Flashcards in Intro to Urinalysis II Deck (51):
In measuring specific gravity by reagent strip, when urine pH is > or equal to 7.0 add ______ to the strip reading if it is being read manually
Is there interference from glucose, protein, or radiographic dyes when measuring specific gravity by reagent strip?
What is the specific gravity of the filtrate as it leaves the glomerulus?
This term is used to describe urine with a specific gravity of 1.010
This term is used to describe urine with a specific gravity of <1.010
If a urine is constantly <1.010 (hyposthenuric) what does this represent?
the kidney's inability to concentrate urine, diabetes insipidus, renal disease
What does urine with a specific gravity constantly >1.010 represent?
adrenal insufficiency, congestive heart failure, hepatic disease, dehydration
What is the physiological limit of specific gravity?
1.040, could be due to radiographic dyes
Low fluid intake = _____ specific gravity
high fluid intake = ____ specific gravity
If the specific gravity is greater than 1.035 what should you do?
make a 1:2 dilution with distilled water and multiply all digits to the right of the decimal by your dilution factor
this is the measure of the concentration of dissolved particles in a solution expressed in osmoles of solute particles per kg of solvent
osmolality only measures dissolved particles, thus _____ and ______ are not measured
lipids and protein
Reference range for specific gravity
1.003 to 1.030
Reference Range for urine color
colorless to yellow
Reference Range for Urine volume
What does a specific gravity of 1.003 represent ?
Usually a diluted urine
What causes changes in urine volume in pathologic states?
solute diuresis in diabetes mellitus
What causes changes in urine volume in non-pathologic states?
fluid intake, vomiting, diarrhea, sweating, variation in secretion of ADH, water loss, medications, diuretic therapy, caffeine, alcohol
This term is used when describing urine output <400mL/24hrs; decreased volume is due to excess water loss
this is known as the cessation of urine flow
this is increased volume of urine at night, caused by renal failure
this is known as increased daily urine volume, caused by diabetes mellitus, diabetes insipidus, medications, diuretic therapy, caffeine, and alcohol
List the proper criteria for a good specimen (3 things)
1 proper patient ID (name, location, physician, collection date, collection time, test requested)
2 Fresh collection (should be tested within two hours after collection)
3 If testing delayed urine should be refrigerated
this technique requires no preparation; good for screening; not good for urine cultures
technique often used with random specimens; good for urine culture and routine analysis; noncompliance in collection technique; difficult for some patients to collect
clean catch midstream (CCMS)
specimen good for urine cultures and routine analysis; can enter the bladder or either of the ureters and provide information about each kidney independently; can cause UTIs; can cause discomfot in patients
involves collecting urine directly from the bladder by puncturing the abdominal wall with a needle and a syringe; usually performed for bacterial cultures (especially anaerobes); used on infants when specimen contamination is unavoidable; sterile but invasive
what testing Is a pediatric urine collection bag used for?
for screening purposes, not for urine culture because of contamination
This urine requires no preparation, can be collected anytime, used for routine screening and to detect disease processes, affected by variances in fluid intake and exercise
this urine is collected as soon as waking up, ideal for testing specimens that require concentration and incubation (nitrates, protein, bacteria), confimation of orthostatic proteinuria, formed elements more stable, cells have better morphology, more epithlial cells for cytology studies
First morning urine
What is a disadvantage of a first morning urine?
additional crystals may precipitate upon cooling, specimen must be preserved if not tested within 2 hours
In this type of collection the goal is to eliminate metabolites from food ingested prior to the beginning of the test, often used for glucose monitoring for patients with diabetes mellitus or gestational diabetes
This type of urine requires the patient to void immediately before eating and the collect urine 2 hours post eating; used for diabetes mellitus monitoring; also known as a fractional collection
2 hour postprandial
this type of urine collection is used because of circadian and diurnal variations in hormones, proteins, glomerular filtration rates, exercise, hydration, etc; usually 12 or 24 hour collection; preservative is usually in the bottle before patient takes it home
When measuring a urine's specific gravity using a reagent dipstick, are you required to correct for elevated urine glucose?
NO, the reagent strip is not affected by elevated glucose levels
pH ________ (increases/decreases) due to decomposition of urea to ammonia and loss of CO2 as a specimen is allowed to sit out, unpreserved
glucose is _______ (increased/decreased) due to bacterial consumption as a urine is allowed to sit.
Ketones ______ (increase/decrease) due to bacterial action and will vaporize as a urine is allowed to sit
Bilirubin _____ (increases/decreases) due to photo-oxidation as it sets out
Urobilinogen _______ (increases/decreases) due to oxidation to urobilin
Nitrites _______ (increase/decrease) due to bacterial production
If urines are left unpreserved what 3 structures are affected?
RBCs and WBCs degrade, Casts degrade, and bacteria increase
What is the most common method of preservation?
refrigeration at 4-6*C, REMEMBER allow urine to reach room temp before testing
What is a disadvantage of refrigerating urine?
precipitation of amorphous urates and phosphate crystals that interfere with microscopic analysis
Culture of a refrigerated specimen is preferred in ___ Hours but will be accepted up to ___ Hours
8 hours, 24 hours
Culture on an unrefrigerated specimen must be performed within ___ Hours post collection
commonly used preservative for 24 hour urines, preserves protein and formed elements, bacteriostatic/not bactericidal so can be used for culture, precipitates out crystals, decreases pH, interferes with drug and hormone analysis
preservative that is an excellent cell preservative, interferes with glucose, blood, leukocyte esterase, and copper reduction testing (clinitest)
preserves sediments such as cells and casts