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Thematic Area: Nephrolithiasis

What is Nephrolithiasis (Kidney Stones)?

Nephrolithiasis, commonly known as kidney stones, is a condition characterized by the formation of solid mineral and salt crystals (stones) within the kidneys or the urinary tract. These stones can range in size from tiny grains to larger, more substantial structures. Kidney stones can cause significant pain and discomfort as they pass through the urinary system.

 

Nephrolithiasis – Urolithiasis

Nephrolithiasis refers to the presence of stones within the renal pelvis, while urolithiasis refers to stones in the kidney that are localized within the tubular lumen and lower urinary tract or primary bladder stones.
 

What causes  Kidney stones?

The exact cause of nephrolithiasis can vary, but it typically occurs due to an imbalance in the substances present in the urine, such as calcium, oxalate, uric acid, and cystine. When the concentration of these substances becomes too high, they can crystallize and form stones. Other factors that can contribute to kidney stone formation include:

  • Dehydration: Insufficient fluid intake can lead to concentrated urine, increasing the likelihood of stone formation.
  • Diet: Consuming a diet high in certain substances, such as oxalate (found in some fruits, vegetables, and nuts) or sodium, can increase the risk of stone formation.
  • Family history: A family history of kidney stones can predispose individuals to develop them.
  • Medical conditions: Certain medical conditions, such as hyperparathyroidism, gout, and urinary tract infections, can increase the risk of kidney stones.
  • Certain medications: Some medications can contribute to stone formation.

 

Nephrolithiasis Symptoms:

The symptoms of nephrolithiasis can vary depending on the size and location of the kidney stones. Small stones may pass through the urinary tract unnoticed, while larger stones can cause severe pain and other symptoms, including:

  • Intense, colicky pain in the back or side (flank pain)
  • Pain radiating to the lower abdomen and groin
  • Hematuria (blood in the urine)
  • Frequent urination
  • Painful urination
  • Cloudy or foul-smelling urine
  • Nausea and vomiting.

 

Diagnosis

Diagnosis of nephrolithiasis usually involves a combination of medical history, physical examination, and imaging tests, such as X-rays, ultrasound, or CT scans, to visualize the stones and determine their size and location.

 

Treatment of kidney stones:

Treatment of kidney stones depends on their size and location, as well as the severity of symptoms. Small stones may pass spontaneously with increased fluid intake and pain management. For larger stones or those causing severe symptoms, treatment options may include:

  • Extracorporeal shock wave lithotripsy (ESWL): Using shock waves to break the stones into smaller pieces for easier passage.
  • Ureteroscopy: Inserting a thin, flexible scope into the urinary tract to remove or break up the stones.
  • Percutaneous nephrolithotomy (PCNL): A surgical procedure to remove larger stones through a small incision in the back.
  • Medications: Some medications may be prescribed to help dissolve certain types of stones or prevent their formation.
  • Preventing nephrolithiasis involves maintaining proper hydration by drinking plenty of water throughout the day and making dietary adjustments, if necessary, especially if someone is prone to specific types of kidney stones.

  •  If someone has a history of kidney stones or experiences symptoms suggestive of nephrolithiasis, they should seek medical attention for appropriate evaluation and management.

Experts Recommendations:

EAU Guidelines on Urolithiasis  

Reference: Türk C, Petřík A, Sarica K, et al. Eur Urol. (2016). doi:10.1016/j.eururo.2015.07.041

Core Recommendations:    

  1. With fever or solitary kidney, and when diagnosis is doubtful, immediate imaging is indicated. Following initial US assessment, non contrast enhanced computed tomography should be used to confirm stone diagnosis in patients with acute flank pain.
  2. In pregnant women, ultrasound is the imaging method of choice.
  3. Always perform stone analysis in first-time formers using a valid procedure.
  4. In all paediatric patients, efforts should be made to complete a metabolic evaluation based on stone analysis.
  5. The dosage of alkalising medication must be modified by the patient according to urine pH, which is a direct consequence of such medication.
  6. Renal stones should be treated in the case of growth, formation of de novo obstruction, associated infection, and acute or chronic pain.
  7. Identification of biochemical risk factors and appropriate stone prevention is particularly indicated in patients with residual fragments or stones.
  8. For recurrence prevention, the aim should be to obtain a 24-h urine volume > 2.5 L, restricted intake of salt, and avoid excessive intake of animal protein.

Comments of Evaluators:    

  • Level of evidence and grade of recommendation given according to Oxford EBM Centre.
  • Only urologists involved. 

Medical management of kidney stones: AUA guideline

Reference: Pearle MS, Goldfarb DS, Assimos DG, et al. J Urol. (2014). doi: 10.1016/j.juro.2014.05.006

Core Recommendations:

  1. Clinicians should perform additional metabolic testing in high-risk or interested first-time stone formers and recurrent stone formers.
  2. Metabolic testing should consist of one or two 24-hour urine collections obtained on a random diet and analyzed at minimum for total volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium and creatinine.
  3. Clinicians should recommend to all stone formers a fluid intake that will achieve a urine volume of at least 2.5 liters daily
  4. Clinicians should counsel patients with calcium stones and relatively high urinary calcium to limit sodium intake and consume 1,000 - 1,200 mg per day of dietary calcium.
  5. Clinicians should offer thiazide diuretics to patients with high or relatively high urine calcium and recurrent calcium stones.
  6. Clinicians should offer potassium citrate therapy to patients with recurrent calcium stones and low or relatively low urinary citrate 
  7. Clinicians should offer thiazide diuretics and/or potassium citrate to patients with recurrent calcium stones in whom other metabolic abnormalities are absent or have been appropriately addressed and stone formation persists.
  8. Clinicians should offer potassium citrate to patients with uric acid and cystine stones to raise urinary pH to an optimal level.
  9. Clinicians should offer cystine-binding thiol drugs, such as alpha-mercaptopropionylglycine (tiopronin), to patients with cystine stones who are unresponsive to dietary modifications and urinary alkalinization, or have large recurrent stone burdens.
  10. Clinicians should obtain periodic blood testing to assess for adverse effects in patients on pharmacological therapy.        

Comments by Evaluators:

  • No specific comments 

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