SUMMARY:

Nephrolithiasis, or kidney stones, is a common condition which affects up to 8.8% of the U.S. population. The incidence has been increasing over time, especially in the “stone belt” located in the Southeastern and South-Central United States.  It is most often characterized by colicky flank pain.  Calculi have various compositions including calcium oxalate, uric acid, struvite, calcium phosphate and, cystine.    

Symptoms

• Flank pain
• Pain radiating to groin
• Nausea
• Vomiting
• Urinary urgency
• Abdominal pain
• Urinary frequency
• Dysuria
• Hematuria

Risk Factors

• Urinary obstruction
• Hypertension
• Gout
• Obesity
• Diabetes
• Dietary
  • Excessive intake: Protein | Carbohydrates | Sodium
  • Low fiber | High oxalate | Carbonated drinks with phosphoric acid
  • Poor dietary fluid intake
• Urine composition
  • pH, Hyperuricosuria | Hypomagnesuria | Hypercalciuria | Xanthinuria Hypocitraturia
• Recurrent UTI with urease producing organisms
• Medications
  • Topiramate Triamterene | Furosemide | Acetazolamide
  • Vitamin C | Vitamin D

Differential Diagnosis

GI

• Intestinal obstruction
  • Abdominal pain | Unable to pass flatus or stool | Nausea and vomiting
• Mesenteric ischemia
  • Acute severe abdominal pain | Nausea | Vomiting | Pain after eating
• Cholecystitis
  • RUQ pain | Nausea and vomiting
• Appendicitis
  • RLQ pain | Fever | Nausea and vomiting

GU

• Renal or ureteral stone
  • Flank pain | Nausea and Vomiting | Dysuria
• UTI
  • Suprapubic pain | Urinary frequency | Uinary urgency
• Prostatitis
  • Dysuria | Difficulty urinating | Genital or perineal pain | Fever
• Pyelonephritis
  • Fever | Chills | Flank pain | Dysuria

Cardiovascular

• Abdominal aortic aneurysm
  • Abdominal pain | Pulsatile mass | Hypotension

Pulmonary

• Pneumonia
  • Fever | Cough | Dyspnea
• Rib fracture
  • Pain with inspiration |  History of trauma

Other

• Ectopic pregnancy
  • Vaginal bleeding | Pelvic pain | Nausea
• Ovarian cyst or torsion
  • Pelvic pain | Bleeding | Nausea and vomiting
• Herpes Zoster
  • Radicular pain | Vesicular rash
• Sciatica
  • Low back pain | Radicular pain down leg | Paresthesia

Diagnostic Evaluation    

• Urinalysis
• Urine Culture
• Non-contrast CT scan of the abdomen and pelvis (gold standard)
• Intravenous pyelogram (previous gold standard)
• Ultrasound of the kidneys can be used effectively and avoids radiation in adults under 50
• KUB – plain abdominal radiograph
• CBC
• Creatinine

Treatment

• The most important key to managing patient with nephrolithiasis is determining whether urgent intervention is needed

Pain Control

• NSAID
  • More effective pain relief with fewer side effects
  • May be contra-indicated in renal impairment
• Narcotic
  • Used if NSAID is ineffective

Expectant Management

• Stone size and location are important
• Stones < 5 mm in diameter are likely to pass spontaneously
• Likelihood of stones passing spontaneously decreases as stone size increases
• Can facilitate passage within the distal ureter with medical expulsive therapy
  • Alpha blockers
    • Tamsulosin: 0.4 mg per day
    • Doxazosin: 4 mg per day
  • Calcium channel blockers
    • Nifedipine: less effective
• Repeat imaging after 2 weeks to assess stone position and look for hydronephrosis
• Referral to urology if no improvement after 2 to 4 weeks

Urgent Intervention

• Urgent intervention required for the following
  • Obstructed upper urinary tract with infection/sepsis
  • Pain refractory to analgesics
  • Anuria
  • Impending renal deterioration (abnormal creatinine)
  • Intractable nausea and vomiting
  • Solitary kidney
  • Hemodynamic instability
  • Patient preference
• Surgical management
  • Ureteroscopy
  • Extracorporeal shockwave lithotripsy
  • Percutaneous nephrolithotomy
  • Patient with signs of obstruction and infection may require ureteral stent

Complications

• Abscess formation
• Urosepsis
• Ureteral injury, scarring, stenosis
• Urinary fistula
• Renal function loss

Follow-up and Prevention

• Stone composition analysis
• 24-hour urinalysis
  • Total volume | Calcium | Oxalate | Sodium | Uric acid | Citrate | Creatinine | Magnesium | Phosphate | Cystine.
• Serum studies depend upon stone composition and clinical picture
  • Calcium | Phosphorous | Uric acid | Creatinine
• Lifestyle modification
  • Increase oral fluid intake to generate 2.5 L of urine in 24 hours
  • Balanced diet high in fiber and vegetables and limited sodium and animal protein
• Medications to be used with corresponding kidney composition 
  • Thiazide diuretics: Calcium stones
  • Allopurinol: Calcium stones | Uric acid stones
  • Citrate supplementation: Calcium stones | Uric acid stones | Cystine stones
• Repeat a 24-hour urine within 6 months of dietary changes or starting treatment with medications to assess response to therapy

Primary Sources – Learn More

Kidney Stones: Treatment and Prevention – American Family Physician (aafp.org)

AUA: Medical Management of Kidney Stones

AUA/Endourology: Surgical Management of Kidney Stones

Clinical Effectiveness Protocols for Imaging in The Management of Ureteral Calculous Disease: AUA Technology Assessment – American Urological Association (auanet.org)