Rhabdomyolysis August 2nd, 2011 - Morning Report
Definition: the rapid breakdown of striated muscle with subsequent release of cellular contents into the extracellular fluid and circulation.
Fun fact:
First description of Rhabdomyolysis is thought to be in the Book of Numbers (Bible or Torah) after the Israelites ate quail and were poisoned. Scholars believe this to be due to cicutoxin from the Hemlock plant that the quail were believed to feed on.
Elevated CK
- CK-MM muscle
- CK-MB heart
- CK-BB brain
DDx for elevated CK-MM (rhabdo)
1. Crush: compartment syndrome; lying on ground immobile
2. Drugs:(statins - risk significantly increases with co-use of fibrates, ecstasy, heroin, cocaine, neuroleptics - NMS), malignant hyperthermia
3. Ischemia: DVT with compartment syndrome, arterial embolus
4. Exertion: seizure, marathoners, muscle builders (think fit vs non-fit)
5. Inflammatory: polymyositis (personal or famil hx of autoimmune disease?), dermatomyositis (look for an underlying tumor)
6. Infection (especially viruses like EBV, coxsackie), Legionnaire's disease
7. Genetic: most common is McArdle's disease (congenital myophosphorylase deficiency), Tarui disease (phosphofructokinase disease), carnitine deficiency
8. Endocrine: hypo > hyperthyroid
First description of Rhabdomyolysis is thought to be in the Book of Numbers (Bible or Torah) after the Israelites ate quail and were poisoned. Scholars believe this to be due to cicutoxin from the Hemlock plant that the quail were believed to feed on.
Elevated CK
- CK-MM muscle
- CK-MB heart
- CK-BB brain
DDx for elevated CK-MM (rhabdo)
1. Crush: compartment syndrome; lying on ground immobile
2. Drugs:(statins - risk significantly increases with co-use of fibrates, ecstasy, heroin, cocaine, neuroleptics - NMS), malignant hyperthermia
3. Ischemia: DVT with compartment syndrome, arterial embolus
4. Exertion: seizure, marathoners, muscle builders (think fit vs non-fit)
5. Inflammatory: polymyositis (personal or famil hx of autoimmune disease?), dermatomyositis (look for an underlying tumor)
6. Infection (especially viruses like EBV, coxsackie), Legionnaire's disease
7. Genetic: most common is McArdle's disease (congenital myophosphorylase deficiency), Tarui disease (phosphofructokinase disease), carnitine deficiency
8. Endocrine: hypo > hyperthyroid
*The schematic above showing the causes and complications of rhabdomyolysis was taken from the article: Cervellin G, Comelli I, Lippi G. Rhabdomyolysis: historical background, clinical, diagnostic and therapeutic features. Clin Chem Lab Med. 2010 Jun;48(6):749-56.
Clinical features:
Clinical features:
- classic triad: muscle pain, brown pigmented urine (myoglobinuria), weakness seen in <10% of patients
- can be asymptomatic with only elevated CK
- myalgias, pain, pigmented urine, fever, malaise, tachycardia, nausea/vomiting
- AKI can be seen if CK>5000
- complications: renal failure, DIC, and death in ~5% of cases
- urine myoglobin is not useful in diagnosis
- CK is the biochemical gold standard
- other investigations: elevated AST>ALT, LDH, UA
Treatment:
- FLUIDS!
- little support for the use of mannitol, Lasix, or bicarb
- manage the electrolyte derangements (hyperkalemia, hypocalcemia)
- severe hyperkalemia may require dialysis - shifting with insulin may not work if extensive tissue damage led to rhabdo
Moderate-intensity exercise (HR 55-90% max) is enough to elevate CK levels to the mid-thousands, particularly if "eccentric muscle contractions" like weight lifting or running downhill. More info can be found in the article:
Moderate-intensity exercise (HR 55-90% max) is enough to elevate CK levels to the mid-thousands, particularly if "eccentric muscle contractions" like weight lifting or running downhill. More info can be found in the article:
Latham J, Campbell D, Nichols W, Mott T. Clinical inquiries. How much can exercise raise creatine kinase level--and does it matter? J Fam Pract. 2008 Aug;57(8):545-7.
