Calculating Urea Generation Rate
total body urea at beginning of period in grams =
= ((total body water in liters) + (liters of edema fluid in liters)) * (serum urea nitrogen in mg/dL) * (10)
total body urea at end of period in grams =
= ((total body water in liters) + (liters of edema fluid in liters)) * (serum urea nitrogen in mg/dL) * (10)
daily urea loss in urine during period in grams =
= (24 hour urine volume in liters) * (urine urea nitrogen in mg/dL) * 10
where:
• 10 is conversion of mg/dL urea to mg/L
• usual beginning for period is just after a dialysis session
• usual end of period is just before the next dialysis session
urea generation per day in grams/day =
= (((total body urea at end of period) - (total body urea at beginning of period)) / (number of days in period)) + (urinary urea loss in grams/day)
Calculating Protein Catabolic Rate
Since (from Sargent)
urea generation in grams per day =
= (0.154 * (protein catabolic rate)) - 1.7
protein catabolic rate in grams per day =
= ((urea generation rate in grams per day) + 1.7) / 0.154
normalized protein catabolic rate in grams/kilograms/day =
= (protein catabolic rate) / (body weight in kilograms)
