Protein Catabolism Calculator
Estimates the normalized protein catabolic rate (nPCR) for stable patients who undergo dialysis.
In the text below the tool you can find the formula used and more information about the factors that affect protein catabolism.
The protein catabolism calculator determines the normalized protein catabolic rate (nPCR) which is used in the evaluation of dietary protein intake for patients under dialysis.
PCR is a parameter measured monthly within hemodialysis units and varies directly with the Kt/V.
The two nPCR formulas are:
■ nPCR Anuric = 0.22 + (0.864 x (ID BUN rise in mg/dL)/(ID hours))
■ nPCR Total = nPCR Anuric + (Urine urea nitrogen in g x 150)/(ID hours x Weight in kg)
These measure the interdialytic appearance of urea in body fluids and account for any urea lost during residual renal function.
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Steps on how to print your input & results:
1. Fill in the calculator/tool with your values and/or your answer choices and press Calculate.
2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.
Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.
Variables and formulas
There are four factors that contribute to the protein catabolism determination, as explained in the table below:
| Variables | Description |
| Patient weight | Weight provides information on nourishment status, any possible weight loss or gain and refines the nPCR Anuric value. |
| ID hours | Refers to the interdialytic period in hours. |
| ID BUN rise | The registered change in blood urea nitrogen during the interdialytic period. |
| Urine urea nitrogen | Refers to the total amount of urea nitrogen excreted during the interdialytic period. |
Blood urea nitrogen is one of the main renal function parameters. BUN normal values are 6 – 20 mg/dL (1.8 – 7.1 mmol/L).
Causes for high BUN include high protein diet or decrease in GFR. Low BUN levels are consistent with severe liver disease or antidiuretic hormone dysfunction.
When urine urea nitrogen is lower than 12-20 g per 24 hours, nephrologic problems or malnutrition can be suspected.
The two nPCR formulas used are:
nPCR Anuric = 0.22 + (0.864 x (ID BUN rise in mg/dL) / (ID hours))
nPCR Total = nPCR Anuric + (Urine urea nitrogen in g x 150) / (ID hours x Weight in kg)
nPCR measures the interdialytic appearance of urea in body fluids. The formulas also account for urea losses during residual renal function.
About PCR analysis
Determining the PCR helps distinguish between patients who are adequately dialyzed (and who maintain a healthy protein intake) and patients with a decreased protein intake, as reflection of inadequate dialysis.
PCR values vary directly with Kt/V and are the protein equivalent of nitrogen appearance (PNA). The PCR analysis is performed monthly for dialysis patients, however, it can only be performed on patients who are metabolically stable.
Also there is criticism that this measurement frequency does not reflect daily changes in protein intake and does not reflect outcome.
According to the National Cooperative Dialysis Study (NCDS), PCR values greater than 1 g/kg/day were found to be associated with lower morbidity.
References
1. Garred LJ, Tang W, Barichello DL, Canaud B. Equations for the calculation of the protein catabolic rate from predialysis and postdialysis urea concentrations and residual renal clearance in stable hemodialysis patients. Blood Purif. 1997; 15(3):157-68.
2. Panzetta G, Tessitore N, Faccini G, Maschio G. The protein catabolic rate as a measure of protein intake in dialysis patients: usefulness and limits. Nephrol Dial Transplant. 1990; 5 Suppl 1:125-7.
3. Sherman RA, Cody RP, Rogers ME, Solanchick JC. Accuracy of the urea reduction ratio in predicting dialysis delivery. Kidney International. 1995; (47)1: 319-321.
Specialty: Nutrition
System: Digestive
Objective: Determination
Type: Calculator
No. Of Variables: 4
Article By: Denise Nedea
Published On: May 27, 2017 · 08:52 AM
Last Checked: May 27, 2017
Next Review: May 27, 2023