<prompt> Which of the following diuretics decrease the renal lithium clearance?acetazolamidehydrochlorthiazidefurosemidespironolectone  <response>: Ans. is b i.e., hydrochlorothiazide Lithium has got low therapeutic index so measuring its plasma level is of utmost importance to assure safe use of drugApproximately 95 of a single dose of Li is eliminated in urine.Li is handled by the kidney in same way as Na i.e. most of the filtered Li is reabsorbed in the proximal tubule. So loading with Na will increase the Li excretion and Na depletion will promote a clinically important degree of retention of LiIt is now obvious that diuretics will cause retention of Li because they cause Na depletion.All the diuretics given in option except Acetazolamide decrease the renal lithium clearance.So we will have to choose the one, which causes the greatest retention of lithium.Goodman Gilman 10e, p 509 and Katzung 8e, p 493 write that the thiazide cause greatest retention among diuretics.Other drugs which can cause Li retentionTetracyclineIndomethacinACE inhibitors 