Rhabdo

Question 1

Rhabdomyolysis is caused by skeletal muscle breakdown.
This causes the release of intracellular contents such

Answer 1

myoglobin and potassium into the blood stream

Excess myoglobin can precipitate in the glomerulus causing renal obstruction, direct nephrotoxicity and acute kidney injury.

Question 2

causes

Answer 2

Trauma: prolonged immobilisation (e.g. long lie in elderly patients), crush injuries, burns, seizures, compartment syndrome.
Ischaemia: embolism, surgery
Toxins: Statins, fibrates, ecstasy, neuroleptics
NB: It can also present following very strenuous exercise (e.g. spin class).

Question 3

symptoms

Answer 3

Muscle pain, swelling
Red/brown urine
Acute kidney injury 10-12 hours after initial pain/injury

Question 4

investigations
what 5 things show this

what gives a false postibve in urine

Answer 4

Creatine kinase - the most reliable indicator of muscle damage. A 5 fold rise from the upper limit of the reference range suggests rhabdomyolysis although the levels are often much higher.
Raised LDH (suggestive of muscle damage)
Hyperkalaemia (liberated from the damaged muscle)
Hyperphosphatemia (liberated from the damaged muscle)
Hyperuricaemia (liberated from damaged muscle)
Hypocalcaemia (calcium is taken into the damaged muscle by several mechanisms).
Urine tests will often be falsely positive for blood on dipstick with no red blood cells seen on microscopy. This is due to the myoglobinuria, which is the reason why the urine is typically described as tea- or cola-coloured urine

Question 5

management

Answer 5

Patients are often treated with supportive therapy. This includes IV fluids and management of hyperkalaemia.