What is the diagnosis for a patient presenting with significant hematuria, leukocyturia, proteinuria, and lower back pain?

Diagnosis: Acute Pyelonephritis or Urinary Tract Infection with Upper Tract Involvement

The combination of significant hematuria (blood +3), leukocyturia (leukocytes +3), proteinuria (protein +1), and lower back pain strongly suggests acute pyelonephritis or complicated urinary tract infection with possible upper tract involvement. 1

Clinical Reasoning

The urinalysis findings point toward an infectious or inflammatory process:

• Leukocyturia (+3) indicates active inflammation or infection within the urinary tract 1, 2
• Hematuria (+3) combined with leukocyturia is characteristic of urinary tract infection, particularly when involving the upper tracts 1, 3
• Lower back pain significantly increases the probability of pyelonephritis when combined with urinary symptoms (likelihood ratio 1.6) 3
• Proteinuria (+1) can occur with urinary tract infections due to inflammatory changes 1
• Acidic pH (6.5) is consistent with infection, though not diagnostic 1

Immediate Diagnostic Steps

Obtain urine culture before initiating antibiotics to identify the causative organism and guide antibiotic therapy 1, 4. This is critical for appropriate management.

Assess for systemic signs of infection:

• Fever (present in 67-98% of pyelonephritis cases) 1
• Costovertebral angle tenderness (likelihood ratio 1.7 for UTI) 3
• Signs of sepsis or hemodynamic instability 1

Rule out urinary tract obstruction or structural abnormalities with renal ultrasound if:

• Patient has recurrent infections 1
• Fever persists beyond 72 hours of appropriate antibiotics 1
• There is concern for abscess or obstruction 1

Important Differential Considerations

While infection is most likely, do not ignore other causes of this presentation:

• Urolithiasis can present with hematuria, flank pain, and secondary infection 1
• Iatrogenic urinary tract injury if recent instrumentation or surgery (presents with fever, hematuria, flank pain, and leukocytosis) 1
• Glomerulonephritis if proteinuria worsens or red blood cell casts are present 1

Examine urine sediment microscopically to look for:

• White blood cell casts (suggest pyelonephritis) 1
• Red blood cell casts or dysmorphic RBCs (suggest glomerular disease) 1, 5
• Bacteria on microscopy (supports infection) 3

Critical Pitfalls to Avoid

Do not dismiss this as simple cystitis. The presence of back pain with significant hematuria and leukocyturia suggests upper tract involvement requiring more aggressive treatment 1, 3.

Do not delay imaging if the patient has:

• Persistent fever after 72 hours of antibiotics 1
• Worsening renal function 1
• History of urologic abnormalities or recurrent infections 1

Do not treat empirically without obtaining urine culture first, as this population may harbor resistant organisms and antibiotic stewardship is critical 1.

When to Refer for Specialist Evaluation

Immediate urology consultation is warranted if:

• Suspected urinary tract obstruction or stone disease 1
• Recent instrumentation with concern for iatrogenic injury 1
• Persistent gross hematuria despite treatment 1, 4

Nephrology consultation should be considered if:

• Proteinuria persists or worsens after infection treatment 1
• Red blood cell casts or dysmorphic RBCs are present 1
• Renal function deteriorates 1