Medicine Study: Urinalysis Terms & Definitions

readily available, inexpensive to test

Two characteristics of urine that make it an ideal laboratory specimen

organic: urea, creatinine, uric acid

inorganic: chloride, sodium, potassium

List three major organic and three major inorganic chemical constituents of urine

Amount of creatinine and urea

Describe a method for determining whether a questionable fluid is urine

Oliguria

decrease in urine output; associated with vomiting, diarrhea, perspiration, severe burns

nocturia

increased urine output at night; present in older adults, pregnant women

anuria

cessation of urine flow; associated with seriously damaged kidneys

polydipsia

increased ingestion of water; associated with diabetes mellitus

diabetes mellitus

What disorder is apparent if a patient reports polyuria, nocturia, polydipsia, and has a high specific gravity?

disposable, wide-mouthed, flat bottom, screw cap, clear, at least 50 mL, clean, dry, leak-proof

What are the recommended characteristics of an urine specimen container?

50 mL; this is enough for microscopic testing (12mL), while still having enough left over for other analyses; also large enough to mix urine by swirling container

What size should an urine specimen container be and why?

It eliminates the possibility of contamination due to improper washing

Why should urine specimen containers be disposable?

unlabeled, improperly labeled, contaminated, insufficient quantity, improperly transported

Why might a lab reject a urine specimen?

The sample should be labeled at bedside, and the label should not be placed on lid to prevent samples being mixed up

Where should a urine sample be labeled, and where should the label not be place? Why?

The color would darken due to oxidation and/or reduction of metabolites

If a urine specimen is left out at room temp for 2 hours, how and why would the color change?

The clarity would be decreased (would become cloudier) due to bacterial growth and precipitation of amorphous material (dissolved substanceds would un-dissolve)

If a urine specimen is left out at room temp for 2 hours, how and why would clarity change?

The odor would increase due to bacterial growth and the breakdown of urea to ammonia (causing ammonia smell)

If a urine specimen is left out at room temp for 2 hours, how and why would odor change?

The pH would increase (become more alkaline) because of urea breakdown into ammonia

If a urine specimen is left out at room temp for 2 hours, how and why would pH change?

The glucose would decrease due to bacterial use/glycosis

If a urine specimen is left out at room temp for 2 hours, how and why would glucose change?

Ketones would decrease due to bacterial metabolism

If a urine specimen is left out at room temp for 2 hours, how and why would ketones change?

Bilirubin would decrease due to exposure to light/oxidation

If a urine specimen is left out at room temp for 2 hours, how and why would bilirubin change?

urobilinogen would decrease due to oxidation

If a urine specimen is left out at room temp for 2 hours, how and why would urobilinogen change?

Nitrites would increase due to multiplication of nitrite-reducing bacteria

If a urine specimen is left out at room temp for 2 hours, how and why would nitrite change?

They would decrease because they would disintegrate

If a urine specimen is left out at room temp for 2 hours, how and why would red and white cells and casts change?

It would increase as the bacteria multiplied

If a urine specimen is left out at room temp for 2 hours, how and why would bacteria change?

They would decrease because of loss of motility, death

If a urine specimen is left out at room temp for 2 hours, how and why would trichomonas change?

pH, nitrite, and bacteria

three parameters of routine urinalysis that are falsely increased if specimen is not tested within 2 hours

increased bacteria, decreased white blood cells, decreased red blood cells

three changes that will affect the results of microscopic examination is the urine is not tested within 2 hours

bacterial growth

What is the main cause of changes in un-preserved urine

protein, bilirubin, leukocyte esterase, urobilinogen

four chemical parameters NOT affected by bacterial growth

it inhibits bacterial growth

Why is refrigeration the preferred way to preserve urinalysis specimens

pros: doesn't affect chemical tests, prevents bacterial growth

cons: precipitates amorphous phosphates and urates (dissolved stuff becomes un-dissolved; clarity decreases)

Pros and cons of refrigeration as a preservation method

pros: prevents bacterial growth

cons: interferes with drug analyses, affects pH, hormone analyses

Pros and cons of boric acid as a preservation method

pros: preserves sediment well

cons: affects chemical tests

Pros and cons of formalin as a preservation method

pros: good for drug tests

cons: inhibits reagent strips for glucose, blood, leukocytes

Pros and cons of sodium flouride as a preservation method

pros: convenient

cons: might affect tests; have to read chemical content to find out

Pros and cons of commercial preservative tablets as a preservation method

routine screening

What are random specimens used for?

routine screening, orthostatic protein confirmations, urine pregnancy tests

What are first morning specimens used for?

quantitative chemical tests

What are 24 hour timed specimens used for?

bacterial cultures

What are catheterized specimens used for?

bacterial cultures, routine screenings

What are mid-stream clean catch specimens used for?

bladder urine for bacterial culture, cytology; usually pediatrics

What are suprapubic aspiration specimens used for?

prostate infection

What are prostatic specimens used for?

First morning; more concentrated

What is specimen of choice for routine analysis? Why?

falsely elevated

If a patient fails to begin 24-hour urine collection with an empty bladder, how will it affect results?

catheterized, suprapubic aspiration, mid-stream clean catch

3 types of specimens suitable to diagnose bladder infection

results must withstand legal scrutiny

Why is chain of custody so important?

Reflectance photometry

Principle of automated reagent strip readers

to standardize readings; improve productivity, efficiency, accuracy, precision; removes human error

Why is reflectance photometry used in urinalysis analyzers?

barcodes

How do semi-automated and fully automated urine chemistry analyzers handle specimen ID?

fully automated

Which types of urine chemistry analyzer are capable of microscopic analysis?

LIS

results reported by urine chemistry analyzers are sent to

fluid intake, exercise, ADH (anti-diuretic hormone)

What factors determine urine volume?

Less than 400 mL/24 hours

What volume is associated with oliguria?

Adults: More than 2500 mL/24 hours

Pediatric: More than 2.5-3 mL/kg

What volume is associated with polyuria?

1200-1800 mL/day

What volume of urine is considered normal for an adult (per day)?

water

Urine is 95%

test temperature within four minutes; 32.5-37.7 degrees C

Describe the proper procedure for testing temperature of urine specimen

5.5-7

pH of urine

Leukocyte, nitrite, protein, blood, glucose, ketone, bilirubin, urobiligen, pH, specific gravity, creatinine

What chemicals are analyzed by semi-automated and fully automated urine chemistry analyzers?