 # How to Quickly Solve This Tricky TPN Calculations Question

Posted on Posted in NAPLEX®, Pharmaceutical Calculations

Total Parenteral Nutrition (TPN) calculations can be complex and typically involve several steps. Often, one is required to calculate quantities of macro- and micro-nutrients for a given patient. Determining amounts of macro-nutrients such as proteins, carbohydrates and lipids involve using equations, calculating calories, computing weights of ingredients and figuring out appropriate volumes.

Processing all this information correctly could potentially be overwhelming to students when first exposed to TPN calculations. In contrast, calculating amounts of micro-nutrients is simply a matter of proportions.

However, there are a few instances where even those types of TPN calculations are not as easy as they seem. Here is one tricky TPN calculations question that trips several students. You would find the question below. Attempt it first, check the video solution when you are done and let’s take another giant step to dominating pharmaceutical calculations.

## Question

1 Liter of TPN solution is to contain 80 mEq of sodium and 30 mEq of acetate. Available stock solutions contain 4 mEq/mL of sodium as sodium chloride and 2 mEq/mL of sodium as acetate. How many milliliters of sodium chloride stock solution are needed?

## Solution

So what do you think? Did the question trip you too? Great job if you got it right. I’m sure some of you were able to solve it using a totally different approach. Either way, share your thoughts in the comments box below.