المكونات الطبيعية لراسب البول

عدد المساهمات : 18 تاريخ التسجيل : 05/06/2012

Under normal conditions, the urine of healthy people contains a number of erythrocytes, leukocytes and hyaline casts, yet there is no precise information as to the upper limit of the normal cell range counts in urine excreted daily. This lack of data is due in part to technical problems and to the wide variation from one individual to another, and in part to the considerable variability in the percentage of cells and casts that are destroyed and consequently not counted; the extent of this loss depends on the phvsicochemical conditions of the urine and the length of time these elements remain in it.

Quantitative assessment is therefore only empirical and approximate; nonetheless, for conventional volumes of 1250 ml of urine voided per day, it is generally agreed that the approximate, acceptable maximum limits for normal urine are 500 erythrocytes/ml, 2000 leukocites/ml and less than 15 hyaline casts/ml. Since the various techniques for obtaining total counts are too time-consuming for routine examination, they have not come into common use and an estimate of the average number of elements in highly magnified microscopic fields (generally 400x) is preferred.
This is more approximate and even less reliabie assessment since iy is based on a technique which introduces an additional number of variables, partly determined by chance (e g. dilution ot the urine) and partly connected with the execution of the test. The latter is often be no means standardized: there may be variations in the volume of urine centrifuged, the time and speed of centrifugation, the volume of the supernatant, the drop of urine examined, etc.
If, however, one does not intend to fix precise limits for normal and abnormal values, or to inaccurate comparisons of the different examinations, this type of semi-quantative test does provide quite a good practical basis for assessment.
Erythrocytes and leukocites are not found in the sediment of some healthy people; yet, although opinions differ, one red cell, one to two leukocytes and only an occasional hyaline cast are generally taken, in a rather arbitrary way, to indicate the upper normal limit for each high magnified microscopic field observed (400x).
These are, of course, only approximate values.
Before drawing any definite conclusion, all borderline results require

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عدد المساهمات : 285 تاريخ التسجيل : 18/03/2011

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