Validity of surrogate measures for functional nephron mass.
BACKGROUND
Transplanted nephron mass is an important determinant of long-term allograft survival, but accurate assessment before organ retrieval is challenging. Newer radiologic imaging techniques allow for better determination of total kidney and cortical volumes.


METHODS
Using volume measurements reconstructed from magnetic resonance or computed tomography imaging from living donor candidates, we characterized total kidney (n=312) and cortical volumes (n=236) according to sex, age, weight, height, body mass index (BMI), and body surface area (BSA).


RESULTS
The mean cortical volume was 204 mL (range 105-355 mL) with no significant differences between left and right cortical volumes. The degree to which existing anthropomorphic surrogates predict nephron mass was quantified, and a diligent attempt was made to derive a better surrogate model for nephron mass. Cortical volumes were strongly associated with sex and BSA, but not with weight, height, or BMI. Four prediction models for cortical volume constructed using combinations of age, sex, race, weight, and height were compared with models including either BSA or BMI.


CONCLUSIONS
Among existing surrogate measures, BSA was superior to BMI in predicting renal cortical volume. We were able to construct a statistically superior proxy for cortical volume, but whether relevant improvements in predictive accuracy could be gained needs further evaluation in a larger population.
Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA. jane.tan@stanford.edu
Jane C
JC
Tan
Jane
J
Paik
Glenn M
GM
Chertow
F Carl
FC
Grumet
Stéphan
S
Busque
Jessica
J
Lapasia
Manisha
M
Desai
D015992:Body Mass Index; D001830:Body Surface Area; D001835:Body Weight; D006801:Humans; D007668:Kidney / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D016030:Kidney Transplantation; D019520:Living Donors; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009399:Nephrons / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000637:transplantation; D009929:Organ Size; D015203:Reproducibility of Results; D020858:Tissue and Organ Harvesting / Q000592:standards; D014057:Tomography, X-Ray Computed; D019737:Transplants / Q000592:standards