Serum creatinine may be elevated in the setting of normal renal function. Etiologies include decreased creatinine excretion, increased production creatinine, consumption of excess quantities of creatine and interference with laboratory assays. What drugs are implicated as a cause of reduced tubular secretion of creatinine?
Creatinine is filtered by the glomeruli and not reabsorbed. In addition to glomerular filtration, about 10-15% of the excreted creatinine is secreted by the renal tubules. The following drugs interfere with excretion of creatinine by renal tubules: trimethoprim, cimetidine, pyrimethamine, and salicylates. Salicylates may impact renal perfusion and reduce GFR and creatinine clearance by that mechanism as well. Other H2 antagonists such as famotidine and ranitidine do not appear to cause reduced creatinine secretion by renal tubules (at least at usual doses).
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Submitted by: Michael Hodgman MD on behalf of the Herbal and Dietary Supplement Section