Written by DrShailesh Doshi

Urinary stones are excessive production of urinary crystaloids.

Causes

Exact cause is not known. But many theories have been put forward in connection with the causation of the stones.

1. Dietary facors:
   It is said that when diet is deficient in Vitamin A, the person gets prone to the formation of stones.


2. Infection:
   When there is infection present in the urinary tract, the bacteria, some pus cells and the mucous membrane clump together, and crystals of stones are deposited around that and form the stones.


3. Metabolic Disorders
   In metabolic disorders excessive amount of crystals are passed in higher quantity; there is tendency to precipitate and thus stone formation.


4. Obstruction to urinary flow
   Due to any cause and anywhere, in the urinary tract i.e. when the flow becomes slow; e.g.stricture of urethra or enlargement of prostate gland pressing on the urethra.


5. Immobilisation or Recumbency
   When the patient does not move about i.e. lying stationary in bed for a long time, as in fracture especially of the spine, caries spine, sciatica, general debility, paraplegia and hemiplegia, i.e. whenever a part is kept at rest for a long time, it undergoes wasting. Calcium of bones starts coming in the blood; when it increases in the blood, it starts coming in the urine and it causes concentration of more calcium, leading to formation of the stone.


6. Pathological Conditions
   Hyper-parathyroidism: They are four small glands of the pea nut size situated behind the thyroid. Calcium metabolism is under its control. When its activity is increased, it removes the calcium from the bones and also from the kidneys and send it into the blood, which further comes into the urine, causing formation of the stones. They are always multiple and bilateral.

Types of Stones

There are basically 2 types.

Primary	Secondary
Arise in apparently healthy urinary tract	Form in infected urine
Form in acidic urine	Form in alkaline urine
Composed of substances present normally in urine Oxalate Uric Acid Cystine Atone	Composed of substances not normally present in urine Magnesium Ammonium Phosphate

Calcium Oxalate Stones

• They are usually single, small hard irregular spikes projecting from the surface; they are opaque to X-ray.


• They are also known as Mulberry stones.


• As they are covered by sharp projections they cause bleeding and are blackish brownish in color.


• These little stones cause symptoms early.


• They are seen in acidic urine. So, to prevent their increase or to dissolve them, the urine must be made alkaline.

Phosphate Stones

• They are usually secondary stones-formed in infected urine.


• They are smooth, dirty white in colour.


• They often enlarges rapidly taking on shape of renal calyces-staghorn calculus.


• Although they are very large, due to their smooth surface, they may not cause much symptoms.


• They are seen in alkaline urine.

Uric Acid and Urates Stones

• These stones are hard and smooth


• They are multiple, small, friable.


• Colour varies from yellow to reddish brown.


• Uric acid stones are the only stones which do not appear in X-ray.

Cystine Calculi

• They are multiple, hard and pink or yellow in colour. On exposure their colour changes to greenish hue.


• They are seen in X-ray


• They are hexagonal and form only in acidic urine.

Xanthaine

• They are extremely rare, smooth, round, brick red in colour.