Case-letter| Volume 351, ISSUE 2, P213-214, February 2016

Efavirenz-Associated Urinary Matrix Stone—A Rare Presentation

      Renal stones are a relatively common problem in the United States. The lifetime risk for renal stones is estimated to be 10-15% with an estimated recurrence rate of 50% over 10 years. The usual renal stones consist predominantly of crystalline components such as calcium oxalate, calcium phosphate, uric acid and magnesium ammonium phosphate and a small amount of matrix which accounts for less than 2.5% organic matrix by weight. The matrix consists predominantly of various proteins and some mucopolysaccharides. However, in rare cases, the patients form “matrix stones” in which the matrix contributes to approximately 65% of the dry weight on average with values ranging from 42-84% and contain no or only a small amount of crystalline components.
      • Liu C.C.
      • Li C.C.
      • Shih M.
      • et al.
      Matrix stone.
      The composition of the matrix substance found in the usual crystalline stones is similar to that found in matrix stones. Efavirenz, a non-nucleoside reverse-transcriptase inhibitor, is a commonly used antiretroviral agent. We report a case of Efavirenz-associated matrix stone, an uncommon and rare form of kidney stone in a human immunodeficiency virus (HIV)-positive patient with recurrent Escherichia coli (E. coli) urinary tract infections.
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