Are we overfeeding hemodialysis patients with protein? Exploring an alternative method to estimate protein needs

Abstract

Background & aims: Sufficient protein intake is of great importance in hemodialysis (HD) patients, especially for maintaining muscle mass. Daily protein needs are generally estimated using bodyweight (BW), in which individual differences in body composition are not accounted for. As body protein mass is best represented by fat free mass (FFM), there is a rationale to apply FFM instead of BW. The agreement between both estimations is unclear. Therefore, the aim of this study is to compare protein needs based on either FFM or BW in HD patients. Methods: Protein needs were estimated in 115 HD patients by three different equations; FFM, BW and BW adjusted for low or high BMI. FFM was measured by multi-frequency bioelectrical impedance spectroscopy and considered the reference method. Estimations of FFM x 1.5 g/kg and FFM x 1.9 g/kg were compared with (adjusted)BW x 1.2 and x 1.5, respectively. Differences were assessed with repeated measures ANOVA and BlandeAltman plots. Results: Mean protein needs estimated by (adjusted)BW were higher compared to those based on FFM, across all BMI categories (P < 0.01) and most explicitly in obese patients. In females with BMI >30, protein needs were 69 ± 17.4 g/day higher based on BW and 45 ± 9.3 g/day higher based on BMI adjusted BW, compared to FFM. In males with BMI >30, protein needs were 51 ± 20.4 g/day and 23 ± 20.9 g/day higher compared to FFM, respectively. Conclusions: Our data show large differences and possible overestimations of protein needs when comparing BW to FFM. We emphasize the importance of more research and discussion on this topic.

Protein requirements and provision in hospitalised COVID-19 ward and ICU patients: Agreement between calculations based on body weight and height, and measured bioimpedance lean body mass

“…Therefore, using targets set to LBM based on mathematical methods or TBW is likely to lead to significant over-or underdosing of protein in all other groups. This is in line with findings in other patient categories [16,18].…”

“…Thus, the LBM 27.5 method becomes more realistic as actual BMI increases (up to a certain point), explaining the proportional bias that can be seen in Fig. 1 adjusted to BMI ¼ 27.5) in 115 hemodialysis patients and concluded that mean protein needs estimated by (adjusted) TBW were higher than those based on LBM BIA , across all BMI categories (P < .01), and most explicitly in obese patients [18]. This overestimation occurred eventhough a correction factor in grams/kg was used (LBM BIA * 1.5, whereas (adjusted) TBW * 1.2).…”

Calculation of protein requirements; a comparison of calculations based on bodyweight and fat free mass

“…Two articles were published and discussed comparing protein requirements calculation based on bodyweight and FFM. In both studies, a large underand overestimation in protein requirements was seen when using bodyweight, especially in participants with under-and overweight [8,9]. To continue this discussion, the answer is sought in a large population to the following question: Will choosing actual bodyweight, corrected bodyweight or FFM to calculate protein requirements result in clinically relevant differences?…”

Kommentar zu Körpergewicht oder Fett-freie Masse als Bezugsgröße für die Berechnung des Proteinbedarfs

“…In Ermangelung einer wirklichen Referenz (=die Bestimmung des tatsächlichen Proteinbedarfs anhand einer systematischen Analyse der Stickstoffbilanz) ist die Bedeutung der mitgeteilten Ergebnisse zunächst endlich. Allerdings ist die untersuchte Fragestellung bisher wenig beachtet worden: die Autor*innen verweisen auf lediglich 3 Studien, die bisher zu diesem Thema publiziert worden sind 2 3 4 , eine weitere Studie haben sie übersehen 5 .…”

“…In dieser Studie wurde der Proteinbedarf mit 1,2 g/kg Körpergewicht (bzw. bei Untergewicht und Adipositas mit dem jeweils korrigierten Körpergewicht) und [2][3][4], eine weitere Studie haben sie übersehen [5].…”