Is spinning the urine a special request or a routine part of urinalysis for a patient with a history of cocaine use and suspected Thrombotic Microangiopathy (TMA) with potential kidney injury?

Urine Spinning for Microscopy in Cocaine-Associated TMA

Spinning urine for microscopic examination is a routine part of standard urinalysis, not a special request, and is particularly important in patients with suspected thrombotic microangiopathy (TMA) and kidney injury to identify red blood cell casts, dysmorphic RBCs, and other cellular elements that guide diagnosis and management. 1, 2

Standard Urinalysis Components

• Urine centrifugation (spinning) is performed routinely as part of complete urinalysis to examine the sediment microscopically for cells, casts, crystals, and other formed elements 1
• The microscopic examination of spun urine sediment is essential for detecting red blood cell casts and dysmorphic RBCs, which indicate glomerular injury in TMA 2, 3
• This is distinct from urine toxicology screening for cocaine metabolites (benzoylecgonine), which requires a separate qualitative immunoassay 4

Critical Findings in Cocaine-Associated TMA

• In cocaine-induced TMA with kidney injury, urine microscopy typically reveals hematuria, proteinuria, and may show red blood cell casts indicating glomerular involvement 1, 2
• Cocaine can cause multiple patterns of kidney injury including thrombotic microangiopathy, acute tubular necrosis, glomerular ischemia, and fibrinoid necrosis of arterioles 5, 2
• The presence of schistocytes on peripheral blood smear combined with thrombocytopenia and hemolytic anemia supports TMA diagnosis, while urine sediment helps localize renal involvement 2, 3

Cocaine Detection vs. Urinalysis

• Cocaine metabolite testing (benzoylecgonine) should be ordered separately when substance abuse is suspected, especially in younger patients with few cardiac risk factors 4
• The American Heart Association recommends that establishing cocaine use should depend primarily on self-reporting, with urine toxicology reserved for specific cases when the patient cannot communicate or when substance abuse is suspected as a contributor 4
• Benzoylecgonine can be detected in urine for 24-48 hours after use (up to 22 days in chronic heavy users), with a standard cutoff of 300 ng/mL 4

Common Pitfall

Do not confuse routine urinalysis with microscopy (which includes spinning) with the separate urine drug screen for cocaine metabolites—both may be needed but serve different diagnostic purposes. The former evaluates kidney injury patterns while the latter confirms recent cocaine exposure. 4, 1