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Triamterene Kidney Stones
FaDI I. Jabr, mD
A64-year-old woman with a history of recur- rent kidney stones presented with severe left flank pain radiating to the left lower quadrant of 4 days’ duration. She brought that she had passed in urine. Her medications included hydrochlorothiazide, 25 mg/triamterene, 37.5 mg.
An abdominal radiograph (A) and a CT scan of the
kidneys, ureters, and bladder (B) showed bilateral renal
calcifications. On the right, the largest was 3 mm, and on the left, multiple punctate calcifications were evident. Urinalysis was positive for trace blood and trace leuko- cytes. The analysis of the stone revealed triamterene composition. The patient underwent successful place- ment of ureteral stents to help passage of the stones fol- nucleus of the stone or was deposited with calcium In the 1970s, triamterene was the major cause of oxalate or uric acid; this finding suggests that in the drug-induced renal calculi.1 In a 1980 study, the estimat- majority of cases, triamterene lithiasis develops in per- ed annual incidence of triamterene lithiasis was 1 per sons who have had renal stones.2 It becomes incorpo- 1500 users of triamterene/hydrochlorothiazide.2 Triam- rated into existing stone nidi by binding to the protein terene was found in 0.4% (181 of 50,000) of renal calculi submitted for analysis.2 This percentage has probably Treatment consists of discontinuation of the medi- changed in recent years because indinavir and sulfadia- cation and lithotripsy, because the calculi cannot be zine are now the most common causes of drug-contain- dissolved by pH manipulation.3 On plain radiographs, ing renal stones.1,3 Triamterene is still responsible, how- triamterene stones are—as in this case—faintly radio- ever, for many drug-induced calculi.
paque and are less dense than calcium oxalate stones. Both unchanged triamterene and its metabolites, They are more detectable on a CT scan of the kidneys, hydroxytriamterene and sulfate ester of hydroxytriam- terene, are present in triamterene stones.4 Up to one This case illustrates the need to be cautious in the third of triameterene stones consist entirely of triam- use of triamterene, particularly in patients who are pre- terene.2,5 In the remainder, triameterene formed the disposed to nephrolithiasis or who have a prior history of kidney stones, to avoid the formation of new calculi. This caution applies even when triamterene is used in REFERENCES:
1. Daudon M, Jungers P. Drug-induced renal calculi: epidemiology, prevention
and management. Drugs. 2004;64:245-275.
2. Ettinger B, Oldroyd NO, Sorgel F. Triamterene nephrolithiasis. JAMA.
3. Matlaga BR, Shah OD, Assimos DG. Drug-induced urinary calculi. Rev Urol.
4. Sorgel F, Ettinger B, Benet LZ. The true composition of kidney stones passed
during triamtrene therapy. J Urol. 1985;134:871-873.
5. Carr MC, Prien EL Jr, Babayan RK. Triamterene nephrolithiasis: renewed
attention is warranted. J Urol. 1990;144:1339-1340.
6. Werness PG, Bergert JH, Smith LH. Triamterene urolithiaisis: solubility, pH,
effect on crystal formation, and matrix binding of triamterene and its metabolites. J Lab Clin Med. 1982;99:254-262.
658 Consultant september 2011

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