Urinalysis Flashcards Preview

MIDW127 - Beginning the Journey > Urinalysis > Flashcards

Flashcards in Urinalysis Deck (16):


- Test the characteristic and composition of freshly voided urine
- Screening for disease
- Diagnosis of a suspected condition
- Management and monitoring progress of a condition



- Colour (Pale to amber Vitamin B supplements can turn urine bright yellow. Some medicines, blackberries, beets, rhubarb, or blood in the urine can turn the urine red-brown)
- By-product of haemoglobin breakdown, urochrome, gives colour
- Affected by concentration, haematuria, diet
- Clarity usually transparent, if cloudy, no fresh, proteinuria, infection, bacteriuria
- Odour - characteristic inoffensive (stronger/offensive if left stagnant or infection present. Sweet if ketones are present)


Significance of Composition

- 96% Water + 4% Dissolved Substances
~ Urea
~ Uric Acid, Creatinine, Sodium, Potassium, Chlorides, Sulphates, Phosphates
~ Epithelial Cells, Leukocytes
- pH of 4.5-8
- pH measures degree of acidity to alkalinity of urine
- Low pH means more acid


Specific Gravity

- Specific Gravity reflects the kidney's ability to concentrate or dilute urine
- Want more concentrated urine for accurate testing, best is first morning urine sample
- Low SG means the urine is not concentrated and kidney disease could be present
- High SG could mean the sample is first morning urine, certain drugs may be taken, or dehydration



- Bilirubin is a byproduct of the breakdown of haemoglobin
- Urine normally contains no Bilirubin
- Presence may be an indication of liver disease, bile duct obstruction, or hepatitis
- A false positive may result when certain drugs are taken
- A false negative may occur when the sample is exposed to sunlight



- Presence of blood in the urine may indicate infection, trauma to the urinary tract, or bleeding in the kidneys
- False positive readings are most often due to contamination with menstrual blood
- A positive result will result in further investigation



- Presence of Glucose (glycosuria not uncommon during pregnancy) indicates that the blood glucose level has exceeded the renal threshold
- Renal threshold lowers in pregnancy
- Useful to screen for diabetes



- Ketones are excreted when the body metabolises fats incompletely (ketonuria)
- May occur due to fasting, vomiting (hyperemesis gravidarum) uncontrolled diabetes
- Some drugs (Captopril) may give a false positive



- Leukocytes (white blood cells) usually indicate infection
- Specimen may be contaminated by Leukocytes from another source (Vaginal Discharge)
- When found with nitrates, bacteriuria is strongly suggested



- Indicative of UTI
- Diet source of Nitrates in urine in presence of Bacteria
- Formed by gram negative bacteria converting urinary nitrate to nitrite



- Presence of protein (proteinuria) is an important indicator of renal disease
- Transient positive test usually insignificant due to small amount of albumin and globulin in the urine
- May also result from contamination, vaginal discharge which increases during pregnancy



- Urobilinogen is a degradation product of bilirubin formed by intestinal bacteria
- It may be increased in hepatic disease or haemolytic disease
- Normally present in small amounts


Normal Values

- Negative results for glucose, ketones, bilirubin, nitrites, leukocyte esterase and blood
- Protein negative or trace
- pH 5-8.0
- Urobilinogen 0.2-1.0 Ehrlich units


Handling & Storage

- Keep strips in original container
- do not touch reagent pad areas
- Reagents and strips must be stored properly to retain activity
- Protect from moisture
- Store at room temperature
- Use before expiration date
- Lid on tightly



- Dip strip completely into well mixed, room temperature fresh urine sample
- Withdraw strip
- Blot briefly on its side
- Keep the strip flat, read results at the appropriate times by comparing the colour to the appropriate colour on the chart provided



- Timing - Failure to observe colour changes at appropriate time intervals may cause inaccurate results
- Lighting - Observe colour changes and colour charts under good lighting.
- Sample - Proper collection and storage of urine is necessary to insure preservation of chemical
- Testing Cold Specimens - Would result in a slowing down of reactions; test specimens when fresh or bring them to RT before testing
- Inadequate Mixing of Specimen - Could result in false, reduced, or negative reactions to blood and leukocyte tests; mix specimens well before dipping
- Over-dipping of Reagent Strip - Will result in leaching of reagents out of pads; briefly, but completely dip the reagent strip into the urine.