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STONE
DISEASE
Jejunoileal
bypass reversal: effect on renal function, metabolic parameters and stone
formation
Dhar NB, Grundfest S, Jones JS, Streem SB
Glickman Urological Institute, Cleveland Clinic Foundation, Cleveland,
Ohio, USA
J Urol. 2005; 174: 1844-6; discussion 1846
- Purpose:
While the effect of jejunoileal bypass (JIB) reversal has been well
studied regarding hepatic function, there is little information regarding
the effect of reversal on renal function and even less data regarding
the metabolic urinary stone environment. We evaluated the results of
JIB reversal on renal function, the urinary stone milieu and the clinical
development of recurrent calculi in affected patients.
- Materials
and Methods: From 1995 to 2003, 4 female patients with a mean
age of 48.2 years underwent JIB reversal primarily for refractory stone
disease. The clinical and metabolic courses prior to and following bypass
reversal were reviewed specifically to evaluate renal function, serum
and urinary metabolic stone profiles, and clinical stone formation.
- Results:
At initial presentation following JIB all 4 patients had significantly
increased 24-hour urinary oxalate (range 80 to 160 mg, mean 112.5, normal
less than 50) and significantly low 24-hour urinary citrate (range 5
to 62 mg, mean 21.5, normal greater than 320). Following reversal 24-hour
urinary oxalate normalized to between 31 and 36 mg (mean 33.75). However,
24-hour urinary citrate continued to be low (range 215 to 248 mg, mean
226.5). After JIB reversal all 4 patients continued to have new stones
until the commencement of urinary alkalization, following which only
1 had 1 calculus, which occurred 47 months after reversal. After JIB
mean serum creatinine was 1.48 mg/dl (range 0.8 to 1.9) and mean urinary
creatinine excretion was 0.91 mg per hour (range 0.69 to 1.15). After
JIB reversal mean serum creatinine was 1.28 mg/dl (range 0.6 to 2.0)
and mean urinary creatinine excretion was 1.0 mg per hour (range 0.85
to 1.10).
- Conclusions:
JIB reversal normalizes 24-hour urinary oxalate. While urinary citrate
improves, it continues to be low and such patients are at high risk
for recurrent stone formation. However, in this setting appropriate
replacement therapy has a significant and positive impact on that propensity.
- Editorial
Comment
Bone loss, liver disease and renal calculi are only a few of the metabolic
consequences of jejunoileal bypass. Stones form as a consequence of
hyperoxalauria, low urine volume and pH and hypocitraturia that occur
because of metabolic acidosis and malabsorption. Stone disease in some
patients has been severe enough to prompt JI bypass reversal. Dhar and
colleagues seized a unique opportunity to study 4 such patients before
and after JI bypass reversal. They documented a significant reduction
in stone formation rate, from 3.2 to 0.19 stones/patient/year after
bypass reversal. Of note, however, reversal of the JI bypass failed
to completely reverse the marked hypocitraturia associated with bypass
surgery that is due to severe metabolic acidosis. Initiation of alkalinization
with potassium citrate, however, led to complete cessation of stone
formation in all but 1 of the 4 patients, who produced a single stone.
These findings are particularly relevant as laparoscopic intestinal
bypass surgery has become increasingly popular. We should heed the lessons
learned from JI bypass surgery and take a proactive approach to avert
the metabolic consequences of intestinal surgery, and further, to continue
to follow patients after bypass reversal since their risks may not completely
reverse without pharmacologic intervention.
Dr.
Margaret S. Pearle
Associate Professor of Urology
University of Texas Southwestern Med Ctr
Dallas, Texas, USA |