What are the signs and symptoms of nephrolithiasis (kidney stones)?

Signs and Symptoms of Nephrolithiasis (Kidney Stones)

The most common signs and symptoms of nephrolithiasis include acute flank pain (renal colic), hematuria, nausea, vomiting, and urinary urgency or frequency. 1 These clinical manifestations result from stone formation within the urinary tract and subsequent obstruction or irritation of the urinary system.

Cardinal Manifestations

Pain Characteristics

• Renal colic: Severe, sudden-onset flank pain that may radiate to the lower abdomen, groin, or genitals
• Pain intensity often fluctuates with ureteral peristalsis
• Pain may be colicky in nature (comes in waves)
• Location depends on stone position:
  • Upper ureter: Flank/costovertebral angle pain
  • Mid-ureter: Anterior abdominal pain
  • Lower ureter: Groin, scrotal, or labial pain

Urinary Symptoms

• Hematuria: Present in most cases, may be gross (visible) or microscopic 1
• Urinary urgency and frequency
• Dysuria (painful urination)
• Incomplete bladder emptying sensation

Associated Symptoms

• Nausea and vomiting (due to shared splanchnic innervation)
• Restlessness (patients often cannot find a comfortable position)
• Diaphoresis (sweating)
• Low-grade fever (higher temperatures suggest infection)

Clinical Presentation Variations

Asymptomatic Presentation

• Some stones may be clinically silent, especially if:
  • Located in the renal calyces without causing obstruction
  • Small in size (< 5mm)
  • Not causing significant obstruction

Complicated Presentations

• Infected obstructing stone: Presents with signs of urinary tract infection plus obstruction:

  • Fever, chills
  • Systemic inflammatory response
  • Potential for urosepsis (medical emergency) 2

• Complete obstruction: Can lead to:

  • Hydronephrosis
  • Renal impairment
  • Severe, unremitting pain

Diagnostic Clues

Physical Examination Findings

• Costovertebral angle tenderness
• Abdominal tenderness corresponding to the location of the stone
• Restlessness and inability to find comfortable position
• Tachycardia and diaphoresis may be present due to pain

Laboratory Findings

• Hematuria (microscopic or macroscopic) in approximately 85% of cases
• Crystalluria may be present on urinalysis
• Elevated white blood cell count if infection is present
• Abnormal renal function tests if significant obstruction exists

Imaging Findings

Noncontrast CT is the gold standard for diagnosis with sensitivity as high as 97% 1. Key findings include:

• Direct visualization of the calculus
• Secondary signs:
  • Hydronephrosis
  • Hydroureter
  • Perinephric or periureteral stranding
  • Tissue rim sign around a ureteral stone

Risk Factors to Consider

Several factors increase the risk of nephrolithiasis 1:

• Low fluid intake (most modifiable risk factor)
• Diet high in animal protein, sodium, and oxalate
• Family history of kidney stones
• Prior history of kidney stones (recurrence rate 35-50% within 5 years)
• Certain medical conditions (gout, inflammatory bowel disease, hyperparathyroidism)
• Medications (certain diuretics, calcium supplements, protease inhibitors)

Common Pitfalls in Diagnosis

1. Misdiagnosis as other conditions: Flank pain can be mistaken for musculoskeletal pain, pyelonephritis, or other abdominal pathologies 3

2. Overlooking non-stone causes of similar symptoms: Conditions like Page kidney, renal infarction, or papillary necrosis can present similarly 3

3. Failing to recognize an infected obstructing stone: This is a urologic emergency requiring prompt drainage and antibiotics 2

4. Assuming all hematuria with flank pain is due to stones: Other serious conditions like renal cell carcinoma can present similarly

5. Missing stones on ultrasound: Ultrasound has limited sensitivity (75% for renal stones, only 38% for ureteral stones) 1

Clinical Decision-Making Algorithm

1. Assess pain severity and vital signs:

   • Stable patient: Proceed with diagnostic workup
   • Unstable or septic patient: Urgent intervention required

2. Order appropriate imaging:

   • First-line: Non-contrast CT (highest sensitivity and specificity) 1
   • Alternative (pregnancy, children): Ultrasound of kidneys and bladder

3. Evaluate for complications:

   • Check for signs of infection (fever, elevated WBC)
   • Assess renal function
   • Evaluate degree of obstruction

4. Determine need for urgent intervention:

   • Infected obstructing stone
   • Complete obstruction with renal impairment
   • Intractable pain or vomiting
   • Solitary kidney with obstruction

Remember that while most cases of flank pain and hematuria represent nephrolithiasis, maintaining awareness of other potential diagnoses is crucial for appropriate management and to avoid missing serious alternative conditions.