afferent arteriole and capillaries are particularly vulnerable - they undergo fibrinoid necrosis
This leads to renal ischaemia and acute renal failure
The thrombi also promote intravascular haemolysis
What are the infective causes of HUS and TTP?
Escherichia coli (O157)
Shigella
Neuraminidase-producing infections
HIV
What drugs cause HUS and TTP?
COCP
Ciclosporin
Mitomicin
5-fluorouracil
What are the other causes of HUS and TTP?
Malignant Hypertension Malignancy Pregnancy SLE Scleroderma
What is the epidemiology of HUS and TTP?
Uncommon
D+ HUS often affects YOUNG CHILDREN
It is the most common cause of acute renal failure in children
TTP mainly affects ADULT FEMALES
What are the GI presenting symptoms of HUS and TTP?
Severe abdominal colic
Watery diarrhoea that becomes bloodstained
What are the general symptoms of HUS and TTP?
Malaise
Fatigue
Nausea
Fever < 38 degrees (D+)
What are the renal symptoms of HUS and TTP?
Oliguria or anuria
Haematuria
What are the General signs of HUS and TTP on physical examination?
Pallor Slight Jaundice (due to haemolysis) Bruising Generalise oedema Hypertension Retinopathy
What is the GI sign of HUS and TTP?
Abdominal Tenderness
What are the CNS signs of TTP?
Weakness
Reduced Vision
Fits
Reduced consiousness
What investigations do you do for HUS and TTP?
FBC U&Es Clotting LFTs Blood cultures ABG Blood film Urine Stool samples Renal biopsy
What do we look for specifically on a FBC for HUS and TTP?
Normocytic anaemia
High neutrophils
Very low platelets
What do we look for on U&Es for HUS and TTP?
High Urea
High Creatinine
High K+
Low Na+
What do we look for on a Clotting Screen for HUS and TTP?
Normal APTT and fibrinogen levels (abnormality may indicate DIC)
What do we look for on LFTs for HUS and TTP?
High unconjugated bilirubin
High LDH from haemolysis
What do we look for on an ABG for HUS and TTP?
Low pH
Low bicarbonate
Low PaCO2
Normal anion gap
What do we see on a Blood Film for HUS and TTP?
Schistocytes
High reticulocytes and spherocytes
What do we see on an Urinalysis for HUS and TTP?
1 + g protein/24 hrs
Haematuria
How do we use Stool Samples for HUS and TTP?
MC&S
Why do we do a Renal Biopsy for HUS and TTP?
Can distinguish between D+ and D- HUS
