Crystalluria Flashcards
Risk factors for drug crystallization:
supersaturation of drug level in urine
volume depletion (low urine flow)
urine pH
reduced levels of inhibitors of crystallization
Crystalluria
Most drug-crystalluria-induced acute kidney injury (AKI) resolves with drug withdrawal and supportive therapy
Sulfadiazine (used to treat toxoplasmosis):
Risks: high dose > 4 to 6 g/d, urine pH < 5.5, volume depletion
Sulfadiazine (used to treat toxoplasmosis):
Crystals are strongly birefringent as “shocks of wheat” or “bow-tie” with an amber color and radial striation.
Sulfadiazine (used to treat toxoplasmosis):
Treatment: volume repletion, urine alkalinization with sodium bicarbonate to pH > 7.15
Ciprofloxacin:
Risks: alkaline urine (pH > 7.0), elderly patients, volume depletion
Ciprofloxacin:
Typically crystallizes in high urine pH > 7.3, but may occur in acidic pH
Ciprofloxacin:
Crystals may take forms as needles, stars, fan shaped; all with lamellar structures and are strongly birefringent under polarized light.
Ciprofloxacin:
Preventive measures: volume repletion, avoid concurrent use of alkalinizing agents, use with caution in patients > 65 to 70.
Acyclovir:
Risks: rapid intravenous bolus (500 mg/m2) for herpes simplex virus–associated encephalitis, volume depletion.
Acyclovir:
Crystals are birefringent and needle shaped
Acyclovir:
Preventive measures: use low dose, or slow infusion with normal saline support. Acyclovir is dialyzable.
Indinavir (HIV protease inhibitor):
Crystallizes at physiologic pH 5.5 to 7.0; soluble at pH of ≤3.5.
Indinavir (HIV protease inhibitor):
Crystals are pleomorphic and may range from plate-like rectangles, fan shaped, to start burst shaped.
Indinavir (HIV protease inhibitor):
Associated with tubular obstruction, chronic tubulointerstitial nephritis (CTIN)
Indinavir (HIV protease inhibitor):
Treatment: volume intake of at least 2 to 3 L/d is suggested while on indinavir; dose adjustment in liver disease; avoid concurrent use of trimethoprim–sulfamethoxazole as it can increase indinavir blood levels. Urine acidification difficult to achieve and not recommended.
Methotrexate:
Risks: low urine pH, low volume
Methotrexate:
May cause both tubular obstruction and direct tubular toxicity
Methotrexate:
Treatment: urine alkalinization to pH > 6.0, volume repletion, leucovorin rescue.
Triamterene:
Risks: urine pH < 5.5
Triamterene:
Crystals are spherical shaped, brown in color, appear as maltese crosses under polarized light.
Triamterene:
Preventive: use low dose, adequate volume intake, avoid concurrent nonsteroidal anti-inflammatory drugs (NSAIDS) use.
Triamterene:
Treatment: volume repletion, urinary alkalinization
Orlistat (inhibitor of gastric and pancreatic lipase, induces fat malabsorption):
Associated with calcium oxalate deposition within renal tubules and interstitium. Mechanism for calcium oxalate stone formation is thought to be similar to that seen in patients with inflammatory bowel disease.
Orlistat (inhibitor of gastric and pancreatic lipase, induces fat malabsorption):
Risks: underlying kidney disease, volume depletion
Orlistat (inhibitor of gastric and pancreatic lipase, induces fat malabsorption):
Preventive: avoid use in patients with underlying kidney disease, volume repletion
Ampicillin:
Needle Shaped
Oral sodium phosphate solution used as bowel preparation for colonoscopy:
Calcium phosphate precipitations in renal tubular cells as well as tubular lumen
Oral sodium phosphate solution used as bowel preparation for colonoscopy:
Risks: underlying kidney disease, females, and possibly hypertension (HTN) with concurrent use of angiotensin-converting enzyme inhibitor (ACEI) or angiotensin-receptor blocker (ARB)
Oral sodium phosphate solution used as bowel preparation for colonoscopy:
Preventive measures: volume repletion, appropriate dosing, avoid concurrent use with ACEI, ARB, diuretics, and/or NSAIDS; Exercise caution with use in older patients.
Vitamin C
(converts to oxalate, calcium oxalate stones)
Other drug crystalluria:
foscarnet, pseudoephedrine
Natural sources:
star fruit (oxalate), rhubarb leaves (oxalate), cranberry juice (oxalate), ma huang (ephedra), djenkol beans (needle like)
