Nephrolithiasis or Renal Calculi is a solid aggregation of crystals formed in the urine by the dietary minerals in the kidneys. Kidney stones consist generally of calcium salts, uric acid, struvite, or cystine. Stones form in the urine which is super-saturated concerning the specific stone’s ionic components and saturation depend on chemical-free ion activities.

A drop in free ion activity may induce under-saturation of the urine, a condition in which the stone does not expand and may even dissolve. An increase in the production of free ions would cause the urine to become super-saturated, a condition that would encourage a stone to shape or expand in size.

CLASSIFICATION

TYPES OF KIDNEY STONES

CALCIUM STONESThey are the most common type. They occur in two forms: 1) Calcium Oxalate    2) Calcium Phosphate
URIC ACID STONESThey form when the urine is acidic. A diet rich in purines increases uric acid in urine. Purines are substances found in animal protein, such as meats and fish.
STRUVITE STONESThey form in infected bladder and kidneys.
CYSTINE STONESThey result from a genetic disorder that causes cystine to leak into the urine. Cystine then forms crystal and stones.
TYPES OF KIDNEY STONES

EPIDEMIOLOGY

Globally, the prevalence and rate of recurrence of kidney stone disease are growing. At some stage in their lifetime, nephrolithiasis affects about 12 per cent of the world population. It affects all ages, sexes, and races but occurs more often in men than in women aged 20–49.

PATHOPHYSIOLOGY

  • Kidney stone formation pathophysiology is complex and involves a range of metabolic, genetic, and environmental influences. Regardless of the supersaturation of urine by stone-forming components, including calcium, oxalate and uric acid, kidney stones happen. Supersaturated solution refers to a solution of more soluble content than a solvent would usually be able to dissolve. Crystals or foreign bodies acting as nidi on which microscopic crystalline structures are created by supersaturated urine ions. The resulting calculi give rise to symptoms when they are impacted within the ureter, as they pass into the bladder with urine. The sequence of events triggering stone formation can be classified into the following four stages:
  • STAGE I: Crystal Nucleation
  • STAGE II: Crystal Growth
  • STAGE III: Crystal Aggregation
  • STAGE IV: Crystal Retention

CLINICAL MANIFESTATIONS

  • Abdominal Pain
  • Back Pain
  • Pain during Urination
  • Nausea and Vomiting
  • Hematuria
  • Burning sensation during urination
  • Problem in Voiding

DIAGNOSIS

  • Ultrasound
  • Computed Tomography (CT) Scan
  • KUB-X Ray
  • Intravenous Pyleography (IVP)

RISK FACTORS

GeneticIdiopathic hypercalciuria
Hyperoxalosis
Dent’s disease
Kidney disease relatedMedullary sponge kidney
Polycystic Kidney Disease
Hypercalcemia Hyperparathyroidism Diabetes Mellitus
Obesity
Systemic diseaseInflammatory bowel diseases
Dietary      Sodium
Oxalate
Protein (animal)
Acid / alkaline ash diet
Fluid
Potassium and citrate
Vitamins (C, D)
Calcium supplement
Low Calcium diet
High protein weight-loss diet
ClimateHeat
Water loss
RISK FACTORS FOR KIDNEY STONE FORMATION

TREATMENT

NON-PHARMACOLOGICAL TREATMENT

HYDRATION

The urine production is reduced with low fluid intake and the urine flow is slower, all of which increase the likelihood of stone formation.

CITRIC ACID

The ingestion of fruit juice prevents the development of stones not only because it raises the production of urine but also because it is rich in potassium and citric acid.

CALCIUM

There is a common belief that decreasing calcium intake would reduce the risk of formation of calcium stone. With low calcium intake, the digestive tract does not contain enough calcium to bind with oxalate, resulting in increased absorption of oxalate and excretion of urinary oxalates.

VITAMINS

Vitamin C increases the concentration of urine oxalate at the super-dosages found in supplements because ascorbic acid is metabolized to oxalate.

PHARMACOLOGICAL TREATMENT

TYPE OF KIDNEY STONEMEDICATION
CALCIUM STONESPotassium Citrate – which is used to raise the citrate and pH levels in urine
Diuretics – often called water pills, helps rid your body of water
URIC ACID STONESAllopurinol – which is used to treat high levels of uric acid in the body
Potassium Citrate
STRUVITE STONESAntibiotics
Acetohydroxamic Acid
CYSTINE STONESMercaptopropionyl Glycine
Potassium Citrate
PHARMACOLOGICAL TREATMENT FOR KIDNEY STONES

SURGICAL TREATMENT

  • Extracorporeal Shockwave Lithotripsy
  • Ureteroscopy
  • Percutaneous Nephrolithotomy

OTHER SURGERIES

Such operation to the kidneys is rarely used to remove stones. If all other less invasive techniques fail,  open laparoscopic or robotic surgery can be used.

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