Background. The use of furosemide is well recognized as a predisposing fact
or of nephrocalcinosis in infants. Although furosemide is widely used for v
arious medical conditions in adults, its association with nephrocalcinosis
in adults is not well established.
Methods. We studied 18 consecutive adult patients (male : female ratio 1 :
17, age range 21-59 years) who habitually took furosemide to control weight
or oedema for long periods of time (range 3-25 years). The daily dose of c
ontinuous intake of furosemide ranged from 40 to 2800 mg. Nephrocalcinosis
was evaluated using renal ultrasonography (US), computed tomography (CT), o
r kidney biopsies.
Results. Renal US and CT revealed bilateral nephrocalcinosis of the medulla
ry pyramids in 15 (83.3%) out of 18 patients. The duration of furosemide ab
use was similar between nephrocalcinosis positive (NC(+)) and nephrocalcino
sis negative (NC(-)) groups. The daily dose of furosemide was nearly 10 tim
es higher in the NC(+) group (range 120-2800 mg, mean 538 mg) than the NC(-
) group (range 40-80 mg. mean 67 mg). All patients showed variable degrees
of renal insufficiency and there was no difference in creatinine clearance
between the NC(+) and NC(-) groups (P>0.05). Kidney biopsies performed in t
hree patients showed focal tubulo-interstitial fibrosis and atrophy and cal
cifications were observed in outer medullary tubulo-interstitium.
Conclusions. Long-term furosemide abuse can cause medullary nephrocalcinosi
s in adults, and the risk of developing of nephrocalcinosis seems to be cor
related with the daily dose of furosemide. We suggest that long-term furose
mide abuse should be suspected in adult patients when medullary nephrocalci
nosis is incidentally detected by US or CT.