Reviewers: Nikhil Sangle, M.D. (see Reviewers page)
Revised: 26 December 2012, last major update September 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.
● Stones within collecting system of kidney are present in 5-10% of Americans; most commonly in men ages 20-49
● Due to supersaturation of stone constituents, decreased urine volume or deficiency of crystal inhibitors in urine
● 80% unilateral, usually in calyces, pelvis or bladder
● Usually only 2-3 mm, but with severe, abrupt flank pain and hematuria
● All stones contain an organic matrix of mucoprotein
Types of stones
● Calcium oxalate / phosphate (75%): due to hypercalciuria (idiopathic, 50%), hypercalcemia (infants may have high Vitamin D levels, Iran J Kidney Dis 2012;6:186), hyperoxaluria (in vegetarians with oxalate rich diet), hyperuricosuria (hyperparathyroidism, bone disease, sarcoidosis) and rarely primary hyperoxaluria (Arch Pathol Lab Med 2002;126:1250); oxalate crystals are highlighted by polarized light; are accompanied by foreign body giant cells and macrophages
● Struvite (triple stones, magnesium ammonium phosphate, 15%): due to urea-splitting bacteria (Proteus, Staphylococcus); produce staghorn calculi
● Uric acid (6%): due to hyperuricemia, chemotherapy for leukemia, uricosuric drugs or excess dietary proteins; 50% lack elevated uric acid in blood / urine; may be due to acidic pH; radiolucent; may become staghorn calculi if in renal pelvis; elongated and rectangular crystals in collecting tubules or doubly refractile crystals in interstitium with giant cell reaction
● Cysteine (1%): due to genetic defects in cystine transport (Orphanet J Rare Dis 2012;7:19); autosomal recessive, affects 1 per 20,000; yellow-brown and radioopaque stones form at low urinary pH; crystals are flat hexagons in urine
● Ammonium acid urate: rare, but more common in Asia (Kaohsiung J Med Sci 2012;28:259)
● Stone granuloma: complication of ureteral stone fragmentation and instrumentation
● Xanthinuria (rare): autosomal recessive, due to deficient xanthine oxidase, causing excessive xanthine levels and stones in 1/3 with this disorder
● 48 year old man with nephrectomy for renal mass due to urolithiasis caused by 2,8-dihydroxyadenine crystals (Hum Pathol 1992;23:1081)
End of Kidney non-tumor > Miscellaneous > Urolithiasis (stones)
Ref Updated: 9/6/12
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