Case of the Month 7 – Answer

This patient clearly has rhabdomyolysis, and fluid resuscitation will be crucial to protect his renal function. Furthermore, he will clearly require admission to the hospital for further care. So all in all, this case could be a quick open-close for us in the ED once the labs come back, and the diagnosis is made. But what exactly caused this patient to develop rhabdomyolysis? Is there any further workup we can initiate in the ED to help diagnose and treat an underlying pathology? To answer this, we need to understand the different causes of rhabdomyolysis.

Rhabdomyolysis can be divided into four broad categories:

• Traumatic
• Nontraumatic
• Exertional
• Other

This patient falls into that nebulous “other” category and requires further investigation into an inciting event. Let’s further subdivide this category:

Alcohol and other drugs and toxins, infections, electrolyte abnormalities, endocrinopathies, inflammatory myopathies (rare), and other miscellaneous pathologies (baclofen withdrawal, status asthmaticus, depolarizing agents, capillary leak syndrome).

Drugs – Direct muscle damage are related to statins and colchicine. Other mechanisms may be through associated coma and muscle compression, increased metabolic state, or muscle spasms/seizures.

Toxins – Carbon monoxide, snake and arthropod venoms, mushrooms, Haff disease (fish toxin).

Infections –

Viruses:  influenza A and B, Coxsackievirus, Epstein-Barr, herpes simplex, parainfluenza, adenovirus, echovirus, human immunodeficiency virus, and cytomegalovirus.

Bacteria: Legionella, tularemia, Streptococcus, Salmonella, E. coli, leptospirosis, Coxiella burnetii (Q fever), staphylococcal infection, mycoplasma, toxic shock syndrome, erlichiosis, falciparum malaria.

Electrolytes – Hypokalemia, hypophosphatemia

Endocrine – Diabetes, hypo/hyperthyroidism, pheochromocytoma

This list highlights some of the pathologies we need to consider. Some of these cause direct muscle damage; others indirectly through rigors, muscle spasms, or seizures. This patient denies drugs both recreational and pharmaceutical, denies herbs or mushrooms, has normal electrolytes, and no history of immobility or seizures. This should lead us to consider infection and endocrine disorders.

Workup in the ED could likely include thyroid studies, hemoglobin A1c, urinalysis, and urine culture. He could however have a viral cause, although he does not display typically associated viral symptoms. 

This case was written with the idea that this patient has HIV-induced rhabdomyolysis, an uncommon cause of nontraumatic, nonexertional rhabdomyolysis.

Patients may develop rhabdomyolysis at all stages of HIV infection and can be classified into three groups:

1) Primary HIV infection with associated rhabodmyolysis (within 2-8 weeks of primary infection)

2) Rhabdomyolysis associated with HIV medications

3) Rhabdomyolysis associated with AIDS and opportunistic infections

Our patient is not currently taking medications and is not showing stigmata of AIDS. If his rapid HIV test returns positive, he is more likely to have Primary HIV infection with rhabdomyolysis.

Primary HIV infection is increasingly recognized as a clinical syndrome with a wide variety of presentations. Primary infection is frequently a symptomatic process, however it can be subclinical leading to misdiagnosis. Symptoms can resemble a mild flu-like illness: fever, fatigue, sore throat, anorexia, headaches, myalgias, nausea, cervical adenopathy, diarrhea, or rash. Laboratory data can reveal thrombocytopenia, lymphopenia, and elevated hepatic transaminase levels. But truly, the only way to know is to maintain suspicion and send an HIV test.

There isn’t a great understanding how primary HIV infection can cause rhabdomyolysis, but treatment in the ED is the same: fluid resuscitation. Isotonic fluids should be given at a rate of 400mL/hr and then titrated to maintain a urine output of 200mL/hr. Watch for hyperkalemia and treat accordingly. No specific therapy for HIV needs to be initiated during the inpatient stay. Once the patient is stabilized, he can follow up as an outpatient for HIV serotyping and initiation of HAART if he so chooses.

So in summary, “rhabdo is rhabdo is rhabdo” when it comes to ED management in most cases. But through attempt to identify a cause of rhabdomyolysis, we may be able to send a few tests early on that may not alter ED management but will help the inpatient team better manage the patient and provide appropriate follow-up.

References:

Rastegar DA, Claiborne CV, Fleisher AS, Matsumoto AK. A patient with primary human immunodeficiency virus infection who presented with acute rhabdomyolysis Clin Infect Dis 2001;32(3):502-4

Prabahar MR, Jain M, Chandrasekaran V, Indhumathi E, Soundararajan P. Primary HIV Infection Presenting as Non-traumatic Rhabdomyolysis with Acute Renal Failure. Saudi J Kidney Dis Transpl 2008;19:636-42

Del Rio C, Soffer O, Widell JL, Judd RL, Slade BA. Acute human immunodeficiency virus infection temporally associated with rhabdomyolysis, acute renal failure, and nephrosis. Rev Infect Dis 1990;12(2):282-5

http://emedicine.medscape.com/article/1007814-overview. Rhabdomyolysis