I have flank (kidney‑type) pain and use ketamine; what is the appropriate initial management and work‑up?

Ketamine-Related Kidney Pain: Initial Management and Work-Up

If you have flank pain and use ketamine recreationally, immediately stop all ketamine use and undergo urgent imaging with CT abdomen/pelvis without IV contrast to rule out hydronephrosis and ureteral obstruction, as ketamine-induced uropathy can cause irreversible kidney damage even after cessation. 1, 2

Immediate Assessment and Diagnostic Work-Up

Initial Clinical Evaluation

• Document ketamine use history: quantity (grams per day), duration of use, frequency, and time since last use 2, 3
• Assess for urologic symptoms: dysuria, urinary frequency, urgency, burning micturition, hematuria, and reduced bladder capacity 2, 4
• Check renal function: serum creatinine, estimated GFR, and gamma-glutamyl transferase (GGT), as elevated GGT correlates with hydronephrosis risk 3

Imaging Protocol

CT abdomen and pelvis without IV contrast is the gold standard initial imaging study for evaluating flank pain with suspected stone disease or obstruction 5

• This modality identifies hydronephrosis, ureteral strictures, and bladder wall thickening characteristic of ketamine-induced uropathy 2, 3
• Ultrasound kidneys and bladder retroperitoneal is an acceptable alternative if CT is contraindicated, though less sensitive for ureteral pathology 5
• Avoid contrast-enhanced CT initially unless non-contrast CT is inconclusive, as contrast obscures stones in the renal collecting system 5

Understanding Ketamine-Induced Uropathy

Pathophysiology

Ketamine metabolites in urine cause direct toxic damage to the bladder epithelium, leading to inflammatory cell infiltration (mast cells, eosinophils), urothelial denudation, vascular changes, oxidative stress, and progressive fibrosis 4, 6

This inflammatory cascade extends from the bladder to the ureters and kidneys, causing:

• Ulcerative cystitis with easily bleeding mucosa 4
• Bladder wall thickening and contracture 4, 6
• Ureteral strictures and obstruction 2, 6
• Hydronephrosis and potential renal failure 2, 6

Risk Stratification

Hydronephrosis occurs in approximately 25% of ketamine uropathy patients and represents severe disease requiring urgent intervention 3

High-risk features include:

• Daily ketamine use ≥5 grams 2
• Duration of use >2 years 2
• Elevated serum GGT 3
• Bilateral flank pain 2

Management Algorithm

Step 1: Immediate Ketamine Cessation (Mandatory for All Patients)

Complete and permanent cessation of ketamine is the cornerstone of treatment and must be initiated immediately 4, 3, 6

• Early cessation in mild cases can lead to symptom resolution 4
• Continued use causes irreversible bladder contracture and renal damage 2, 4
• Provide motivational interviewing, psychological support, and addiction counseling 1

Critical pitfall: Some patients attempt to manage urinary pain by increasing ketamine use, creating a vicious cycle of worsening uropathy 1

Step 2: Urgent Urologic Intervention (If Hydronephrosis Present)

If imaging reveals hydronephrosis or ureteral obstruction:

• Immediate urology consultation for possible nephrostomy tube or ureteral stent placement 2, 3
• Six of 20 patients (30%) with hydronephrosis in one series required nephrostomy insertion 3
• Bilateral ureteral stents may be needed and can require long-term maintenance even after ketamine cessation 2

Step 3: Medical Management (Early Disease Without Obstruction)

For patients with bladder symptoms but no upper tract involvement:

Anticholinergic medications for overactive bladder symptoms 3

Intravesical therapies (administered by urology):

• Hyaluronic acid instillation to restore urothelial barrier 4
• Botulinum toxin type A injection for refractory bladder pain 4

These interventions are most effective in early disease with ketamine abstinence 4

Step 4: Surgical Management (Irreversible Disease)

For patients with contracted bladder and intractable pain despite conservative measures:

• Augmentation enterocystoplasty is the definitive surgical option to increase bladder capacity and relieve pain 4, 6
• This represents end-stage disease and is required when pathological changes are irreversible 4
• One patient in a recent UK series required bladder augmentation 3

Prognosis and Follow-Up

Expected Outcomes

Cessation of ketamine does not guarantee symptom resolution, particularly in advanced disease 2

• Early cessation (within months of symptom onset) offers the best chance of recovery 4
• Patients with chronic use (>2 years) often have permanent damage requiring ongoing intervention 2
• Symptoms typically relapse if ketamine use resumes after stopping 6

Long-Term Monitoring

• Adherence to follow-up is notoriously poor in this population, with many patients lost to follow-up 3
• Establish multidisciplinary care involving urology, nephrology, addiction medicine, and mental health 3
• Serial renal function monitoring (creatinine, GFR) every 3-6 months 2
• Repeat imaging if symptoms worsen or new flank pain develops 3

Key Clinical Pearls

Maintain high suspicion for ketamine uropathy in young patients (average age 26-27 years) presenting with unexplained hydronephrosis, cystitis-like symptoms, or renal dysfunction 2, 3

The male-to-female ratio is approximately 3:1 3

Do not assume symptoms will resolve with cessation alone—some patients require permanent ureteral stents or surgical reconstruction despite years of abstinence 2

The incidence is rising in parallel with increasing recreational ketamine use, particularly in certain geographic regions 3