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. 2025 Apr 8;17(8):1293.
doi: 10.3390/nu17081293.

The Impact of Protein Feed on the Urea-to-Creatinine Ratio-A Retrospective Single-Center Study

Petra Hillinger  1 , Andreas Markl-Le Levé  1 , Simon Woyke  1 , Marco Ronzani  1 , Janett Kreutziger  1 , Stefan Schmid  1 , Christopher Rugg  1
Affiliations

The Impact of Protein Feed on the Urea-to-Creatinine Ratio-A Retrospective Single-Center Study

Petra Hillinger et al. Nutrients. .

Abstract

Background/objectives: The urea-to-creatinine ratio (UCR) serves as a biochemical marker for catabolism in the intensive care unit (ICU). UCR increases mainly due to an elevated urea generation from increased protein metabolism. This study aimed to evaluate the impact of protein intake on UCR progression in ICU patients.

Methods: The inclusion criteria of this retrospective, single-center analysis required an ICU stay of at least 14 days without requirement of renal replacement therapy (n = 346 patients). Patients were grouped based on daily mean protein intake per kilogram between days 5 and 14: low (≤0.8 g/kg/d, n = 120), medium (0.9-1.2 g/kg/d, n = 132), and high (≥1.3 g/kg/d, n = 94). Data on daily protein and calorie intake, calorie deficit, urea generation rate, serum creatinine, urea, UCR and creatinine clearances were analysed. Risk factors for developing a high UCR were determined via logistic regression analysis adjusted for sex, age, bodyweight, disease severity (SAPS III admission score) as well as mean protein intake and calorie deficit during day 5 and 14 on ICU.

Results: Higher protein intake was associated with increased calorie intake, lower calorie deficit, and led to an elevated urea generation rate and higher UCR. Renal function and serum urea trends were comparable between all groups, while creatinine was significantly lower in the high-protein group. Risk factors for developing an elevated UCR included older age, female sex and higher protein intake.

Conclusions: An elevated UCR in the early ICU phase may indicate an increased protein metabolism, not only deriving from catabolism but also from a high protein feed.

Keywords: catabolism; protein metabolism; urea-to-creatinine-ratio.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Group dependent presentation of daily protein intake, calorie intake, calorie deficit and urea generation rate. Lines represent daily medians, vertical error bars the interquartile range. Calorie deficit is calculated as difference between energy expenditure (generated from ventilator derived VCO2) and total calorie intake. Urea generation rate is calculated as sum of total urinary urea excretion and body urea variation (difference in serum urea and serum urea the day before multiplied with 0.6 times the bodyweight). For better comparison, the urea generation rate was normalized to 70 kg by dividing the urea generation rate with the patient’s bodyweight and multiplying the result with 70 kg.
Figure 2
Figure 2
Group dependent presentation of serum creatinine, creatinine clearance, serum urea and serum urea-to-creatinine ratio. Lines represent daily medians, vertical error bars the interquartile range. Creatinine clearance was measured by full 24-h urine collection and then normalized to 1.73 m2 body surface area by dividing the measured creatinine clearance with the patient’s actual body surface area and multiplying the result with 1.73 m2.
See this image and copyright information in PMC

References

    1. Rosenthal M.D., Moore F.A. Persistent Inflammatory, Immunosuppressed, Catabolic Syndrome (PICS): A New Phenotype of Multiple Organ Failure. J. Adv. Nutr. Hum. Metab. 2015;1:e784. doi: 10.14800/janhm.784. - DOI - PMC - PubMed
    1. Hesselink L., Hoepelman R.J., Spijkerman R., de Groot M.C.H., van Wessem K.J.P., Koenderman L., Leenen L.P.H., Hietbrink F. Persistent Inflammation, Immunosuppression and Catabolism Syndrome (PICS) after Polytrauma: A Rare Syndrome with Major Consequences. J. Clin. Med. 2020;9:191. doi: 10.3390/jcm9010191. - DOI - PMC - PubMed
    1. Puthucheary Z.A., Rawal J., McPhail M., Connolly B., Ratnayake G., Chan P., Hopkinson N.S., Phadke R., Dew T., Sidhu P.S., et al. Acute Skeletal Muscle Wasting in Critical Illness. JAMA. 2013;310:1591–1600. doi: 10.1001/jama.2013.278481. - DOI - PubMed
    1. Fazzini B., Märkl T., Costas C., Blobner M., Schaller S.J., Prowle J., Puthucheary Z., Wackerhage H. The Rate and Assessment of Muscle Wasting during Critical Illness: A Systematic Review and Meta-Analysis. Crit. Care. 2023;27:2. doi: 10.1186/s13054-022-04253-0. - DOI - PMC - PubMed
    1. Ali N.A., O’Brien J.M., Hoffmann S.P., Phillips G., Garland A., Finley J.C.W., Almoosa K., Hejal R., Wolf K.M., Lemeshow S., et al. Acquired Weakness, Handgrip Strength, and Mortality in Critically Ill Patients. Am. J. Respir. Crit. Care Med. 2008;178:261–268. doi: 10.1164/rccm.200712-1829oc. - DOI - PubMed

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