13. Rhabdomyolysis

Question 1

What is rhabdomyolysis

Answer 1

a condition where skeletal muscle tissue breaks down and releases breakdown products into the blood
this is usually triggered by an event that causes the muscle to break down; such as. extreme. underuse or overuse. or a. traumatic injury

Question 2

The muscle cells (myocytes) undergo cell death (apoptosis) and this results in the myocyte releasing which substances

Answer 2

myoglobin
potassium
phosphate
creatine kinase

Question 3

out of the following products that the myocytes releases which the most immediately dangerous breakdown product and why

myoglobin
potassium
phosphate
creatine kinase

Answer 3

potassium as hyperkalaemia can cause cardiac arrhythmias

Question 4

out of the following breakdown products which is the most toxic to the kidney in high concentrations

myoglobin
potassium
phosphate
creatine kinase

Answer 4

myoglobin

Question 5

Name some causes of rhabdomyolysis

Answer 5

Anything that causes significant damage to muscle cells can cause rhabdomyolysis:

• Prolonged immobility, particularly frail patients that fall and spend time on the floor before being found
• Extremely rigorous exercise beyond the person’s fitness level (e.g. ultramaraton, triathalon, crossfit competition)
• Crush injuries
• Seizures

Question 6

what are the signs and symptoms of rhabdomyolysis

Answer 6

• Muscle aches and pain
• Oedema
• Fatigue
• Confusion (particularly in elderly frail patients)
• Red-brown urine

Question 7

what investigations are carried out to diagnose rhabdomyolysis

Answer 7

CK
Myoglobin- cause urin to be red-brown and urine dipstick will be positive for blood
U&E to look at AKI and hyperkalaemia
ECG important to assess heart in response to hyperkalaemia

Question 8

what is the management of rhabdomyolysis

Answer 8

IV fluids are the mainstay of treatment. The aim is to rehydrate the patient and encourage filtration of the breakdown products.

Consider IV sodium bicarbonate. This aims to make the urine more alkaline (pH ≥ 6.5), reducing the toxicity of the myoglobin on the kidneys. The evidence on this is not clear and there is some debate about whether to use it.

Consider IV mannitol. This aims to increase the glomerular filtration rate to help flush the breakdown products and to reduce oedema surrounding muscles and nerves. Hypovolaemia should be corrected before giving mannitol. The evidence on this is not clear and there is some debate about whether to use it.

Treat complications, particularly hyperkalaemia. Hyperkalaemia can be immediately life threatening as it can cause arrhythmias (particularly ventricular fibrillation)