qqq..............................................3 - ariadnac06 - Printable Version +- USMLE Forum - Largest USMLE Community (https://www.usmleforum.com) +-- Forum: USMLE Forum (https://www.usmleforum.com/forumdisplay.php?fid=1) +--- Forum: Step 1 (https://www.usmleforum.com/forumdisplay.php?fid=2) +--- Thread: qqq..............................................3 - ariadnac06 (/showthread.php?tid=505031) |
qqq..............................................3 - ariadnac06 - ArchivalUser - 05-08-2010 A 10-year-old child develops severe, colicky, flank pain. Urinalysis shows yellow-brown hexagonal crystals. An abdominal x-ray film demonstrates radiopaque staghorn calculi of both renal pelvises. The nitroprusside cyanide test on urine is positive. Which of the following is the most likely diagnosis? A. Cystinuria B. Familial iminoglycinuria C. Fanconi syndrome D. Hartnup disease E. Hypophosphatemic rickets 0 - ArchivalUser - 05-08-2010 A. Cystinuria 0 - ArchivalUser - 05-08-2010 A? 0 - ArchivalUser - 05-08-2010 Cystinurea is an autosomal recessive, defect in proximal tubular reabsorption of cystine 0 - ArchivalUser - 05-08-2010 AAA ? 0 - ArchivalUser - 05-08-2010 The correct answer is A. This is cystinuria, which is an autosomal recessive defect of the renal tubules in which the amino acid cystine cannot be resorbed. The cystine often precipitates in the urine, forming radiopaque stones (because of enough coprecipitation with calcium) in the bladder or renal pelvis. The renal pelvis stones often take the form of staghorn calculi. Isolated crystals of cystine have a characteristic yellow-brown, hexagonal morphology that can be identified in urine specimens. A positive nitroprusside cyanide test on urine will confirm the diagnosis. Alkalinization of the urine significantly increases the solubility of the cystine, and is used with high fluid intake as the mainstay of therapy. However, eventual development of end-stage renal failure is common. Familial iminoglycinuria (choice B) is characterized by impaired renal tubular resorption of proline, hydroxyproline, and glycine. Fanconi syndrome (choice C) is characterized by glucosuria, phosphaturia, aminoaciduria, and bicarbonate wasting. Hartnup disease (choice D) is characterized by a generalized aminoaciduria and more specific abnormalities of tryptophan metabolism. Hypophosphatemic rickets (choice E) is characterized by decreased proximal renal tubular resorption of phosphate and bony abnormalities 0 - ArchivalUser - 04-06-2012 nice question >>>> deserves reposting |