It has been reported that the use of orlistat can cause oxalate-induced
acute kidney injury (AKI). AKI was associated temporally with an
increased dose of orlistat and development of more frequent and oily stools (fat
Orlisat is an oral inhibitor of gastrointestinal lipase (pancreatic lipase) that
reduces the intestinal absorption of dietary fat and aids weight loss in obese
patients. Due to orlistat the unabsorbed dietary fat binds enteric calcium,
and reduces its ability to bind and isolate oxalate in the gut. This results in
absorption of free oxalate and its deposition in renal parenchyma.
To study the relation between orlistat and AKI, scientists studied urine
tests and kidney biopsy in the subjects. Abundant calcium oxalate crystals were
seen in the urine sediment. Urine reports also indicated increased 24-hour
urine oxalate concentration. On performing kidney biopsy, deposition of calcium
oxalate crystals was seen within tubular lumens.
A second kidney biopsy was done after a month of discontinuation of orlistat
therapy and increasing the oral fluid intake. The reports showed that there was
no deposition of calcium oxalate crystals within the tubules. Steady improvement
in the renal function was noted. 24-hour urine oxalate collection was within
the normal range. Thus the findings prove that orlistat use can be associated
with AKI, especially among those with underlying chronic kidney disease.