Optimizing a kidney stress test to evaluate renal functional reserve.
BACKGROUND
Renal function reserve (RFR) describes the capacity of the kidney to increase glomerular filtration rate (GFR) in response to physiological or pathological stimuli. The scope of our study was to evaluate the optimal level of stimulation using different doses of protein load (PL) for a standard renal stress test (RST).


METHODS
18 young healthy individuals were given sessions of PL with 1 and 2 g/kg body weight. Endogenous creatinine clearance was calculated. Baseline GFR (bGFR) and stress GFR (sGFR) (post-PL) were obtained; RFR is the difference between stress and baseline GFR. A p-value < 0.05 was considered statistically significant.


RESULTS
Mean bGFR was 107.97 ± 12.33 mL/min/1.73m2. sGFR with 1 and 2 g PL were significantly higher than bGFR in all subjects. The sGFR after 2 g PL (141.75 ± 19.90 mL/min/1.73m2) was not statistically different from the sGFR after 1 g PL (142.37 ± 22.35 mL/min/1.73m2). sGFR and therefore RFR were independent from the value of bGFR.


CONCLUSIONS
We found no difference between 1 and 2 g/kg body weight PL to elicit sGFR. RST may be useful to predict susceptibility and risk of developing acute kidney injury and/or progression to chronic kidney disease. RST uncovers the possible loss of renal functional mass when this condition is not manifested clinically. Further studies are needed to set this hypothesis.
Aashish
A
Sharma
Jose J
JJ
Zaragoza
Gianluca
G
Villa
Leonardo C
LC
Ribeiro
Renhua
R
Lu
Marco
M
Sartori
Elena
E
Faggiana
Massimo
M
de Cal
Grazia M
GM
Virzi
Valentina
V
Corradi
Alessandra
A
Brocca
Faeq
F
Husain-Syed
Alessandra
A
Brendolan
Claudio
C
Ronco
D000328:Adult; D003404:Creatinine / Q000097:blood / Q000652:urine; D005260:Female; D005919:Glomerular Filtration Rate; D064368:Healthy Volunteers; D006801:Humans; D007668:Kidney / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011506:Proteins / Q000008:administration & dosage*; D055815:Young Adult
D011506:Proteins; D003404:Creatinine