Estimated lean body mass is more appropriate than body surface area for scaling glomerular filtration rate and extracellular fluid volume

Nephron Clin Pract. 2010;116(1):c75-80. doi: 10.1159/000314666. Epub 2010 May 21.

Abstract

Background/aims: To compare body surface area (BSA) with lean body mass (LBM) for scaling extracellular fluid volume (ECV) and glomerular filtration rate (GFR).

Methods: Phase 1: Total body water (TBW), bromide space and LBM were measured with (3)H-water, (77)Br and dual X-ray absorptiometry, respectively, in 6 healthy adults. Phase 2: ECV and GFR were measured with (51)Cr-EDTA in 95 healthy adults and 56 children (0.5-13 years). ECV was calculated as GFR divided by GFR/ECV, both corrected for the one-compartment assumption. LBM was estimated (eLBM) in adults from height and weight and in children using a height/weight formula for estimating ECV and a constant derived from a separate adult population relating ECV to eLBM.

Results: Phase 1: LBM and BSA correlated closely with TBW and bromide space. With LBM, the regressions passed through the origin, but with BSA, the intercepts were significantly below zero. Phase 2: GFR/BSA and ECV/BSA were higher in men than women but no difference was recorded in GFR/eLBM, GFR/ECV or ECV/eLBM. ECV showed a linear relation with eLBM and a non-linear relation with BSA. GFR/BSA and ECV/BSA correlated significantly with BSA but neither GFR/eLBM nor ECV/eLBM correlated with eLBM.

Conclusion: eLBM is preferable to BSA for scaling GFR and ECV.

Publication types

  • Comparative Study

MeSH terms

  • Absorptiometry, Photon
  • Adult
  • Aged
  • Body Fluids / physiology
  • Body Mass Index*
  • Body Surface Area*
  • Child
  • Child, Preschool
  • Extracellular Fluid / physiology*
  • Female
  • Glomerular Filtration Rate / physiology*
  • Humans
  • Male
  • Middle Aged
  • Thinness* / physiopathology
  • Young Adult