Rhabdomyolysis, sometimes called “rhabdomyolysis” in clinical parlance, means “muscle breakdown.” This is a clinical syndrome in which muscles begin to break down and cause changes in fluid and electrolyte levels in the body, which can lead to harmful consequences.
Causes of Rhabdomyolysis
Various factors are associated with rhabdomyolysis. Here are some examples:
- Drugs; eg. Statins and fibrates (drugs used to lower cholesterol), colchicine (a gout drug), psychotropic drugs, antibiotics, steroids, etc.
- Excessive strenuous exercise can lead to a phenomenon called exercise-induced rhabdomyolysis or exertional rhabdomyolysis
- High temperatures that lead to heat stroke are the triggers.
- Illicit drugs such as cocaine and amphetamines, as well as alcohol
Symptoms of Rhabdomyolysis
Often, affected patients report extreme muscle pain, muscle stiffness, swelling, weakness, and sometimes “dark/cola-colored urine.” Dehydration is common, and patients may experience changes in mental status and low blood pressure, leading to dizziness, lightheadedness, decreased urine output, and more. Fever may also occur.
How Rhabdomyolysis Affects the Kidneys
Rhabdomyolysis affects kidney function in several ways. The breakdown of the muscle causes fluid to flow out of the blood vessels into the injured muscle, essentially creating and worsening the dehydration state. This in itself is sometimes enough to cause a severe decline in kidney function, commonly known as acute kidney injury. Electrolyte levels in the blood also change, manifesting as:
- increased phosphorus content
- decreased calcium levels
- Elevated potassium levels
- Elevated uric acid levels
Another way rhabdomyolysis can damage the kidneys is through a phenomenon called myoglobinuria. Myoglobin is a protein found in muscles. When muscles are broken down, this myoglobin is released into the bloodstream, and from there it goes to the kidneys. The kidneys are not good at excreting myoglobin, a protein that, in addition to being toxic to kidney cells, often blocks the kidney’s “drainage system”, the renal tubules. This can lead to kidney failure. In the worst case, renal failure due to myoglobinuria-induced rhabdomyolysis can lead to irreversible renal failure requiring long-term dialysis.
The diagnosis of rhabdomyolysis depends on the clinical presentation, including symptoms and signs such as muscle pain. Some more specific symptoms include cola-colored urine. Laboratory tests are done to support the diagnosis and usually show significantly elevated blood levels of a chemical called creatinine phosphokinase (CPK). Kidney failure may also be evident on blood tests, with elevated creatinine levels. A urine test may show the presence of myoglobin, an abnormal protein released into the urine after muscle is broken down.
In addition to treating the main cause of it, the key to rhabdomyolysis treatment is correcting abnormal electrolyte levels and aggressive hydration of affected patients with intravenous fluids. There is some debate about which IV fluid is best for the patient in this situation. Alkalizing urine with sodium bicarbonate and mannitol has been the standard of care for many years. However, its superiority over other intravenous fluids such as saline has never been convincingly demonstrated.
Your doctor will analyze your kidney function when you receive IV fluids. Usually, your symptoms and kidney function should begin to return within a few days, and the urine should begin to clear. However, in some patients, the kidneys may be so damaged that dialysis may be required. Remember, dialysis is a supportive treatment. It does not treat kidney failure by itself; it only replaces kidney function. If the kidneys are going to recover, they will recover on their own, and all patients and doctors can do is give them a supportive environment. In rare cases, patients may be dependent on dialysis for life.