Kidney Stones: Comprehensive Study Notes

Calcul Phosphate

CalciumIVA

Calcul Oxalate Calcium Dihydrate lla

Calcul Oxalate de Calcium Monohydrate la

Calcul Mixte Oxalate Calcium Mono et Dihydrate la+lla

Calcul Acide Urique llb

Les lithiases urinaires

Introduction

  • La lithiase rénale est une maladie qui consiste en la formation des calculs dans les voies urinaires.

  • La lithiase occupe une place importante en urologie de part :

    • sa fréquence

    • sa diversité et ses aspects cliniques

    • la discussion thérapeutique qu’elle impose

Diagnostic & Treatment Considerations

  • Diagnostic is generally easy, typically achieved via radiological assessment.

  • Key questions to address with any renal lithiasis:

    • Is it a severe lithiasis? Consider mechanical and infectious repercussions and instances where the patient or kidney's prognosis is at stake.

    • What is the cause of the lithiasis? Investigate metabolic causes, possibly linked to organic causes, where treatment can prevent lithiasic recurrence.

    • What treatment is appropriate? Options include extracorporeal lithotripsy, percutaneous surgery, and endo-urology.

Etiopathogenesis: Lithogenesis

  • A calculus is an agglomerate, ordered or not, of crystalline or amorphous particles, precipitated in the urine, connected and maintained by an organic matrix of essentially protein nature.

The Four Steps of Calculi Formation

  • Nucleation: Formation of crystals by precipitation of dissolved substances in urine.

  • Crystal Growth: Influenced by supersaturation, nature/concentration of growth inhibitors, and the crystal's structure.

  • Crystal Aggregation: Crystals assemble around a nucleus (e.g., papilla fragments, protein matrix).

  • Crystal Retention: Occurs in areas of slow urinary flow (anatomical anomalies) or when crystals fix to cell membranes due to epithelial rupture.

Saturation and Urine

  • Saturation of Urine: Maximum solute concentration beyond which precipitation occurs.

  • Supersaturation of Urine: Solute concentration exceeds the saturation point.

Types of Calculi

  1. Calcic Calculi

    • Calcium Oxalate: Most frequent.

    • Calcium Phosphate

    • Hydroxyapatite

  2. Non-Calcic Calculi

    • Uric Acid

    • Cystine

    • Struvite (phospho-ammoniaco-magnesium)

Factors Favoring Lithogenesis

  1. Dietary Factors

    • Excessive intake:

      • Dairy products: Promote hypercalciuria.

      • Animal proteins: Promote hypercalciuria.

      • Salt: Promotes hypercalciuria, blocks crystallization inhibitors.

      • Foods rich in oxalates (chocolate, dried fruits, spinach, sorrel, rhubarb, tea, gelatin-rich candies which contain hydroxyproline, a precursor of oxalate).

      • Purines (offal, cold cuts,…).

      • Rapid sugars such as fructose (promotes hypercalciuria, hyperuricurie).

    • Decreased consumption of dietary fibers.

  2. Hyperconcentration of Urine:

    • Excessive intake (dietary, medicinal).

    • Excessive production by endogenous metabolism.

    • Excessive urinary excretion (Cystine).

    • Decrease in solvent, low diuresis

  3. Familial Factors:

    • More than a third of lithiasic cases.

    • Hereditary lithiasis: Cystinuria is the most frequent lithiasic disease of genetic origin.

  4. Urinary Infection:

    • Certain urease-producing germs cause the formation of phospho-ammoniaco-magnesium calculi.

  5. Urinary pH Anomalies:

    • Normal urine pH is 5.7.

    • Acidic pH (~5) favors uric acid, cystine, and calcium oxalate calculi.

    • Alkaline pH (~7) favors infection and phosphocalcic calculi.

  6. Anatomical Anomalies:

    • Ureteropelvic junction syndrome, diverticulum, horseshoe kidney, megaureter. Treat the calculus and the anatomical anomaly if possible.

  7. Medications:

    • Indinavir, cotrimoxazole, allopurinol, amiodarone, thiazide diuretics, vitamin D.

Morpho-Constitutional Analysis

  • Analysis informs about the origin of the calculus.

  • Crucial for etiological diagnosis of lithiasis.

Clinical Study: Circumstances of Discovery

1.1 Urological Manifestations
* Nephritic Colic: Very evocative, often starts suddenly at night or early morning, located in the lumbar fossa and the costovertebral angle along the lower border of the 12th rib, antero-inferior irradiation towards the groin and external genitalia. No triggering or aggravating factors for the pain; no factor calming the pain. Disappearance of crises: the natural evolution of colic, spontaneous expulsion of the calculus.
* Hematuria: 20% of cases, macroscopic or microscopic, isolated or associated with pain, urinary signs or infection, most often total, of effort, occurring at the end of the day secondary to the displacement of the calculus
* Emission of a Calculus: May reveal other renal lithiases.
1.2 Complications: Mechanical or infectious.
1.3 Fortuitous Discovery:
* Well-tolerated calculus, asymptomatic patient.
* Calculus discovered during the exploration of another pathology.

Patient History

  • Familial history of urinary lithiasis; personal history of nephritic colic, hematuria of effort, spontaneous emission of sand, urological antecedents (malformations, renal cysts, infections, surgery).

  • Certain treatments can be responsible for metabolic or drug-induced calculi, dietary and beverage habits.

Physical Examination

  • Temperature check, intense sensitivity with pain on lumbar impact, urine appearance, check if the patient maintains diuresis. Oligo-anuria requires urgent treatment.

Radiological Examinations

  • Plain Abdominal X-ray: An opacity of calcic tonality, projecting on the renal area or the path of the ureter may correspond to a calculus, radio-opaque.

  • Ultrasound: Confirms the clinical diagnosis of nephritic colic by objectifying a dilation of the pyelocaliceal cavities and the ureter.

  • Tomodensitometry (CT Scan): The reference examination for the exploration of urinary lithiasis.

Etiological Diagnosis

  • Morpho-constitutional analysis of the calculus: First step of the metabolic assessment, infrared spectrophotometry: crystalline and chemical composition of the calculus, can resolve the etiological problem immediately in case of specific composition.

Diagnostic Tests

  • 24h Urine: Creatinine, calcium, uric acid, urea, sodium, total diuresis.

  • Morning Urine: Density, urinary pH, crystalluria, dipstick or ECBU.

  • Blood work: Creatinine, calcium, uric acid, fasting blood glucose.

Calculus Morphology

  • Surface: mammelonée ou lisse, brun à brun foncé

    • Etiologies: Hyperoxafurie diététique, Défaut de diurèse, Hyperoxalurie concentration, Plaque Randall

  • Surface: mamelonnée et rugueuse, mamelons & creuxx.

    • Etiologies: Défaut de diurèse, stase urinaire, conversion cristalline totale

  • Surface: grenue, bourgeonnante au mamelonnée, couleur claire, blanche à brun-jaune.

    • Etiologie: Hyperoxalarie primaire

  • Surface: lisse, homogène-faces d'accolement-brun-jaune ± clair.

    • Etiologies: Uropathie malformative. Stase urinaire et confinement anatomique

  • Surface: mamelonnée, localement bourgeonnante, couleur brun-jaune clair à brun clair

    • Etiologies: Hyperoxoluries entériques, Maladies inflammatoires Digestives (Crohn) Grêle court Pancreatite chronique

Differential Diagnosis

  • Urological Conditions:

    • Acute pyelonephritis, Renal infarction, Papillary necrosis, Acute scrotal pain.

  • Non-Urological Conditions:

    • Fissure of an aortic aneurysm or its branches, Aortic dissection, Ectopic pregnancy, Ovarian cyst torsion, Torsion of the spermatic cord, Ileocolic and appendicular affections (mesenteric infarction), Acute pancreatitis, Hepatic colic, Basal pneumonia, Acute low back pain.

Treatment of Nephritic Colic

  • Non-steroidal anti-inflammatory drugs (NSAIDs) parenterally (IM/IV) with oral relay after sedation.

  • Hydric Restriction: Maintain restriction until the calculus has been eliminated, even if pain has subsided.

  • Monitor diuresis and temperature. Urine is strained to recover the calculus if emitted.

  • Supine abdominal X-ray and renal and retrovesical ultrasound visualize the calculus and monitor its migration.

Urological Treatment of Calculi

  • Principle: Rid the excretory tract of the calculus and correct any congenital or acquired anomalies that may promote lithogenesis.

  • Treatment is done remotely from an acute episode.

  • Treatment methods: complementary.

Extracorporeal Shock Wave Lithotripsy (ESWL)

  • Principle: Fragment the calculus by shock waves from an extracorporeal generator. The shock waves are directed at the calculus using radiological and ultrasound imaging, and by cavitation phenomena, cause its fragmentation. The intervention is done on an outpatient basis under sedation-analgesia. The fragments produced must be fine enough to be eliminated without difficulty through natural channels.

Additional Calculus Treatments

  • Ureteroscopy: Rigid or flexible optical instruments penetrate the ureter retrogradely (uretovesical) to treat renal and ureteral calculi. Calculi are treated using fragmentation devices (laser, pneumatic lithotripter), and fragments are removed with a basket.

  • Percutaneous Nephrolithotomy (PCNL): A technique that creates one (or two) tunnel(s) between the skin and a calyx through the renal parenchyma, allowing the treatment of large calculi by introducing an optical instrument called a nephroscope and fragmenting the calculi with a laser or contact ultrasound procedure. The fragments are then extracted with a forceps or a basket.

  • Open Surgery and Coelioscopy: Addressed to very large renal and ureteral calculi that cannot be treated effectively by the methods described above. These calculi have become rare.

Medical Treatment of Lithiasis

  • Seeks to prevent recurrence of calculi after identification of the type of lithiasis and, in some cases (uric acid), allows their dissolution. It consists of hygienic-dietary rules:

    • Drinking at least 2 liters per day, more if it is hot or in case of sports activities.

    • Regular physical activity.

    • Avoid excess calories.

    • Vary diet and consume fibers (fruits and vegetables).

    • Reduce protein intake.

  • Urinary Alkalinization: Dissolves uric acid calculi and, to a lesser extent, cystine calculi (30 to 40%). Urine should be alkalinized with bicarbonate-rich waters. Sodium bicarbonate can also be prescribed to be diluted in water for uric acid or cystine calculi. In case of hyperuricemia and/or hyperuricurie, a background treatment based on Allopurinol should be associated.

  • Thiazide diuretics: in case of idiopathic hypercalciuria.

  • For cystine calculi, D-penicillamine is prescribed, which aims to complex cysteine by forming with it a compound soluble in alkaline urine.

Conclusion

  • Renal Lithiasis

    • Types of renal lithiasis

      • Phosphate-based lithiasis (20%)

      • Oxalo-calcium lithiasis (67%)

      • Cystine lithiasis and others (5%)

      • Uric acid lithiasis (8%)

    • Signs and symptoms

    • 1 in 10 people affected by lithiasis

    • Risk factors

      • Genetics

      • Overweight

      • Dehydration

      • Vomiting

      • Fever

      • Medications

      • Diet