الفهرس 
introdutionOnly 14 pages are availabe for public view
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Abstract
Calcium stones are the most common types of kidney stones either calcium oxalate or calcium phosphate. Calcium oxalate stones are more common than calcium phosphate stones. The frequency of recurrent calcium urolithiasis is greatest in the fourth and fifth decade of life. In addition, recurrence occurs more often in males than females with a ratio of two to one respectively. There are naturally occurring substances in urine, which inhibit the process of stone formation. The urinary stone inhibitors are of two types: 1 The chelating inhibitors such as magnesium. 2 The polyanionic macromolecular inhibitors such as Tamm Horsfall glycoprotein that contain sialic acid as carbohydrate moiety. The present study showed that: ?The most common type of stone is calcium oxalate. The frequency of urolithiasis is high in ages between 40 to 50 years and the prevalence of urolithiasis in men is higher than that in women. The magnesium excretion results were similar in recurrent kidney stone patients and controls. ?The patients<U+2019> bound sialic acid excretions were significantly low as compared with those of controls, while, the patients? sialidase activity was significantly high compared to control results. On the other hand, the TammHorsfall glycoprotein excretion in patients resembled those of the control group. ?There was a significant decrease in patients<U+2019> daily, excretion of free sialic acid as compared with that of controls. In addition, there was insignificant decrease in the daily excretion of patients? total sialic acid compared with that of the control group. The daily excretion of calcium, phosphorus and oxalate were similar in recurrent kidney stone patients and controls. In conclusion, TammHorsfall glycoprotein had decreased sialic acid content in recurrent kidney stone patients, which may explain the dual role of THP. Depending on the glycosylations THP acts as an inhibitor or promoter of calcium oxalate precipitation and thus of the renal stone formation process. ?The kidneys of recurrent kidney stone patients excrete less sialic acid than controls and the urinary sialidase activity of patients is higher than that of controls. This observation may support the hypothesis that the first step in the conversion of mucosubstances to mineralizable matrix may be the removal of sialyl groups from uromucoid moieties.