Rhabdomyolysis - A Quick ReviewRecalling What You Learned in Cell Biology
Rhabdomyolysis refers to the disintegration of striated muscle with the release of muscle cell contents into the circulation. It is a potentially fatal acute illness requiring aggressive treatment. Common causes of rhabdomyolysis include trauma, prolonged external compression, extreme exertion, and various drugs including, alcohol, cocaine, and opiates. Clinical features of rhabdomyolysis include muscle pain and tenderness, tea-colored urine and, often, chills and fever.
Rhabdomyolysis is a good example of the importance of applying what we learned in Cell Biology to the day-to-day practice of medicine.
By recalling the products of cell breakdown, we remind ourselves of the effects of these products, helping us to predict the results of common laboratory tests, for example, elevations in:
- Urea - the main product of purine metabolism
- Phosphorus - an end product of ATP breakdown
- Potassium, creatine kinase and lactic dehydrogenase - released from dying cells
- Myoglobin - released from dead and dying striated muscle; identified in the urine through the combination of a positive dipstick and absence of red blood cells.
By contrast, hypocalcemia is often noted, the result of blood calcium rushing into dead and dying muscle cells.
Understanding these changes also reinforces the importance of early recognition and treatment of this potentially fatal condition.
Very high levels of creatine kinase (CK) are characteristic of rhabdomyolysis. Blood levels are usually very high by the time the patient is seen and continue to rise for a few days after the precipitating event. Indeed, CK levels at least 5 times the upper limit of normal are commonly cited as a requirement for the diagnosis.
Interestingly, African-Americans and young male athletes tend to have high-normal levels of CK, and samples from normal women tend to be low-normal.
The finding of a positive urine dipstick but no red blood cells on examination of the urine sediment is a common finding.
The only other illness that would explain such a finding is acute intravascular hemolysis leading to hemoglobinuria.
The majority of patients with acute rhabdomyolysis have renal tubular damage from myoglobinuria.
Vigorous hydration and alkalinization of the urine are essential to minimize the effects of myoglobin on the renal tubule.
Rhabdomyolysis knowledge and related acute renal disorders are usually assessed in traditional medical board examinations, especially in emergency medicine. Top-quality board review for rhabdomyolysis and more can be found here.
Figure 1. Rhabdomyolysis
Figure 1. Rhabdomyolysis Algorithm
O’Connor FG, Duester PA. Rhabdomyolysis. Goldman-Cecil Medicine, 2020; 105: 694-698.e2
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