PURPOSE: The purposes of this study were to determine whether 1) proteinuria is induced by multiple days of wildland firefighting, and 2) there is a relationship between energy balance or hydration on the incidence of proteinuria (total protein, albumin, beta 2-microglobulin, N-acetyl-beta-D-glucosaminidase: NAG) during multiple days of wildland fire suppression.
METHODS: Eighteen male active-duty military personnel served as the subjects. All participants were randomly allocated to consume either First Strike Ration (FSR) (2,864 kcal, 377 g Carbohydrate, 91 g protein per day) or two Meals Ready to Eat (MRE)(2,620 kcal, 358 g Carbohydrate, 84 g protein per day) for three consecutive days. The activity during wildland firefighting was evaluated by accelerometer over a three-day experimental period. Body weight and urinary specific gravity were also measured to determine hydration status at pre- and post-work-shift for the three days. Urine was collected at pre- and post-work-shift of Day 1 and Day 3 to analyze the markers of proteinuria. Subsequently, all participants were divided into two groups consisting of minimal body weight loss (LOW-BWL) group (N=9) and higher body weight loss (HIGH-BWL) group (N=9).
RESULTS: There was a significantly lower caloric intake in HIGH-BWL (Day 1=2057.09±506.84; Day 2=2055.05±487.75; Day 3=1430.43±613.80 kcal/day) than LOW-BWL (Day 1= 2375.59±416.51; Day 2=2343.11±441.99; Day 3=1981.09±349.03 kcal/day) group (main effect for group, p<0.05), while similar activity counts were observed in both groups over a three-day period. When the markers of proteinuria were expressed relative to creatinine, neither the relationship between urinary total protein and albumin or % change in body weight (Day 1-Pre vs. Day 3-Post) were correlated (total protein: r=0.421, p=0.08; albumin: r=0.238, p=0.34). The percent change in body weight was well-correlated with urinary beta 2-microglobulin (r=0.596, p<0.01), NAG (r=0.552, p<0.05), creatinine (r=0.632, p<0.01) and specific gravity (r=0.556, p<0.05).
CONCLUSIONS: These results indicate that acute body weight loss as a function of negative energy balance during wildland firefighting may increase renal protein excretion.
Supported by Air Force Research Laboratories, FA 8650-06-1-679.