TPN Macronutrient Calculator
Total parenteral nutrition tool
ClinCalc.com » Nutrition » Total Parenteral Nutrition (TPN) Macronutrient Calculator
Press 'Calculate' to view calculation results.
About This Calculator
This total parenteral nutrition calculator provides an empiric dose for the macronutrients included in a TPN formulation. In addition to providing an initial recommended dose, you may alter the contents of each macronutrient while maintaining a specified daily caloric requirement.
This calculator is not appropriate for the following patient populations, or may require a higher degree of clinical judgment:
- At risk for refeeding syndrome
- Concurrent enteral nutrition
- Impaired fluid management (hypervolemia, CHF)
Macronutrient Caloric Density
The following macronutrient caloric density are used for calculations:
Initial fluid requirement estimation
The initial fluid requirement estimation is calculated using the following equation (note that volumes are cumulative):2
|First 10 kg ||100 mL/kg
|10-20 kg ||50 mL/kg
|Weight > 20 kg ||20 mL/kg
As a shortcut for patients weighing at least 20 kg, the equation may be rewritten as:
$$\\ Fluid\;requirement\;(mL/day) = 1500\;mL + \\ [(Weight\;above\;20\;kg) * 20\;mL/kg]$$
Nutritional weight calculation
There is a significant amount of controversy regarding the nutritional requirements of obese patients.3 If one uses an ideal body weight, the true nutritional requirements of an obese patient are underestimated. In contrast, the use of actual body weight will result in an overestimation of caloric requirements.
This calculator uses a correction adjustment of 25% (see equation below); however, it is important to note that a higher correction coefficient (ie, 50%) may be appropriate for patients on chronic TPN when the goal is to provide full calories.
$$\\ Nutritional\;weight = IdealBW + 0.25*(ActualBW - IdealBW)$$
An osmolarity calculation may be useful for determining whether a patient's TPN requires a central line (>900 mOsm/L) or if it may be infused via a peripheral line (eg, "peripheral parenteral nutrition", or PPN).1 Note that the osmolarity calculation included in this calculator does not account for electrolytes, which will significantly contribute to a formulation's osmolarity.
References and Additional Reading
- Pittiruti M, Hamilton H, Biffi R, et al. ESPEN Guidelines on Parenteral Nutrition: central venous catheters (access, care, diagnosis and therapy of complications). Clin Nutr. 2009;28(4):365-77. PMID 19464090.
- Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957;19(5):823-32. PMID 13431307.
- Krenitsky J. Adjusted body weight, pro: evidence to support the use of adjusted body weight in calculating calorie requirements. Nutr Clin Pract. 2005;20(4):468-73. PMID 16207686.