 ### Description

The protein catabolic rate (PCR) for a patient can be calculated once the urea generation rate (G or Gu) is known. This method assumes no dialysis during the time period and no nonurinary urea loss.

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)