Examination of Urine for Normal
Constituents^7
Urine is the excretory product of the body produced by the process offiltration,
reabsorption, and tubular secretion. Urine can be collected and examined easily, and
presence of certain substances in the urine may indicate the metabolic state of the
body. The routine and microscopic examinations of urine are helpful in the diagnosis
of several pathological conditions. Urine sample is collected in clean vials. A
random sample is usually taken for routine clinical examination; however,first-
morning urine is preferred for urinalysis and microscopic analysis, since it is
generally more conc. Timed collection specimens may be required for quantitative
measurement of certain analytes. Fresh or preserved urine samples are used for
chemical and culture-based microbiological testing. The specimens that are
unpreserved for more than 2 h or refrigerated for a long time may not be suitable
for analysis due to potential bacterial overgrowth and invalidation of bacterial
colony counts or errors in chemical urinalysis.
7.1 Preservatives Used for Urine Collection
The commonly used preservatives for urine sample collection in clinical biochemis-
try laboratory are:
- 6 N HCl in proportion of 10 ml/24 h urine
- Few drops of formalin in 30 ml of urine
- 50% acetic acid
- 6 N HNO 3
- Boric acid, toluene, Na 2 CO 3
#Springer Nature Singapore Pte Ltd. 2018
V. Kumar, K. D. Gill,Basic Concepts in Clinical Biochemistry: A Practical Guide,
https://doi.org/10.1007/978-981-10-8186-6_7
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