Exertional rhabdomyolysis: early recognition is key

Twelve cases of exertional rhabdomyolysis in college football players from the same institution over a 23-year span: a descriptive study

BACKGROUND

Rhabdomyolysis is a syndrome characterized by muscle necrosis that leads to release of the intracellular contents of muscle cells into the systemic circulation. Rhabdomyolysis due to overexertion is an uncommon but well-known severe complication of strenuous activity. Exertional rhabdomyolysis (ER) is typically described in weight lifters and military recruits undergoing basic training. Few cases have been reported in football players without known predisposing risk factors. We report our experience with this condition in college football players in a single institution.

MATERIALS AND METHODS

College football players hospitalized for heat illness complicated by rhabdomyolysis were identified over a 23-year period. Clinical and laboratory findings were collected. Clinical course was recorded.

RESULTS

Twelve patients were identified. All were Black males. One had sickle cell trait. BMI averaged 33 kg/m² (range 23-45 kg/m²). Peak creatine phosphokinase (CPK) averaged 14,850 IU/L (range 1,021-109,616 IU/L). Serum creatinine averaged 1.9 mg/dl (range 1.2-3.1 mg/dl). Ten of twelve cases occurred in August. All responded to intravenous hydration with normalization of CPK and renal function. All returned to football.

CONCLUSIONS

ER is a serious complication of strenuous physical activity that can threaten renal function. ER tends to occur in August, which coincides with the start of football practice when athletes are more likely to be detrained. The condition can occur in Black athletes in the absence of sickle cell trait. ER carries a good prognosis when recognized early and treated adequately.

Optimal composition of fluid-replacement beverages

The objective of this article is to provide a review of the fundamental aspects of body fluid balance and the physiological consequences of water imbalances, as well as discuss considerations for the optimal composition of a fluid replacement beverage across a broad range of applications. Early pioneering research involving fluid replacement in persons suffering from diarrheal disease and in military, occupational, and athlete populations incurring exercise- and/or heat-induced sweat losses has provided much of the insight regarding basic principles on beverage palatability, voluntary fluid intake, fluid absorption, and fluid retention. We review this work and also discuss more recent advances in the understanding of fluid replacement as it applies to various populations (military, athletes, occupational, men, women, children, and older adults) and situations (pathophysiological factors, spaceflight, bed rest, long plane flights, heat stress, altitude/cold exposure, and recreational exercise). We discuss how beverage carbohydrate and electrolytes impact fluid replacement. We also discuss nutrients and compounds that are often included in fluid-replacement beverages to augment physiological functions unrelated to hydration, such as the provision of energy. The optimal composition of a fluid-replacement beverage depends upon the source of the fluid loss, whether from sweat, urine, respiration, or diarrhea/vomiting. It is also apparent that the optimal fluid-replacement beverage is one that is customized according to specific physiological needs, environmental conditions, desired benefits, and individual characteristics and taste preferences.

Sickle cell trait testing and athletic participation: a solution in search of a problem?

Carriers of a single sickle cell gene mutation generally enjoy normal lifespans without serious health consequences related to their sickle cell status, but under extreme conditions such as severe dehydration and high-intensity physical activity, complications such as exertional rhabdomyolysis, splenic infarction, and papillary necrosis can occur. Recently, the National Collegiate Athletic Association (NCAA) adopted a policy that requires sickle cell solubility testing for all incoming student athletes. However, the American Society of Hematology (ASH) and other physician organizations oppose this policy. What is the basis for this controversy and how have new findings moved the field forward? I discuss herein the epidemiology, genetics, and clinical studies of sickle cell trait; review the implications of current policies regarding sickle cell trait screening and interventions for the student athlete; and examine additional areas where more information is needed.

Rhabdomyolysis caused by a potential sitagliptin-lovastatin interaction

A 75-year-old woman with diabetes mellitus, hypertension, and hyperlipidemia came to the emergency department with generalized and upper-extremity weakness; she had experienced a fall 2 months earlier. On admission, her drug therapy included lovastatin 40 mg/day, controlled-release diltiazem 240 mg/day, and glimepiride 1 mg/day. Nineteen days earlier, sitagliptin 100 mg/day had been started; it was discontinued 2 weeks later, and glimepiride was begun. A cardiology consultation performed on the day of admission determined that a markedly elevated creatine kinase-myocardial band isoenzyme level and borderline-high troponin I level were diagnostic of rhabdomyolysis secondary to statin use. Because the patient had been taking lovastatin for the past 12 years, the possibility that the rhabdomyolysis may have been caused by a drug interaction between lovastatin and a concomitant drug was evaluated. As it had been 10 months since her last dosage adjustment of diltiazem, it was unlikely that the statin-induced rhabdomyolysis was precipitated by diltiazem. Use of the Drug Interaction Probability Scale to determine the strength of a lovastatin-sitagliptin interaction indicated a possible association (score of 4). Multiple drug interactions have been reported with lovastatin. To our knowledge, however, this is the first case report of a possible sitagliptin-lovastatin interaction that may have caused rhabdomyolysis. Studies must be performed to further evaluate the in vivo effect of sitagliptin on the cytochrome P450 3A4 enzyme system and to elucidate other mechanisms that may potentiate such a drug-drug interaction. In the meantime, however, clinicians should be aware of this possible drug interaction.

Exertional rhabdomyolysis and acute kidney injury

Skeletal muscle breakdown occurs normally with exercise, followed by muscle repair and physiologic adaptation. Strenuous, unaccustomed, prolonged, and repetitive exercise, particularly when associated with other risk factors such as hot and humid climate or sickle cell trait can cause clinically significant exertional rhabdomyolysis (ER). Although most cases are asymptomatic and resolve without sequelae, ER is the most common cause of exercise-related myoglobinuric acute renal injury and acute renal failure in athletes. Exercise-related muscle pain, elevated serum creatine kinase (CK), and "cola-colored" urine have been described as a classic presentation of ER. The exact mechanism of ER has not been clearly elucidated. Most studies suggest a cascade of events that include depletion of adenosine triphosphate (ATP), impaired function of the Na+- K+ ATPase system, intracellular excess calcium accumulation, sarcolemma damage, and release of intracellular proteins and other substances into blood. Excess myoglobin that is filtered at the glomerulus can lead to myoglobinuric acute renal injury. Cessation of physical activity, relative rest during clinical recovery, and early aggressive fluid replacement are mainstays of treatment. Return to play after recovery from ER is influenced by associated risk factors that may predispose the athlete to recurrence and is guided by signs, symptoms, and CK levels. This article reviews the definitions, pathophysiology, diagnosis, and management of ER with specific relevance to acute kidney injury.

Exercise and Fluid Replacement

This Position Stand provides guidance on fluid replacement to sustain appropriate hydration of individuals performing physical activity. The goal of prehydrating is to start the activity euhydrated and with normal plasma electrolyte levels. Prehydrating with beverages, in addition to normal meals and fluid intake, should be initiated when needed at least several hours before the activity to enable fluid absorption and allow urine output to return to normal levels. The goal of drinking during exercise is to prevent excessive (>2% body weight loss from water deficit) dehydration and excessive changes in electrolyte balance to avert compromised performance. Because there is considerable variability in sweating rates and sweat electrolyte content between individuals, customized fluid replacement programs are recommended. Individual sweat rates can be estimated by measuring body weight before and after exercise. During exercise, consuming beverages containing electrolytes and carbohydrates can provide benefits over water alone under certain circumstances. After exercise, the goal is to replace any fluid electrolyte deficit. The speed with which rehydration is needed and the magnitude of fluid electrolyte deficits will determine if an aggressive replacement program is merited.

Rhabdomyolysis

Rhabdomyolysis is the dissolution of skeletal muscle. Breakdown of the myocyte causes the extravasation of intracellular constituents, leading to a clinical syndrome--the classic triad of brown urine, muscle pain, and weakness. The pathogenesis of rhabdomyolysis is presented.