Haemolytic Uraemic Syndrome, Rhabdomyolysis

Question 1

What is Haemolytic Uraemic Syndrome?

Answer 1

Occurs when there is thrombosis in small blood vessels throughout the body

Usually triggered by a bacterial toxin called the shiga toxin

Triad of:
Haemolytic anaemia
Acute kidney injury
Low platelet count (thrombocytopenia)

Question 2

How do the features of HUS occur?

Answer 2

Formation of blood clots consumes platelets, leading to thrombocytopenia

Blood clots within the small vessels chop up the red blood cells as they pass by (haemolysis) - anaemia

Blood flow through the kidney is affected by the clots and damaged red blood cells, leading to acute kidney injury

Question 3

What is the most common cause of HUS?

Answer 3

Toxin produced by the bacteria e. coli 0157 called the shiga toxin

Shigella also produces this toxin and can cause HUS

Question 4

What is the management of HUS?

Answer 4

Medical emergency and has up to 10% mortality

Self limiting and supportive management is the mainstay of treatment:
Antihypertensives
Blood transfusions
Dialysis

70-80% of patients make a full recovery

Use of antibiotics and anti-motility medications such as loperamide to treat the gastroenteritis increase the risk of developing HUS

Question 5

How does HUS present?

Answer 5

E. coli 0157 causes a brief gastroenteritis often with bloody diarrhoea

Symptoms presents 5 days after the diarrhoea

Reduced urine output

Haematuria or dark brown urine

Abdominal pain

Lethargy and irritability

Confusion

Hypertension

Bruising

Question 6

What is Rhabdomyolysis?

Answer 6

Skeletal muscle tissue breaks down and releases breakdown products into the blood

Usually triggered by an event that causes the muscle to break down, such as extreme underuse or overuse or a traumatic injury

Question 7

What do myocytes release during apoptosis?

Answer 7

Myoglobin (causing myoglobinurea)

Potassium

Phosphate

Creatine kinase

Question 8

Dangers of rhabdomyolysis

Answer 8

Hyperkalaemia (cardiac arrest)

Myoglobin in particular is toxic to the kidney in high concentrations - can cause AKI

Question 9

Causes of Rhabdo

Answer 9

Prolonged immobility, particularly frail patients that fall

Extremely rigorous exercise beyond the person’s fitness level (e.g. ultramaraton, triathalon, crossfit competition)

Crush injuries

Seizures

Question 10

Signs of symptoms of rhabdo

Answer 10

Muscle aches and pain

Oedema

Fatigue

Confusion (particularly in elderly frail patients)

Red-brown urine

Question 11

Investigations used when suspecting rhabdo

Answer 11

Creatine Kinase (CK) - thousands to hundreds of thousands of Units/L
Rises until 12 hours, then remains elevated for 1-3 days, then falls gradually
Increases risk of AKI

Myoglobinurea - urine dipstick to be positive for blood

Urea and electrolytes (U&E) blood tests for acute kidney injury and hyperkalaemia

ECG - hypekalaemia

Question 12

What is the management of rhabdomyolysis?

Answer 12

IV fluids - rehydrate the patient and encourage filtration of the breakdown products

Mannitol - aims to increase the glomerular filtration rate and reduce oedema

Treat complications (hyperkalaemia)

Consider IV sodium bicarbonate
Make the urine more alkaline (pH ≥ 6.5) (debated)