What is the best pain management for a 62-year-old female with impaired renal function, history of frequent kidney stones, presenting with severe right flank pain, hematuria, and leukocyturia?

Pain Management for Urolithiasis in a Patient with Impaired Renal Function

For a 62-year-old female with impaired renal function (eGFR 34) presenting with severe right flank pain due to suspected kidney stones, intravenous hydromorphone at a reduced dose (25-50% of normal dose) is the most appropriate first-line analgesic in the emergency setting.

Assessment of Pain and Clinical Presentation

The patient presents with:

• Severe right flank pain (9/10 intensity)
• Large amount of blood and leukocytes in urine
• History of frequent urolithiasis
• Impaired renal function (eGFR 34)
• Afebrile status

This presentation is highly consistent with acute renal colic due to kidney stones, though other diagnoses should be considered.

Pain Management Algorithm

First-line Treatment:

1. Opioid Therapy

   • Hydromorphone IV at 25-50% of normal dose (e.g., 0.25-0.5 mg IV) 1
   • Titrate slowly while monitoring for respiratory depression, sedation, and hypotension
   • Safer alternative than morphine in renal impairment

2. Why NOT NSAIDs:

   • NSAIDs are typically first-line for renal colic 2, but are contraindicated in this patient due to:
     • Age >60 years
     • Significantly impaired renal function (eGFR 34)
     • Risk of worsening kidney function 2, 1

3. Why NOT morphine:

   • Morphine should be avoided in patients with renal disease due to accumulation of active metabolite morphine-6-glucuronide 2, 1
   • Can worsen adverse effects in patients with renal insufficiency

Alternative Options (if hydromorphone unavailable):

• Fentanyl IV (preferred alternative): 25-50 mcg IV 1

  • Minimal renal clearance and no active metabolites
  • Safer option in renal impairment

• Buprenorphine IV: Consider if hydromorphone and fentanyl unavailable 1

  • Mainly metabolized by the liver
  • No dose reduction necessary

Adjunctive Measures

• Hydration: Intravenous fluids to maintain adequate hydration unless contraindicated
• Antiemetics: Consider metoclopramide for opioid-related nausea/vomiting 1
• Urinary Strain: Collect urine for stone analysis if passed
• Imaging: Renal ultrasonography as first-line imaging 2
  • Low-dose non-contrast CT if diagnosis remains uncertain

Monitoring Requirements

• Vital signs: Frequent monitoring for hypotension, respiratory depression
• Pain assessment: Regular evaluation of pain control
• Renal function: Monitor for changes in renal parameters
• Watch for complications: Urinary obstruction, infection, worsening hematuria

Important Cautions

• Avoid NSAIDs including ketorolac: Despite ketorolac being effective for renal colic, it's contraindicated in this patient due to her age (>60 years) and impaired renal function 2, 3
• Avoid meperidine: Contraindicated in patients with impaired renal function due to risk of neurotoxicity 2
• Avoid high doses of opioids: Start low and titrate slowly due to risk of accumulation in renal impairment 1
• Consider infection: Though afebrile, monitor for signs of infection given the presence of leukocytes in urine

Follow-up Considerations

• Transition to oral analgesics once pain is controlled
• Consider medical expulsive therapy if appropriate based on stone size and location
• Arrange for comprehensive metabolic evaluation after acute episode resolves

Common Pitfalls to Avoid

1. Using NSAIDs in patients with impaired renal function
2. Administering standard doses of opioids in renal impairment
3. Failing to monitor for respiratory depression with opioid therapy
4. Overlooking potential urinary tract infection despite afebrile status
5. Delaying imaging if diagnosis is uncertain or pain is unresponsive to treatment

By following this algorithm, effective pain control can be achieved while minimizing risks in this patient with impaired renal function.