Nephrolithiasis - Kidney Stones – Quick Consult
Last Updated / Reviewed: 4/5/2021

Definition
Key History
Key Physical Exam
Risk Factors
Differential Diagnosis
Diagnostic Testing
Treatment
Clinical Risk and Safety Pearls
Complications 

Definition

Stones are broadly classified into calcareous (calcium-containing and radiopaque) and noncalcareous types. The majority (over 90%) of nephrolithiasis in adults involve calcium-containing stones.

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Key History

  • Acute onset of abdominal or flank pain
  • Pain is usually colicky
  • May radiate from flank to the groin, or to the scrotum/labia
  • May have gross hematuria
  • Unable to get comfortable, difficulty sitting still due to the pain
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Key Physical Exam

  • May have mild to no abdominal tenderness
  • May have CVA tenderness
  • May be diaphoretic and pale related to pain
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Risk Factors

  • Chronic diseases: Inflammatory bowel, gout
  • Enhanced enteric oxalate absorption (e.g., gastric bypass procedures, bariatric surgery, short bowel syndrome)
  • Family history of stones
  • Grapefruit juice consumption
  • Marathon runners and those with decreased fluid intake
  • Medications: HIV protease inhibitors (indinavir), diuretics
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Differential Diagnosis

Gastrointestinal Genitourinary Gynecological
  • Dysmenorrhea
  • Ectopic pregnancy
  • Endometriosis
  • Menorrhagia
  • Ovarian torsion
  • PID
  • Ruptured cyst (Mittelschmerz)
  • Tubal ovarian abscess
  • Twisted ovarian cyst
Cardiovascular Other
  • Diabetes ketoacidosis
  • Hemolytic uremic syndromes
  • Herpes zoster
  • Henoch-Schoenlein purpura
  • Pneumonia
  • Sickle cell crisis
  • Streptococcal pharyngitis
  • Pneumothorax

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Diagnostic Testing

Text / literature information and recommendations include:
  1. Urinalysis: Hematuria (may not be present 15%), evaluate for crystals
  2. Urine culture if indicated by suspicion of infection
  3. Blood tests:
    • CMP for serum electrolytes, blood urea nitrogen (BUN), creatinine, calcium, and phosphate levels and uric acid level
    • Controversial whether needed to routinely evaluate BUN and creatinine for signs of renal insufficiency
  4. CT of the abdomen and pelvis without contrast performed using local radiation dose scanning technology is the preferred exam for most adults. This exam is available at most sites. If low radiation dose CT technology is not available, standard dose, noncontrast CT of the abdomen and pelvis or ultrasound of the kidneys and bladder are the two second-line alternatives.
  5. Intravenous pyelogram - it is not sensitive to small stones, and the use of iodine-containing contrast media may induce an allergic or anaphylactic reaction. It may also cause deterioration of renal function in patients with pre-existing renal damage.
  6. Renal ultrasonography is useful if patient with suspected stone disease is pregnant or is a child – decrease radiation exposure from CT scan. The color Doppler methods are the most accurate. Limited to evaluation in kidneys, renal pelvis, and proximal ureters
  7. Plain abdominal X-ray (KUB film) may be helpful in following the progress of an already-diagnosed, relatively large radiopaque stone. Not used frequently with availability of CT scanning as it has low sensitivity and low specificity for identifying stones.
  8. Calculus analysis of any stones or fragments collected. May help urologist or internist with treatment to decrease subsequent stone formation
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Treatment

Common text / literature recommendations include:
  1. Medications for pain control (e.g. opiate and/or NSAIDs)
  2. Obtain appropriate imaging to diagnose the presence of a stone and to rule out obstruction and hydronephrosis.
  3. If there is urinary tract infection with a kidney stone then IV antibiotics and admission should be performed.
  4. For smaller stones (e.g. <10mm), the use of medical therapies to promote stone passage may be of benefit. Agents used include alpha blockers (e.g. tamsulosin) and calcium channel blockers (e.g. nifedipine), sometimes in combination with a corticosteroid (e.g. prednisone).
  5. Urologic referral should be considered for patients with:
    1. Fever or UTI and any evidence of obstruction
    2. Pregnancy
    3. Prior history of recurrent calculi
    4. History of renal failure or single kidney
    5. Pain refractory to medical management
    6. Inability to tolerate oral liquids due to refractory nausea and vomiting
  6. Nephrology referral in presence of renal insufficiency (elevated serum creatinine and/or oliguria)
  7. Spontaneous passage is highly dependent upon stone size (90% of stones <5mm pass spontaneously compared with 10% of stones >1cm)
  8. Surgical interventions include extracorporeal shockwave lithotripsy, ureteroscopic extraction, percutaneous nephrolithotomy, and open pyelolithotomy.
  9. Secondary prevention methods include adequate hydration practice, medications indicated as a result of a metabolic workup, and the use of dietary modifications such as a low-salt and/or protein diet.
  10. Patients with single kidney and stones should be admitted or have close urologic follow up.
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Clinical Risk and Safety Pearls

  • Patients on chemotherapy for malignancy are at increased risk for developing uric acid stones.
  • Family history of stones may help suggest the diagnosis.
  • Decreased fluid intake and increased fluid losses (summer time, outdoor activity). Coffee (decaffeinated or regular) and wine drinkers have lower rates of stone formation.
  • Evaluation for the underlying cause of calculus formation may be performed as an outpatient; this may include consultations with a urologist and/or nephrologist, and includes a stone analysis.
  • If the patient has fever, consider stone complicated by infection, an indication for admission.
  • A urinary tract infection with a kidney stone together requires IV antibiotics and admission.
  • There is no evidence that forced diuresis enhances the passing of a stone, but high fluid intake, by diluting the urine, may ameliorate the prevalence of stone recurrence or enlargement.
  • CT scan or ultrasound should be performed to determine the diagnosis. While scanning it is useful to rule out abdominal aortic aneurysm and other acute causes of pain.
  • Pain may actually radiate into the genitalia or present in an atypical fashion with isolated testicular pain.
  • A passed stone can present without any identifiable stone on X-ray but with hydroureter and hydronephrosis.
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Complications

  • May lead to persistent renal obstruction, decreased glomerular filtration rate.
  • Over years, Staghorn calculi can lead to renal failure if they are present bilaterally.
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  1. Coe FL, Evan A, Worcester E: Kidney stone disease. J Clin Invest 2005; 115:2598-2608.
  2. Evan AP, Worcester EM, Coe FL, et al. Mechanisms of human kidney stone formation. Urolithiasis. 2015; 43 Suppl 1:19.
  3. Fulgham PF, Assimos DG, Pearle MS, Preminger GM. Clinical effectiveness protocols for imaging in the management of ureteral calculous disease: AUA technology assessment. J Urol. 2013; 189:1203.
  4. Fwu CW, Eggers PW, Kimmel PL, et al. Emergency department visits, use of imaging, and drugs for urolithiasis have increased in the United States. Kidney Int. 2013; 83:479.
  5. Lotan, Y, Cadeddu, JA, Roerhborn, CG, et al. Cost-effectiveness of medical management strategies for nephrolithiasis. J Urol 2004; 172:2275.
  6. Parmar, MS. Kidney Stones. BMJ 2004; 328:1420.
  7. Pearle, MS, Calhoun, EA, Curhan, GC. Urologic diseases in America project: urolithiasis. J Urol 2005; 173:848.
  8. Smith-Bindman R, Aubin C, Bailitz J, et al. Ultrasonography versus computed tomography for suspected nephrolithiasis. N Engl J Med. 2014; 371:1100.
  9. Teichman JM. Clinical practice. Acute renal colic from ureteral calculus. N Engl J Med. 2004; 350:684.

This is intended solely as reference material and is not a recommendation for any specific patient. The practitioner must rely upon his or her own professional judgment and medical decision-making to determine whether it is relevant in a particular case. Materials are derived from medical and nursing texts, medical literature and national guidelines and should not be considered complete or authoritative. Users must rely on specific patient presentation, experience and judgment when utilizing any of the information contained herein relative to an actual patient.

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