Tuesday, June 30, 2009



In laboratory experiment, urinary stone can be regularly produced by diets low in vitamin A. It may be secondary to the epithelial degeneration which occurs in vitamin A deficiency in rats.
In patients with hyperparathyroidism, the urinary stone formation may be related the markedly increased excretion of calcium in the urine.
Stone formation appears often to be secondary to in infection in the kidney. Clumps of bacteria and epithelial and pus cells may act as the nuclei for stone formation.
During World War II, in troops living in a hot dry climate, with inadequate water intake and a diet containing vegetables with a high oxalate content, oxalate crystals may be precipitated in urinary tract. These crystals are irritants and may produce gross hematuria [blood in the urine], symptoms of renal or kidney colic or and cystitis. On cystoscopy [visual examination of the bladder] there is an intense inflammation, and oxalate crystals can be seen embedded in the mucosa. The fibrin formed as a result of bleeding provides a matrix for the formation of calcium oxalate stones. Unless obstructive stone have been formed, the symptoms of oxalate in the urine are relieved promptly by an increased fluid intake.
The other stones appear, however, to arise in aseptic urine, begin when urine become super-saturation with insoluble components due to low volume, excessive excretion of selected compound, and changes of pH [pH 7 is neutral, less than 7 is acid and more than 7 is base or alkaline solution].
Approximately 75 % of stones are calcium-based [ the majority are calcium oxalate, calcium phosphate and other mixed stones], 15 % struvite [magnesium-ammonium-phosphate], 5 % uric acid and 1 % cystine, depending on the metabolic disturbances from which they arise. Struvite is the most common component of stag-horn stone.
The surface of stone such as uric acid,, carbonate, cystine stone are generally smooth. The surface of calcium oxalate stones and phosphate stone are generally rough; the large stone of calcium oxalate is uneven surface, which is classed as a mulberry stone.
In determining the nature of the sediment or stone formed the pH is a control factor.
Determination of urine solution by litmus paper as indicator: acid urine turns the litmus to red color, and base or alkali urine turns the litmus to blue color.
Uric acid tends to precipitate when acidity becomes high at pH 5, At pH 6 mixed stones of uric acid, sodium urate, calcium oxalate and phosphate will tend to form. At pH 7 calcium phosphate tend to form, between pH 7 and 8 with the urine ammoniac mixed stone of calcium phosphate, magnesium ammonium phosphate, and ammonium urate may form; at high alkali pH 8 or above 8 tend to produce stones containing calcium carbonate, ammonium magnesium phosphate and ammonium urate.
So that the causes of kidney stones are classified :
• Excessive intake and excretion of relatively insoluble urinary constituents
• Increased concentration or super-saturation of urinary constituents when fluid intake is low
• Nucleus [Nidus] for stone formation: Organic material, such as bits of necrotic tissue, blood clot [fibrin], clumps of bacteria if accompanied by infection.
• The nature of the kidney stones formed, the pH is a control factor.


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