Remember to check a creatinine phosphokinase (CPK) in patients who present with significant"muscle aches"
Author:
Lindsey Albrecht, MD
What to Do - Gather Appropriate Data,
Interpret the Data
Rhabdomyolysis is often misdiagnosed and not worked up in children and
adolescents with systemic viral illnesses, extreme heat, or who have over-
exercised.
Complaintsofmuscleachesarecommoninpediatrics.Inmostinstances,
the aches are transient and benign; occasionally, though, a more significant
underlying problem may exist. Rhabdomyolysis is a potentially serious cause
of myalgia in childhood and is characterized by the breakdown of striated
muscle tissue. Muscle breakdown results in the leakage of muscle cell constituents,includingcreatinekinase(CK)andmyoglobin,intothecirculation.
Myoglobinuriamayresultinacuterenalfailure,themostsevereconsequence
of rhabdomyolysis. Rhabdomyolysis in the pediatric population differs from
rhabdomyolysis in the adult population with respect to etiology, clinical presentation, and prognosis.
In children, rhabdomyolysis is frequently the result of viral myositis,
trauma, connective tissue disease, and drug overdose. In early childhood, viral infection is the leading cause, accounting for almost 40% of all childhood
rhabdomyolysis. Trauma, resulting in muscle compression or muscle injury,
is the leading cause of rhabdomyolysis in children older than 9 years of age.
Trauma accounts for approximately 26% of all pediatric cases of rhabdomyolysis.Vigorousexerciseiswellknowntooccasionallyinducerhabdomyolysis
in children and adults and accounts for approximately 4% of pediatric cases.
In one case report, 119 students developed myalgia and elevation in CK
after being instructed to perform 120 pushups in 5 minutes by their gymnastics teacher. Exercise-induced rhabdomyolysis is especially likely if the
temperature and humidity are high. Metabolic disorders, such as diabetic
ketoacidosis, McArdle disease, and aldolase A deficiency, may additionally
result in rhabdomyolysis in the pediatric patient.
The classic presentation consists of a triad of muscle pain, weakness,
anddarkurine, but occurs infrequently inthe pediatric patient. Inthe largest
pediatric study to date, only 1 out of 191 patients had all three symptoms.
Myalgia was noted in 45% of patients, weakness in 38%, and dark urine in
approximately 4% of children in this study. Common additional presenting features included fever in 40%, muscle tenderness in 39%, and viral
symptoms in 39%.
Laboratory evaluation of rhabdomyolysis should include serum CK,
basic chemistry panel, and urinalysis. Definitive diagnosis of rhabdomyolysis is usually made when serum CK is >5 times normal without evidence
of significant elevation of cardiac or brain fractions (CK-MB or CK-BB).
Urine dipstick analysis may be positive for hemoglobin but have a microscopic examination that does not demonstrate erythrocytes. This represents
myoglobinuria rather than hematuria. Acute renal failure (ARF) is rarely
seen in pediatric patients with urinary heme dipstick results of <2+. ARF is
more frequent with higher heme dipstick results (>2+), but still only occurs
in 5% of all pediatric cases. The serum CK is correlated with the degree
of renal dysfunction, because higher CK values are associated with higher
serum creatinine levels. In addition to the much lower incidence of ARF
versus that in adults, children also tend to not develop chronic renal failure
as frequently.
Treatment of rhabdomyolysis in childhood should include early initiation of fluid therapy. Most clinicians tend to treat with 1.5 to 2 times maintenance fluid needs. The need for bicarbonate administration to alkalinize
the urine, although effective in adults, has not been shown to prevent ARF
in children. Significant electrolyte abnormalities, such as hyperkalemia, are
rare but need to be managed appropriately and aggressively.
Prompt diagnosis of rhabdomyolysis in the pediatric population is often
hampered by a lack of classical symptoms. Patients with myalgia, weakness,
or muscle tenderness should be evaluated for rhabdomyolysis, because serious sequelae such as ARF may occur if early aggressive intravenous fluid
administration is not initiated. Because viral illness and trauma are the leading causes of rhabdomyolysis in childhood, these conditions should raise
suspicion for the diagnosis.
Suggested Readings
Lin AC, Lin CM, Wang TL, et al. Rhabdomyolysis in 119 students after repetitive exercise. Br
J Sports Med. 2005;39(1):e3.
Mannix R, Tan ML, Wright R, et al. Acute pediatric rhabdomyolysis: causes and rates of renal
failure. Pediatrics. 2006;118(5):2119–2125.
Melli G, Chaudhry V, Cornblath DR. Rhabdomyolysis: an evaluation of 475 hospitalized pa
tients. Medicine (Baltimore). 2005;84(6):377–385.
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Book Source Details
- Book Title: Avoiding Common Pediatric Errors
- Author(s): Anthony D Slonim MD, DrPH; Lisa Marcucci MD
- Year of Publication: 2008
- Copyright Details: Avoiding Common Pediatric Errors, Copyright © 2008 Lippincott Williams & Wilkins.
Other Book Chapters Related to Muscle aches
Read excerpts from these other book chapters related to Muscle aches:
Copyright Details: Avoiding Common Pediatric Errors, Copyright © 2008 Williams & Wilkins.
More About Causes of Muscle aches
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More About This Book:
Title: Avoiding Common Pediatric Errors
Authors: Anthony D Slonim MD, DrPH; Lisa Marcucci MD
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7489-6
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» Next page: Medications causing Muscle aches
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