normal urine is how much water?
96%
normal urine is how much solutes?
4%
solute variations occur in urine due to?
diet, activity, metabolism, endocrine function, body position
Organic solutes found in urine
urea, creatinine, uric acid
inorganic solutes found in urine
chloride, sodium, potassium
formed elements in urine may indicate
disease
inorganic solutes in urine are affected by
dietary intake
urine volume is determined by
body's state of hydration
What determines body's state of hydration
fluid intake, non renal fluid loss, ADH variations, excretion of large amounts of dissolved solids
Usual daily volume of urine
1200-1500 mL
normal range of urine
600-2000 mL
Oliguria
decreased urine output
what qualifies as oliguria in adults
<400 mL/day
what can cause oliguria?
vomiting, diarrhea, perspiration, severe burns
Anuria
cessation of urine flow
what can cause anuria?
severe kidney damage, decreased renal blood flow
Nocturia
increased urine excretion at night
polyuria
increased urine output
what qualifies as polyuria in adults?
>2.5 L/day
what can cause polyuria?
diabetes mellitus or insipidus, diuretics, caffeine or alcohol
Isothenuria
inability of kidneys to change specific gravity of plasma ultrafiltrate
SG of urine
1.010
Polyuria in diabetes mellitus
increased volume caused by need to exert the excess glucose not reabsorbed from the ultrafiltrate
which patients exhibit polydipsia?
diabetes mellitus, diabetes insipidus
polyuria in diabetes insipidus
decreased production or function of ADH causing decreased reabsorption of water from ultrafiltrate
specific gravity in diabetes mellitus
high
specific gravity in diabetes insipidus
low
Specimen collection for polyuria
disposable wide-mouthed flat-bottomed containers, clear containers, at least 50 mL capacity, adhesive bags for pediatrics, large plastic containers
what should you wear when dealing with urine?
gloves
When hemoglobin oxidizes into methemoglobin in urine, what color will form?
brown
Specimen labeling must include
patient's name, unique ID number, date and time of specimen collection, date of birth, ordering physician
the label should be placed on what?
container
what is a requisition form?
the order for the specimen collection
Specimen is rejected for:
unlabeled containers, non-matching labels and requisitions, contaminated specimens, contamination on exterior of container, insufficient quantity, delayed or improper transport
Specimen integrity
tested within 2 hours of collection, delayed testing requires refrigeration or chemical preservatives
most problems with specimen are caused by
bacterial growth
routine preservation by refrigeration
required for culture specimens, causes increase in specific gravity and precipitation of amorphous crystals
refrigerated specimen procedure prior to chemical testing
return to room temperature
chemical preservatives for specimen preservation
commercial transport tubes that must be compatible with chemical testing
what is the ideal preservative for specimen preservation
bactericidal, inhibit urease and preserve formed elements
Metabolic state of patient
diet, medications
what is the most common type of collection?
random specimen
when can a random specimen be collected?
at any time
What does a random specimen screen for?
obvious abnormalities
What may alter a random specimen?
dietary intake and activity
What is the ideal screening specimen?
first morning specimen
Why is first morning specimen ideal?
more concentrated than a random specimen
what is first morning specimen used for?
orthostatic protein confirmation, urine pregnancy tests
When should a first morning specimen be delivered to the lab?
within 2 hours
Fasting specimen is collected when?
second specimen voided after fasting
Why is fasting specimen the second specimen voided?
to prevent contamination from metabolites from evening meal
What is fasting specimen recommended for?
glucose monitoring
2-hour postprandial test
patient voids before eating routine meal, eats meal, waits 2 hours after finish meal, collects specimen after 2 hours
what is the urine in the 2-hour postprandial test used for?
glucose, insulin therapy monitoring
24-hour (timed) specimen
required for quantitative results and necessary for measuring substances
What does 24-hour timed specimen demonstrate?
diurnal variation that differs with am and pm, substances that vary with meals, activity, and body metabolism
What is required for accurate results in a timed specimen?
accurate timing
If you perform a urine dipstick and get a positive result on the protein pad, what does this indicate?
may have renal disease
Timed specimen principle is what?
collection must begin and end with an empty bladder
Timed specimen timing schedule
patient wakes up and voids - discard urine, patient begins collecting urine at next void, at the same time the next day, the patient voids and adds to the container to finish off collection
calculation for units per 24 hours includes
volume in mL of urine collected
Handling of timed specimens
thoroughly mix specimen and measure, save a large enough aliquot to test and to repeat test, keep specimen on ice or refrigerated during collection, use appropriate and nontoxic preservatives
Catheterized specimens
sterile specimen collected from bladder with a catheter through urethra
what is catheterized specimen most commonly used for?
culture and sensitivity
Midstream clean-catch specimen is an alternative to what?
catheterized specimen
midstream clean-catch specimen provides more or less contamination than routine collection?
less
Instructions for midstream clean-catch
wash hands, clean genitalia with supplied cleaner, void into toilet, then into container, then finish in toilet
What should not be touched in a midstream clean-catch specimen collection?
the inside of the container
Suprapubic aspiration
external needle aspiration from the bladder that is completely free of contamination for culture and cytology
Pediatric specimens
soft, clear plastic bags with hypoallergenic tape applied to genital area
Drug specimen collection requires
proper collection, labeling and handling must be documented
Chain of custody for drug specimen collection
documentation from the time of specimen collection until the time of recipes of laboratory results
Points to consider for drug specimen collection
photo ID of urine donor or ID of employer, no unauthorized access to specimen, no adulteration/substitution/dilution of specimen
Witnessed versus unwitnessed collection is determined by
individual ordering the test
The specimen is handed over to the collector
immediately
adulteration tests
temperature taken within 4 minutes must be within 32-37C and color of urine- if not normal, report temperature and recollect sample