Renal Calculi (Kidney Stone)

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1- Introduction

2- Pathophysiology

3- Symptoms

4- Treatment


Renal calculi, commonly known as kidney stones, are solid crystals that form in the kidneys when substances like calcium, oxalate, and uric acid become concentrated in the urine. These stones can vary in size, from tiny grains to large masses, and may cause severe pain as they move through the urinary tract. Treatment options range from pain management and hydration to medical interventions or procedures to break up or remove larger stones. Preventive measures often include dietary changes and increased fluid intake to reduce the risk of recurrence.

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The pathophysiology of renal calculi, or kidney stones, revolves around the formation of solid crystalline structures within the kidneys and urinary tract. These stones develop when substances like calcium, oxalate, uric acid, and others become concentrated in the urine, exceeding its capacity to dissolve them. Factors such as dehydration, dietary habits rich in oxalates or salts, and genetic predispositions can contribute to the supersaturation of urine, leading to the crystallization of these substances. Imbalances in urinary inhibitors and promoters further influence stone formation, with deficiencies in substances like citrate impairing the urine’s ability to prevent crystal aggregation. Additionally, the urinary pH plays a critical role; acidic conditions can promote uric acid stones, while alkaline environments favor the formation of calcium phosphate stones. Conditions that hinder urine flow or cause stasis, such as anatomical abnormalities or urinary tract obstructions, also increase the likelihood of stone development.

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  • Severe Pain: Often described as one of the most intense pains experienced, typically located in the flank or lower abdomen. The pain can radiate to the groin and may come in waves as the stone moves through the urinary tract (renal colic).

  • Hematuria: Blood in the urine, which can vary from microscopic amounts to visible red or brown discoloration.

  • Urinary Symptoms: Increased urinary urgency, frequency, or discomfort during urination.

  • Nausea and Vomiting: Especially if the pain is severe or persistent.

  • Difficulty Urinating: Sometimes accompanied by pain or a sensation of incomplete emptying.

  • Fever and Chills: In cases where there is associated infection or obstruction causing urinary stasis.

  • Cloudy or Foul-Smelling Urine: Due to the presence of infection or urinary stasis.

  • Renal Colic: This is a characteristic episodic pain that occurs as the kidney stone moves within the urinary tract, causing intermittent obstruction and subsequent release.


  • Pain Management:

    • Over-the-Counter Pain Relievers: Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or acetaminophen to alleviate pain and discomfort.
    • Prescription Pain Medications: Stronger medications may be prescribed for severe pain that is not adequately controlled with NSAIDs.
  • Hydration:

    • Drinking plenty of fluids, typically water, to increase urine volume and help flush out the stone from the urinary tract. Increased fluid intake is crucial to prevent dehydration and reduce the concentration of minerals that form stones.
  • Medical Therapy:

    • Alpha Blockers: Medications like tamsulosin may be prescribed to relax the muscles in the ureter, helping to facilitate the passage of the stone.
    • Medications to Alkalize or Acidify Urine: Depending on the type of stone (e.g., uric acid stones), medications may be used to adjust urinary pH and facilitate stone dissolution or passage.
  • Extracorporeal Shock Wave Lithotripsy (ESWL):

    • This non-invasive procedure uses shock waves to break larger stones into smaller pieces that can pass more easily through the urinary tract.
  • Ureteroscopy with Laser Lithotripsy:

    • A minimally invasive procedure where a thin scope is inserted through the urethra and bladder into the ureter to directly visualize and fragment the stone using laser energy.
  • Percutaneous Nephrolithotomy (PCNL):

    • Surgical intervention typically reserved for larger or complex stones. A small incision is made in the back to access and remove the stone using specialized instruments.
  • Surgical Removal (Open Surgery):

    • Rarely needed today due to less invasive techniques, open surgery may be considered for very large stones or cases where other methods have not been successful.
  • Preventive Measures:

    • Once the stone is treated or passed, preventive measures focus on dietary modifications (e.g., reducing salt and oxalate intake), increasing fluid intake, and sometimes medications to prevent stone recurrence.
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