160 SECTION 3 • MEDICAL PROBLEMS IN THE ATHLETE
such as maximal short-term effort, rather than pro-
longed activity.- Important historical questions include exposure to
nephrotoxic drugs, IV drug use, and chronic condi-
tions, such as diabetes, systemic lupus erythematosus,
or chronic active hepatitis. A family history of heredi-
tary nephritis or polycystic kidney disease is important. - Often, the proteinuria is an incidental finding and the
patient should be questioned about prior exercise, its
duration and, more importantly, its intensity.
•A meticulous physical examination should be com-
pleted. Vital signs, especially blood pressure, should
always be obtained. The back, flank, abdomen, skin,
and genitalia are examined in routine fashion. The
extremities are evaluated for any signs of edema.
DIFFERENTIAL DIAGNOSIS AND TREATMENT
- Differential diagnosis includes exercise-induced pro-
teinuria, orthostatic proteinuria, glomerulonephritis,
nephrotic syndrome, and multiple myeloma. - Proteinuria is usually identified through dipstick test-
ing and, when exercise-induced, is usually 2+to 3+.
•False positives occur because of very concentrated
urine, gross hematuria, alkaline urine, or phenazopy-
ridine.- See “proteinuria algorithm” (Figure 27-2) for evalua-
tion and treatment.
ACUTE RENAL FAILURECLINICAL FEATURES- Acute renal failure in athletes is typically caused by
complications associated with strenuous exercise such
as rhabdomyolysis, dehydration, or hyperpyrexia.
Increased magnitude and duration of dehydration can
lead to acute tubular necrosis. Hemolysis due to
hyperpyrexia contributes to acute tubular necrosis
(ATN) and renal failure. - Nonsteroidal anti-inflammatory agents inhibit prost-
aglandins thereby decreasing renal blood flow and con-
tribute to acute renal failure in athletes who premedicate
in the hopes of decreasing postexercise muscle soreness.
Experienced athletes are at much lower risk to develop
acute renal failure than untrained athletes.
FIG. 27-2 Proteinuria algorithm.