What is the initial management for a patient presenting with a kidney stone in a primary care setting, considering pain management, renal function assessment, and potential preventive measures?

Initial Management of Kidney Stones in Primary Care

Administer intramuscular diclofenac 75 mg immediately as first-line analgesia, with the goal of achieving pain relief within 30 minutes, and admit the patient to hospital if pain persists after 60 minutes. 1, 2

Immediate Pain Management (Within 30 Minutes)

First-Line Analgesia: NSAIDs

• Give intramuscular diclofenac 75 mg as the preferred first-line agent because it provides superior efficacy compared to opioids, reduces the need for additional analgesia, and has fewer side effects 1, 2, 3
• The intramuscular route is essential in primary care because oral and rectal administration are unreliable, and intravenous administration is impractical in the patient's home 1
• NSAIDs work by reducing prostaglandin synthesis, which decreases ureteral spasm and inflammation 2

When NSAIDs Are Contraindicated

• Use morphine sulfate combined with cyclizine (an antiemetic) given intramuscularly if the patient has: 1, 2
  • Renal impairment or renal failure 2
  • Cardiovascular disease 2
  • History of gastrointestinal bleeding 2
  • Pregnancy 2
  • Known allergy to NSAIDs or salicylates 1

Critical Assessment Before Treatment

Establish the Diagnosis

• Look for abrupt onset of severe unilateral flank pain radiating into the groin or genitals 1
• Examine the abdomen to exclude peritonitis and assess vital signs (pulse, blood pressure, temperature) to exclude shock and systemic infection 1

Red Flags Requiring Immediate Hospital Admission (Before Attempting Home Management)

• Age over 60 years (consider leaking abdominal aortic aneurysm) 1, 2
• Women with delayed menses (consider ectopic pregnancy) 1, 2
• Shock or signs of systemic infection/fever 1, 2
• Sepsis and/or anuria in an obstructed kidney (requires urgent decompression) 2, 3

Follow-Up Protocol After Initial Treatment

One-Hour Telephone Follow-Up

• Call the patient exactly one hour after administering analgesia to assess pain control 1, 2, 3
• If severe pain has not remitted within this hour, immediately admit the patient to hospital by telephone without requiring another in-person visit 1, 2
• Complete or acceptable pain control should be maintained for at least six hours 1, 2

Patient Instructions for Home Management

• Maintain high fluid intake 1
• Attempt to strain/sieve urine through a tea strainer or gauze to catch any identifiable stone for analysis 1
• Contact the doctor immediately if pain worsens or unexpected symptoms develop 1

Renal Function Assessment and Investigation

Fast-Track Imaging Protocol

• Arrange renal imaging (ultrasound or CT urography) within 7 days of symptom onset for all patients with suspected renal colic, whether managed at home or admitted 1
• Initiate this by transmitting a precoded fax to activate the pathway of care 1
• Ultrasound is the recommended first-line imaging modality in primary care and is preferred in pregnant patients 4

Urology Referral

• Schedule urology outpatient assessment within 7-14 days if imaging identifies a calculus requiring intervention 1
• Ensure the general practitioner receives copies of imaging reports before the urology appointment 1

Metabolic Testing (For Prevention)

• Recommend metabolic evaluation for high-risk patients including those with: 4
  • Family history of stones
  • Single kidney
  • Malabsorption or intestinal disease
  • Recurrent stone formation

Preventive Measures to Discuss

Immediate Dietary Counseling

• Increase fluid intake to achieve urine output of 2.0-2.5 L/day (requires drinking 2.5-3.0 L/day) 5
• Limit sodium intake to 2-3 g/day (equivalent to 3-5 g/day of sodium chloride) 5
• Maintain adequate dietary calcium at 1000-1200 mg/day (do not restrict calcium as this may worsen oxaluria and increase osteoporosis risk) 6, 5
• Limit animal protein to 0.8-1.0 g/kg body weight/day 5

Medical Expulsive Therapy

• Consider alpha-blockers for stones >5 mm in the distal ureter to facilitate passage 3
• This is first-line therapy if stones do not resolve with observation alone 4

Long-Term Prevention (Based on Stone Type)

• For calcium stones with hypocitraturia: potassium citrate 30-80 mEq/day in divided doses to increase urinary citrate and pH 7
• For hyperuricemia or uric acid stones: allopurinol 1, 6
• For hypercalciuria: thiazide diuretics 6, 5

Critical Pitfalls to Avoid

• Never delay analgesia while waiting for diagnostic tests 2
• Never use standard opioid dosing in patients with renal failure—start with lower doses and titrate carefully, and avoid morphine, codeine, or tramadol as first-line agents 2, 3
• Never discharge patients before ensuring adequate pain control for at least six hours 2
• Never miss signs of infection with obstruction, which requires urgent urological intervention 2
• Do not routinely restrict dietary calcium, as this may worsen stone formation and bone health 6, 5
• NSAIDs may worsen renal function in patients with low GFR, volume depletion, heart failure, or renal artery stenosis—use the lowest effective dose and monitor carefully 2