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| SUBJECT |
What happen if the urinalysis test is performed after 2 hours from the sample collection? |
| DATE |
2010.04.28 |
HIT |
8610 |
FILE |
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Urine test with strip should be carried out within 2 hours after micturition. Long standing times in the air can lead to a false result and it is caused by the following influence*2 :
l Disintegration (lysis) of leucocytes and erythrocytes
l Proliferation of bacteria
l Bacterial degradation of glucose
l A rise in pH due to ammonia formed as a result of bacterial degradation of urea
If the urine is kept in a sealed container in a refrigerator, the change in the specimen can be slowed down as followings.
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Substance
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Stability in urine
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Change of result
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20~25℃
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4~8℃
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Falsely increased
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Falsely decreased
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Blood
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1~4 h
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1~4 h
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Fast lysis at density <1.010
and pH>7
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Bilirubin
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2 h
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Unstable in light
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Oxidation to biliverdin
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Urobilinogen
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2 h
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Unstable in light
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Oxidation to urobilin
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Ketones
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2 h
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6 h
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Change from acetoacetic acid to acetone by bacteria
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Protein
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1 day
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7 days
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Nitrite
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4 h
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8 h
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Bacteria increased
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Change from nitrite to nitrogen
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Glucose
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2 h
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8 h
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Glycolysis by bacteria action
or cells
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pH
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Unstable
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Unstable
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Ammonia formed as a result of bacterial degradation of urea
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Leucocytes
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1~4 h
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1~4 h
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Falsely increased in a certain blennuria after 1hour
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Fast lysis at density <1.010
and pH>7
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