Can the elevation of AST and ALT in my patient with rhabdomyolysis be related to the muscle injury itself?

Yes! Elevated serum AST and ALT in the setting of rhabdomyolysis is not uncommon and, at least in some cases, appears to be related to the skeletal muscle injury itself.1,2

In a study of 16 patients considered to have significant muscle necrosis due to extreme exercise, polymyositis or seizures without evidence of liver disease (eg, viral hepatitis, exposure to hepatotoxic drugs, heart failure, biliary tract disease, recent hypotension) AST and, to lesser degree, ALT was elevated. For extreme exercise, the median AST and ALT concentrations were 2,466 IU/L and 497 U/L, respectively, while for seizures these levels were 1,448 U/L and 383 U/L respectively.1  

Another study reported AST elevation (>40 U/L) in 93.1% of patients with rhabdomyolysis and ALT elevation (>40 U/L) in 75.0% of patients with serum creatine kinase ≥1000 U/L. Further supporting a skeletal muscle origin for AST elevation was the finding that AST concentrations fell in parallel with CK drop during the first 6 days of hospitalization for rhabdomyolysis. It was posited that ALT concentrations dropped slower because of its longer serum half-life (47 hours vs 17 hours for AST).2 Despite these findings, concurrent liver injury as an additional source of AST or ALT elevation cannot be excluded.

Elevation of AST and ALT with muscle injury should not come as a surprise. AST is found in heart and skeletal muscle among many other organs. Even ALT which is considered more specific to liver is found in organs such as skeletal muscle, heart and kidney, though at lower concentrations.3

Bonus Pearl: Did you know that the first description of rhabdomyolysis in the literature involved English victims of crush injuries during World War II?2

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References

  1. Nathwani RA, Pais S, Reynolds TB, et al. Serum alanine aminotransferase in skeletal muscle diseases. Hepatology 2005;41:380-82. https://www.ncbi.nlm.nih.gov/pubmed/15660433
  2. Weibrecht K, Dayno M, Darling C, et al. Liver aminotransferases are elevated with rhabdomyolysis in the absence of significant liver injury. J Med Toxicol 2010;6:294-300. https://link.springer.com/article/10.1007%2Fs13181-010-0075-9
  3. Giannini EG, Testa R, Savarino V. Liver enzyme alteration: a guidance for clinicians. CMAJ2005;172:367-79. Giannini EG, Testa R, Savarino V. Liver enzyme alteration: a guidance for clinicians. CMAJ 2005;172:367-79. https://www.ncbi.nlm.nih.gov/pubmed/15684121
Can the elevation of AST and ALT in my patient with rhabdomyolysis be related to the muscle injury itself?

How can I distinguish serotonin syndrome from neuroleptic malignant syndrome in my patient with fever and mental status changes?

Although there is often an overlap between the clinical presentation of serotonin syndrome (SS) and neuromuscular malignant syndrome (NMS), start out with the physical exam. The presence of hyperreflexia, tremors, clonus, hyperactive bowel sounds, and dilated pupils should make you think of SS, whereas hyporeflexia, “lead-pipe” rigidity in all muscle groups, normal pupils, and normal or decreased bowels sounds suggest NMS in the proper context.1-3 The most sensitive and specific sign of SS is clonus.1

Aside from physical exam findings, symptom onset in relation to the implicated drug may also be important. Onset of symptoms within 12-24 h of the initiation or change of an implicated drug suggests SS, whereas a more delayed onset (often 1-3 days) is more supportive of NMS.1-3  SS also tends to resolve within a few days after discontinuation of the offending agent, while NMS usually takes 9-14 days to resolve. 1-3 Although both SS and NMS can be associated with leukocytosis, elevated CK and low serum iron levels are more common in NMS.2

SS is caused by excess serotonin due to a variety of mechanisms—therefore medications— including inhibition of serotonin uptake ( eg, serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, tricyclic antidepressants, metoclopramide, ondansetron), inhibition of serotonin metabolism (seen with monoamine oxidase inhibitors , including linezolid, methylene blue), increased serotonin release (eg stimulants, including amphetamines, cocaine), and activation of serotonin receptors (eg, lithium), among others. 2

As for medications that can cause NMS, look for neuroleptic agents (eg, haloperidol, olanzapine, quetiapine, risperidone), as well as antiemeics, such as metoclopramide and promethazine.2

 

Bonus Pearl: Did you know that several supplements/herbal products have been associated with serotonin syndrome, including L-tryptophan, St. John’s wort and ginseng?1

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References

  1. Bienvenu OJ, Neufeld K, Needham DM. Treatment of four psychiatric emergencies in the intensive care unit. Crit Care Med 2012;40: 2662-70. https://insights.ovid.com/crossref?an=00003246-201209000-00017
  2. Turner AAH, Kim JJ, McCarron RM, et al. Differentiating serotonin syndrome and neuroleptic malignant syndrome. Current Psychiatry 2019;18: 36. https://www.mdedge.com/psychiatry/article/193418/schizophrenia-other-psychotic-disorders/differentiating-serotonin-syndrome
  3. Dosi R, Ambaliya A, Joshi H, et al. Serotonin syndrome versus neuroleptic malignant syndrome: a challenging clinical quandary. BMJ Case Rep 2014. Doi:10.1136/bcr-2014-204154. https://casereports.bmj.com/content/2014/bcr-2014-204154

 

How can I distinguish serotonin syndrome from neuroleptic malignant syndrome in my patient with fever and mental status changes?

My patient with sepsis and bacteremia has an extremely high serum Creatine kinase (CK) level. Can his infection be causing rhabdomyolysis?

 Absolutely! Although trauma, toxins, exertion, and medications are often listed as common causes of rhabdomyolysis, infectious etiologies should not be overlooked as they may account for 5% to 30% or more of rhabdomyolysis cases (1,2).

Rhabdomyolysis tends to be associated with a variety of infections, often severe, involving the respiratory tract, as well as urinary tract, heart and meninges, and may be caused by a long list of pathogens (1).  Among bacterial causes, Legionella sp. (“classic” pathogen associated with rhabdomyolysis), Streptococcus sp. (including S. pneumoniae), Salmonella sp, Staphylococcus aureus, Francisella tularensis have been cited frequently (3).  Some series have reported a preponderance of aerobic gram-negatives such as Klebsiella sp., Pseudomonas sp. and E. coli  (1,2).   Among viral etiologies, influenza virus, human immunodeficiency virus, and coxsackievirus are commonly cited (2,3).  Fungal and protozoal infections (eg, malaria) may also be associated with rhabdomyolysis (5).

So how might sepsis cause rhabdomyolysis? Several potential mechanisms have been implicated, including tissue hypoxemia due to sepsis, direct muscle invasion by pathogens (eg, S. aureus, streptococci, Salmonella sp.), toxin generation (eg, Legionella), cytokine-mediated muscle cell toxicity (eg, aerobic gram-negatives) as well as muscle ischemia due to shock (1,5).

Bonus Pearl: Did you know that among patients with HIV infection, infections are the most common cause (39%) of rhabdomyolysis (6)? 

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References

1. Kumar AA, Bhaskar E, Shantha GPS, et al. Rhabdomyolysis in community acquired bacterial sepsis—A retrospective cohort study. PLoS ONE 2009;e7182. Doi:10.1371/journa.pone.0007182. https://www.ncbi.nlm.nih.gov/pubmed/19787056.

2. Blanco JR, Zabaza M, Sacedo J, et al. Rhabdomyolysis of infectious and noninfectious causes. South Med J 2002;95:542-44. https://www.ncbi.nlm.nih.gov/pubmed/12005014

3. Singh U, Scheld WM. Infectious etiologies of rhabdomyolysis:three case reports and review. Clin Infect Dis 1996;22:642-9. https://www.ncbi.nlm.nih.gov/pubmed/8729203

4. Shih CC, Hii HP, Tsao CM, et al. Therapeutic effects of procainamide on endotoxin-induced rhabdomyolysis in rats. PLOS ONE 2016. Doi:10.1371/journal.pone.0150319. https://www.ncbi.nlm.nih.gov/pubmed/26918767

5. Khan FY. Rhabdomyolysis: a review of the literature. NJM 2009;67:272-83. http://www.njmonline.nl/getpdf.php?id=842

6. Koubar SH, Estrella MM, Warrier R, et al. Rhabdomyolysis in an HIV cohort: epidemiology, causes and outcomes. BMC Nephrology 2017;18:242. DOI 10.1186/s12882-017-0656-9. https://bmcnephrol.biomedcentral.com/track/pdf/10.1186/s12882-017-0656-9

My patient with sepsis and bacteremia has an extremely high serum Creatine kinase (CK) level. Can his infection be causing rhabdomyolysis?

What is the utility of urine dipstick for blood in diagnosing rhabdomyolysis?

Although the dipstick method of detecting blood in the urine is convenient, it cannot differentiate between hemoglobin, myoglobin, or red blood cells. 1

Several reviews suggest that urine myoglobin is unstable with subpar performance in rhabdomyolysis1, often defined as creatine kinase (CK) elevation 5 times the upper limit of normal in the proper context (eg, crush injury, hypoxic/ischemic or drug injury). A sensitivity of 71% and a specificity of 54% for urine hemoglobin by dipstick, and a sensitivity of 25% and specificity of 75%  for urine myoglobin  has been reported in patients with serum CK >10,000 U/L. 3  

So while a positive dipstick for blood with few or no RBCs in the urine may make us think about rhabdomyolysis, its absence should not be used to exclude it in a susceptible host.

Bonus Pearl: Did you know that consumption of quail has been associated with rhabdomyolysis, possibly due to their feeding on poisonous plants such as hemlock?

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References

  1. Rodriguez-Capote Karina, Balion CM, Hill SA, et al. Utility of urine myoglobin for the prediction of acute renal failure in patients with suspected rhabdomyolysis: A systematic review. Clin Chem 2009;55:2190-97. https://www.ncbi.nlm.nih.gov/pubmed/19797717
  2. Nance JR, Mammen AL. Diagnostic evaluation of rhabdomyolysis. Muscle Nerve 2015;51:793-810. https://www.ncbi.nlm.nih.gov/pubmed/25678154
  3. Grover DS, Atta MG, Eustace JA, et al. Lack of clinical utility of urine myoglobin detection by microconcentrator ultrafiltration in the diagnosis of rhabdomyolysis. Nephrol Dial Transplant 2004;19:2634-38. https://www.ncbi.nlm.nih.gov/pubmed/15280520
What is the utility of urine dipstick for blood in diagnosing rhabdomyolysis?