Urinalysis

Regarding urinary chemical reagent dipstick testing, the following are true EXCEPT

which one?

a) The presence of leucocytes with no nitrites is more common than the presence of

nitrites with no leucocytes

b) Urine specific gravity measurements may need to be adjusted upwards if the

urine is strongly acidic

c) If the stick is left with a coating of excess urine after dipping, errors are most likely

to be found in the pH reading

d) Concurrent nephrotic syndrome may lead to overdiagnosing the syndrome of

inappropriate antidiuretic hormone (SIADH) when analysing dipstick specific

gravity

e) If the urine is allowed to stand for one hour, glucose testing may produce a false

negative

Answer: b

Explanation

Nitrites are often found on urine dipsticks during infection as bacteria convert nitrates to nitrites. This is not the case for all bacteria, so the absence of nitrites does not equal the absence of bacteria. Specific gravity is in the range of 1.001 to 1.035 in health. Strongly acidic urine may raise the dipstick measurement of specific gravity so values may have to be adjusted downwards. If the stick is left with an excess of urine, errors are most likely to be seen on the pH recording as there may be run-off from the strongly acidic protein test pad. Dipstick measurement may read high specific gravity in the presence of ketones or protein in the urine. If the investigator is using dipsticks to aid with diagnosing SIADH, the proteinuria found in nephrotic syndrome may lead to a false positive diagnosis. If urine is allowed to stand, for any length of time, bacteria may use up any glucose for metabolism, rendering abnormally high glucose levels undetectable.