Protein Requirements

Proteins are body’s structural building blocks, they do provide energy but that is not their primary purpose. Each gram of protein can provide 4 kcal of energy, but this process is undesirable, the protein should be used for tissue building and not for energy production. This is why pharmacists try to fill all of the patients calorie needs with nonprotein calories. The daily protein requirements in adults are generally estimated to be:

• 0.8 g/kg/day for normal, unstressed patients
• 1-1.2 g/kg/day for hospitalized patients
• 1.5-2 g/kg/day for stressed patient (critical illness, infection or trauma)

The standard source of proteins in TPN is amino acids. They come in 5.5, 8.5, 10 and 15 % concentrations.

Solved Problem: : A TPN solution will supply 600 ml of 15% amino acid. How many grams of protein and kcal are supplied by the amino acids? Approach: : 1 gram of protein provides with 4 kcal, set up a proportion to calculate grams of protein in 600 ml of solution and then multiply it with 4 kcal. $$ {15 \ g \over 100 \ ml }= {x \ g \over 600 \ ml}; x = 90 \ g $$ $$ {4 \ kcal \over g } \times 90 \ g = 360 \ kcal $$ Answer: 90 grams, 360 kcal