Rhabdomyolysis

Clinical Presentation

Patients with rhabdomyolysis typically present following a period of muscle compression or severe exertion. Common scenarios include individuals trapped under heavy objects for extended periods, falls resulting in prolonged immobility on the floor, marathon runners, or those with a history of severe crush injuries. IV drug abusers found immobilized for an extended time and elderly individuals with a history of frequent falls are also at risk. They might report or exhibit signs such as:

1. Haematuria characterized by reddish-brown or tea-coloured urine, which is a false positive since the redness arises from myoglobin presence, not RBCs.

2. Hypotension

3. Potential signs of acute kidney injury (AKI).

Risk Factors

. Extended physical immobilization.

. Severe exertion or dehydration, such as seen in long-distance runners.

. IV drug abuse.

. Elderly individuals prone to frequent falls.

. Certain medications, for instance, one of the rare side effects of statins is rhabdomyolysis.

Investigations

Upon suspecting rhabdomyolysis, several diagnostic tests should be ordered:

i. Urine Analysis: The primary initial test is to look for the characteristic tea-coloured urine, which indicates the presence of myoglobin, a product of muscle breakdown.

ii. Blood Tests: Checking for high levels of creatine kinase (Confirmatory), which would indicate muscle necrosis, and urea and creatinine levels to assess kidney function.

iii. ECG: Given the risk of hyperkalaemia, resultant from potassium release by the damaged muscles, an ECG must be done to detect changes such as tall, tented T waves or a wide QRS complex, which are indicative of high potassium levels in the blood.

Management

Management of rhabdomyolysis aims to prevent major complications such as AKI and hyperkalaemia and revolves around urgent and vigilant care:

1. Initial Intervention: Immediate rehydration with IV fluids, which serves to protect the kidneys from the nephrotoxic effect of myoglobin.

2. Heart Protection: In cases where ECG shows signs of hyperkalaemia, administering IV calcium chloride or calcium gluconate becomes a priority to protect the heart even before IV Fluids.

3. Monitoring and Additional Treatment: Continuous monitoring of the patient’s ECG and potential initiation of other treatments like sodium bicarbonate administration and, in severe cases, dialysis to manage kidney function.

Important Points

. Primary complications to watch out for are AKI and hyperkalaemia.

. First-line treatment involves rehydration with IV fluids to mitigate the risk of AKI.

. Best initial diagnostic test: Urine analysis to check for falsely positive haematuria due to the presence of myoglobin.

. Confirmation of Diagnosis: Elevated Creatine Phosphokinase (CPK) levels would confirm muscle necrosis, indicative of rhabdomyolysis.