Kratom-Induced FSGS: Case Report Links Year of Heavy Use to Severe Kidney Failure

Why it matters

A new case report presented at the National Kidney Foundation Spring Clinical Meeting links one year of heavy kratom use to severe, biopsy-confirmed kidney failure — adding nephrology to the growing list of organ systems at risk from high-dose kratom.

The big picture

Kratom is widely marketed as a natural supplement, but heavy use — particularly at doses far exceeding typical consumption — has been associated with liver, cardiovascular, and now kidney damage. This case is notable because it was biopsy-proven and attributed to kratom in the absence of other secondary causes, giving it stronger clinical weight than prior anecdotal reports.

Key findings

• A 51-year-old man who consumed approximately 30 grams of kratom every 4 hours for one year developed acute kidney injury with nephrotic-range proteinuria
• Kidney biopsy revealed focal segmental glomerulosclerosis (FSGS) with global glomerulosclerosis in 22 of 44 glomeruli
• Serum creatinine reached 6.37 mg/dL and potassium hit 8.0 mmol/L, indicating severe kidney dysfunction
• All serologic and infectious workups were negative, pointing to kratom as the primary driver
• Researchers recommend clinicians routinely ask patients about herbal supplement use when evaluating unexplained kidney injury

What they say

"This case emphasizes the importance of routinely inquiring about herbal and over-the-counter supplement use when evaluating unexplained kidney injury, as early recognition may prevent irreversible kidney damage," wrote lead author Dr. Andre Crestani and colleagues from the University of Texas Health Science Center at San Antonio.

Bottom line

Heavy, prolonged kratom use can trigger severe kidney failure — a risk clinicians should screen for in patients with unexplained renal decline.