108 final

State two characteristics of urine that make it an ideal laboratory specimen

Readily available and easy to test

Inexpensive and can show many metabolic functions

List three major organic chemical constituents of urine

Urea

Creatine
Uric acid

List three major inorganic chemical constituents of urine

Chloride

Sodium
Potassium

Describe a method for determining whether a questionable fluid is urine

Will contain urea and creatine High amounts of sodium and chloride

Define Oliguria and give a condition associated with it

A decrease in urine output

Dehydration

Define Polyuria and give a condition associated with it

An increase in urine output

Diabetes

Define Anuria and give a condition associated with it

Cessation of urine flow

Kidney damage

Define Nocturia and give a condition associated with it

An increase in the nocturnal excretion of urine

Age

Pregnancy
Enlarged prostate

Define Polydipsia and give a condition associated with it

Increased ingestion of water

Diabetes

A patient presenting with polyuria, nocturia, polydipsia, and a high urine specific gravity is exhibiting symptoms of what disorder?

Diabetes Mellitus

Describe the characteristics of the recommended urine specimen containers

Clear

Leakproof container with screw top lid
Capable of holding at least 50 ml

Why are disposable containers with a capacity of 50 mL recommended for the collection of specimens for routine urinalysis?

Allows enough sample for tests to be run

State four possible reasons why a laboratory would reject a urine specimen.

Improper labeling

Insufficient quantity
Improper transportation
Doesn't match Req forms

What error in specimen labeling could cause the improper reporting of two urine specimen results?

Mixing of specimens

Improper testing done

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

Odor

Nitrite
pH

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

Increased bacteria growth

Breakdown of urea to ammonia
Red/White blood cells break down

What is the primary cause of the changes that take place in unpreserved urine?

Bacteria

Name four chemical parameters not affected by bacteria

Protein

Bilirubin
Leukocyte Esterase
Urobilinogen

Briefly discuss five methods for preserving urine specimens, including their advantages and disadvantages

Refrigeration: Doesn't interfere with tests Precipitates Amorphous Phosphates and Amorphous Urates

Acids: Prevents bacterial growth and metabolizing
Interferes with drug and hormone analysis
Formalin (Formaldehyde): Excellent specimen preservation Acts as a reducing agent and interferes with Glucose, Blood, and LE testing
Sodium Fluoride: Good for drug analysis
Inhibits reagent strip testing for Glucose, Blood, and LE
Preservation tablets: Controlled concentration
Variety of effects on tests

Why is refrigeration the method of choice for preserving routine urinalysis specimens?

Doesn't interfere with chemical tests

Inhibits bacteria growth for 72 days

What chemical can be used to preserve a specimen for a culture and a routine urinalysis? What urinalysis parameter is affected?

Boric acid

Interferes with analysis of drugs and hormones
Only affects pH

What is the purpose of the following type of urine collection method: Random

Routine screening

What is the purpose of the following type of urine collection method: First Morning

Routine screening

Pregnancy test
Orthostatic protein

What is the purpose of the following type of urine collection method: 24-hour (Timed)

Quantitative chemical tests

What is the purpose of the following type of urine collection method: Cathiterized

Bacterial culture

What is the purpose of the following type of urine collection method: Mid-Stream Clean Catch

Routine screening

Bacterial culture

What is the purpose of the following type of urine collection method: Suprapubic Aspiration

Bacterial culture

Cytology

What is the purpose of the following type of urine collection method: Prostatic Specimen

Prostatic infection

List the three types of Prostatic Specimen collection

3 - glass

4 - glass
Pre & Postmassage Test

What is the specimen of choice for routine urinalysis? Why?

First morning

More concentrated

Will failure to begin a 24-hour urine collection with an empty bladder cause the results to be falsely elevated or decreased?

Falsely elevated

Name three types of urine specimens that would be acceptable for culture to diagnose a bladder infection

Catheter

Mid-Stream Clean Catch
Suprapubic Aspiration

Why is the chain of custody (COC) form an essential part of urine collections for drug analysis?

To hold up in court Withstand legal scrutiny
To ensure proper labeling and identification of specimen

What is the principle of Reflectance Photometry?

Beer's Law

How is Beer's Law used in Urinalysis Analyzers?

Standardizes it

Define: Filtration

The process where kidneys filter out the excess waste products from the blood

Define: Reabsorption

To take back into the blood that which previously was filtered out

Define: Secretion

Waste ions and hydrogen ions pass from the capillaries in to the renal tube

How much % of blood flows from the heart and then how much flows through the kidneys/min?

25%

1200 mL/min

Describe the difference in blood flow between the afferent and efferent arteriole

Afferent: Blood flows in

Efferent: Blood flows out

How much whole blood flows through the kidneys per min?

1200 mL/min

How much plasma flows through the kidneys per min?

600 mL/min

Why would the body surface area cause a difference in the laboratory filter tests?

Smaller people have less surface area and vice versa

What is the non-selective filtration of Bowman's space based upon?

Size

Charge

What other three factors influence filtration in the Glomerulus?

Hydrostatic pressure

Oncotic pressure
RAAS

What are the three cellular layers of the Glomerulus?

Capillary wall

Basement membrane
Bowman's Capsule

What is the "shield of negativity" in the glomerulus and how does it affect filtration?

Repels molecules with a negative charge

Explain the effect Renin has on renal blood flow

Regulates the blood flow to and within the glomerulus

What is the only difference between plasma and ultrafiltrate from glomerulus?

The absence of plasma proteins, protein bound substances, and cells

When does reabsorption of ultrafiltrate begin?

When it enters the Proximal Convoluted Tube

Differentiate between active transport and passive transport in tubular reabsorption.

Active transportation requires carrier proteins and cellular energy

In renal reabsorption or concentration, which substances are reabsorbed in passive transport and give the location in the tubules.

Water: Proximal Convoluted Tubule

Descending Loop of Henle
Collecting Duct
Urea: Proximal Convoluted Tubule
Ascending Loop of Henle
Sodium: Ascending Loop of Henle

In renal reabsorption or concentration, which substances are reabsorbed in active transport and give the location in the tubules.

Glucose, Amino Acids, Salts: Proximal Convoluted Tubule

Chloride: Ascending loop of Henle
Sodium: Proximal Convoluted Tubule
Distal Convoluted Tubule

What is the term used when plasma concentration of a substance that is normally reabsorbed reaches an abnormally high level and then spills into the urine and give an example of a substance where this occurs.

Renal threshold Glucose

Concentration of the plasma ultrafiltrate mainly takes place where in the nephron?

Loops of Henle

Describe the concentration in both loops of Henle

Sodium and Chloride ae reabsorbed in the Ascending Loop

Water is removed in the Descending Loop

What is name of hormone that controls Sodium reabsorption?

Aldosterone

What is the relationship of Aldosterone to the RAAS System?

Released by Renin

Raises plasma sodium content

Where does the final concentration of filtrate take place in renal system?

Collecting Duct

What is the primary goal of Antidiuretic Hormone (ADH)?

Water retention

List the common normal reportable urine colors

Clear

Straw (Pale yellow)
Yellow
Dark yellow

List the common abnormal reportable urine colors.

Dark yellow

Amber/Orange
Red/Pink/Brown
Brown/Black
Blue/Green

Discuss the relationship of urochrome to normal urine color.

Pigmented yellow Excreted constantly and is a good indicator of thyroid disorders, fasting, and hydration

What is the relationship of normal urine color to concentration of urine?

The more hydrated one is the lighter the color and the lower the concentration

Discuss the significance of phenazopyridine in a urine specimen and what color the urine might appear

Causes a thick, yellow-orange pigment in the specimen with a yellow foam

State how the presence of bilirubin in a specimen may be suspected.

Yellow foam produced when shaken

State how the presence of biliverdin in a specimen may be suspected.

Produces a yellow-green urine when photooxidized form bilirubin

State how the presence of uroerythrin in a specimen may be suspected.

Produces a pink color

Most evident in refrigerated specimens due to the precipitation of amorphous urates

State how the presence of urobilin in a specimen may be suspected.

Produces an orange-brown color

A product of the oxidation of urobilinogen

State a pathological cause of yellow urine foam and white urine foam

Yellow: Bilirubin present

Phenazopyridine present
White: Normal urine

Discuss the significance of cloudy, red urine and clear, red urine.

Cloudy: RBCs present

Clear: Hemoglobin/Myoglobin present

Under what conditions will a port-wine urine color be observed in a urine specimen

Oxidation of Porphobilinogen to Porphyrias

Name two pathologic causes of black or brown urine.

Hemogentistic acid

Melanina

Why might a brown urine have a positive chemical test result for blood?

Glomerular bleeding resulting from the conversion oh Hemaglobin to Methemoglobin

What test result is warranted before considering if a brown-black urine may contain melanin or homogentisic acid

A negative test for blood

Name a pathological cause and a nonpathological cause of blue or green urine.

Pathological: Urinary bacterial infections

Intestinal bacterial infections
Nonpathological: B vitamins

State the clinical significance of urine clarity

Usually clear

May indicate a pathological condition if turbid

List the common terminology used to report clarity

Clear

Hazy
Cloudy
Turbid
Milky

Describe the appearance and discuss the significance of amorphous phosphates and amorphous urates in freshly voided urine.

Amorphous Phosphates: white cloudiness in alkaline urine

Amorphous Urates: pink cloudiness in acidic urine

Differentiate between the appearance of amorphous phosphates and urates in a refrigerated urine specimen. What chemical test is critical to the differentiation?

Phosphates are white

Urates are pink
pH due to each appearing in different types of urine

In what circumstance might a sediment be slightly warmed before microscopic examination?

Amorphous urates

List three pathologic causes of cloudy urine.

RBCs

WBCs
Bacteria

List four nonpathological causes of cloudy urine.

Amorphous phosphates or urates

Radiological contrast media
Mucus
Squamos epithelial cells

How will urine specimen collection using the midstream clean-catch method affect urine clarity?

Typically clear

When should a microscopic examination be performed on a clear urine specimen?

Clarity and chemical tests come back positive for RBCs, WBCs, bacteria, and protein

Define specific gravity and tell why this measurement can be significant in the routine analysis

The density of a solution compared to the density of distilled water

Determines if the sample is concentrated enough to be used

Describe the principles of the refractometer for determining specific gravity.

Determines the concentration of dissolved particles in a specimen by measuring the refractive index

Describe the principles of the reagent strip for determining specific gravity.

Based ion a change in pKa of a polyelectrolyte in an alkaline medium

Describe the principles of the osmolality for determining specific gravity.

Changed in the colligative properties by particle number

Can a cloudy urine specimen have a low specific gravity? Why or why not?

Yes

Substances not dissolved in the urine don't contribute to SG

Name two nonpathogenic causes of abnormally high specific gravity readings using a refractometer

Glucose

Protein

What conclusion can be drawn from a specimen that has a SG of 1.001?

Distilled water

The specific gravity of a first morning specimen containing 2 g of protein and 2 g of glucose is 1.023, measured by refractometer. Does this indicate normal concentrating ability? Why or why not?

Yes

High protein and glucose can throw off a refractometer and must be accounted for

What would explain the high specific gravity of urine specimens from the following patients: A patient who has just returned from radiology.

Radiographic contrast media

What would explain the high specific gravity of urine specimens from the following patients: A patient who has recently been treated for a severe hemorrhage (low Blood Pressure)

Dextran or high molecule IV fluids

Describe the advantages of measuring specific gravity using a reagent strip and osmolality.

Accounts for any excess of glucose and protein

State possible causes of abnormal urine odor

UTIs

Ketones
Maple Syrup disease
Phenylketonuria

What are reagent strips?

Strips that consist of chemical-impregnated absorbent pads

What are some advantages in using in the Routine Urinalysis test?

Provide simple, rapid means for performing routine chemical tests on urine

Explain how chemical reactions are interpreted on reagent strips

Compare the color produced on the pad within time frame with a chart supplied by manufacturer