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BASIC
AND TRANSLATIONAL UROLOGY
Shock
wave induced kidney injury promotes calcium oxalate deposition
Xue YQ, He DL, Chen XF, Li X, Zeng J, Wang XY
First Affiliated Hospital of Medical College, Xi’an Jiaotong University,
Xi’an, Shaanxi, China
J Urol. 2009; 182: 762-5
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Purpose:
Extracorporeal shock wave lithotripsy is the preferred treatment for
upper urinary tract renal calculi. However, this treatment is associated
with a high rate of recurrent renal calculi. Shock wave therapy can
result in renal epithelial cell injury, which in turn is a most important
factor in calculus formation. We investigated the influence of kidney
damage secondary to shock waves on Ca oxalate crystal retention in
the kidney.
Materials and Methods: A total of 32 rats were randomly divided into
4 groups, including group 1--controls, group 2--sham treated rats
given 25 ml 0.75% ethylene glycol per day for 14 days, group 3--rats
given 15 kV 1 Hz shock waves 500 times to the left kidney, followed
by 25 ml 0.75% ethylene glycol daily for 14 days, and group 4--rats
with the same treatment as group 3 except the number of impacts was
increased to 1,000. The 2 kidneys were removed at the end of the experiment.
Ca oxalate crystals were observed by surgical microscopy in kidney
sections stained with hematoxylin and eosin. Crystal morphology was
determined using polarizing microscopy. Acidified kidney tissue homogenate
was examined for Ca and oxalate content by colorimetry (Sigma).
Results: Kidney sections showed that kidneys that did not receive
shock waves had fewer crystals than kidneys with shock waves, which
had crystals in major areas. In the left kidney in groups 2 to 4 the
mean +/- SD quantity of Ca was 16.88 +/- 6.41, 28.58 +/- 7.54 and
40.81 +/- 15.29 micromol/gm wet kidney and the mean quantity of oxalate
was 8.44 +/- 6.80, 20.52 +/- 7.70, 31.76 +/- 14.14 micromol/gm wet
kidney, respectively. Ca oxalate density increased with the number
of shock wave impacts.
Conclusions: Kidney damage caused by shock wave treatment can increase
Ca oxalate crystal retention in the kidneys of rats in this stone
model.
- Editorial
Comment
The authors elegantly demonstrated in a rat model that shock wave
therapy results in proximal tubular injury in a dose dependent manner.
Also, this was associated with a markedly increased deposition of
CaOx stones in kidney tissue.
The study is provocative, since we know that extracorporeal shock
wave lithotripsy is associated with a high rate of stone recurrence.
The main shortcoming of the study is the use of a rat model, which
have a kidney very different from humans. Probably, further studies
in pigs, which have kidneys very similar to human kidney, would better
clarify this issue.
Dr.
Francisco J. B. Sampaio
Full-Professor and Chair, Urogenital Research Unit
State University of Rio de Janeiro
Rio de Janeiro, RJ, Brazil
E-mail: sampaio@urogenitalresearch.org
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