Amoxicillin-Induced Crystalline Nephropathy Presenting as Ureteral Obstruction

The Crystalline Nephropathies

“…Amoxicillin is a widely employed antimicrobial agent. While generally safe, it has been associated with AKI from AIN, stones and crystalline nephropathy (48)(49)(50)(51)(52)(53). Following glomerular filtration and organic anion transporter-driven tubular secretion of amoxicillin, intra-renal crystal deposition likely occurs due to concentration-dependent oversaturation of amoxicillin and urinary crystallization in an acidic urine pH (48)(49)(50)(51)(52)(53).…”

“…The crystals are needle or rod shapes that can form "bunches" or "sheaves". Risk factors for crystalline nephropathy include high amoxicillin doses, acid urine pH, and volume depletion with low urine flow rates (48)(49)(50)(51)(52)(53). However, like sulfadiazine and sulfamethoxazole, no histologic evidence of intra-renal deposits of amoxicillin crystals have been published despite the association of amoxicillin with AKI and concurrent crystalluria (48)(49)(50)(51)(52)(53).…”

“…Prevention and treatment of suspected crystalline nephropathy hinges upon medication discontinuation and volume repletion (48)(49)(50)(51)(52)(53). In patients with AKI, it may be useful to undertake kidney biopsy to differentiate AIN from crystalline nephropathy.…”

“…With AIN, corticosteroids might be beneficial and amoxicillin would be otherwise contraindicated for future use. In patients with urine pH <6.0, urine alkalinization may also be beneficial to prevent urinary crystal precipitation within tubules (48)(49)(50)(51)(52)(53).…”

“… 48 , 49 , 50 , 51 , 52 , 53 After glomerular filtration and organic anion transporter-driven tubular secretion of amoxicillin, intrarenal crystal deposition likely occurs owing to concentration-dependent oversaturation of amoxicillin and urinary crystallization in an acidic urine pH. 48 , 49 , 50 , 51 , 52 , 53 …”