Question

Correlate physical and chemical urinalysis results with microscopic observations and recognize discrepancies.

Answer 1

Ans. Urinalysis is a reflection of concentration-dependent excretion and abnormal renal function. Testing is used to screen for, diagnose, and monitor patients with certain conditions

Urinalysis is the physical, chemical, and microscopic examination of urine. It involves a number of tests to detect and measure various compounds that pass through the urine.

PHYSICAL COLOR AND APPEARANCE

How the urine sample looks to the naked eye:

Is it clear or cloudy

Is it pale, or dark yellow, or another color

MICROSCOPIC APPEARANCE

The urine sample is examined under a microscope to: Check if there are any cells, urine crystals, urinary casts, mucus, and other substances. Identify any bacteria or other germs.

CHEMICAL APPEARANCE (urine chemistry)

A special strip (dipstick) is used to test for substances in the urine sample. The strip has pads of chemicals that change color when they come in contact with substances of interest.

The most cost-effective device used to screen urine is a paper or plastic dipstick. This microchemistry system has been available for many years and allows qualitative and semi-quantitative analysis within one minute by simple but careful observation. The color change occurring on each segment of the strip is compared to a color chart to obtain results. However, a careless doctor, nurse, or assistant is entirely capable of misreading or misinterpreting the results. Microscopic urinalysis requires only a relatively inexpensive light microscope.

MACROSCOPIC URINALYSIS

The first part of a urinalysis is direct visual observation. Normal, fresh urine is pale to dark yellow or amber in color and clear. Normal urine volume is 750 to 2000 ml/24hr.

URINE DIPSTICK CHEMICAL ANALYSIS

A dipstick is a paper strip with patches impregnated with chemicals that undergo a color change when certain constituents of the urine are present or in a certain concentration. The strip is dipped into the urine sample, and after the appropriate number of seconds, the color change is compared to a standard chart to determine the findings.

Correlation of Results : Once the microscopic examination is completed, it is important to decide whether the results are normal or abnormal. Correlation involves comparing the microscopic findings with the macroscopic findings. If the results are consistent with each other, the urinalysis may be reported. If a discrepancy exists, the microscopic results cannot be reported. The findings that do not correlate must be repeated.

INTERPRETATION OF URINALYSIS FINDINGS.

It is essential to correlate the physical, chemical, and microscopic findings of urinalysis reports. A working knowledge of kidney function is essential to correlating the findings. A pale, clear urine with a low specific gravity, pH of 6.0, an essentially negative dipstick, and an occasional epithelial cell in the microscopic examination describes a random specimen from a healthy male (unless it is a catheterized specimen) individual. Conversely, a cloudy, smelly urine specimen with protein, white blood cells both on the chemical tests and microscopic exam, and some cellular casts may indicate some type of renal disease.

If there were no casts present in the microscopic examination of the above specimen, contamination on voiding and the time of the specimen collection would have to be considered. When interpreting urinalysis results, considerations must be made for the possibility of false-positive and false-negative results. When urinalysis findings are not supported by other clinical observations, consult the laboratory for possible sources of false results.