Body Fluids Exam 1

What is the principle of operation of most semi-automated urine dipstick readers?

Reflectance photometry

What is the normal pH range of urine?

4.5-8.0

How might starvation or vomiting affect a urine's pH? What is present in the urine to cause this change?

It may become more acidic due to the presence of ketones

How might a UTI or an old urine affect urine pH and why?

The pH might rise due to the production of bacterial waste products

What substance, when detected in urine, is most indicative of renal disease?

Protein

What major protein is detected up by a urine dipstick?

Albumin

What are Bence Jones proteins, and in what condition are they often present?

Free kappa or lambda light chains, common in multiple myeloma

What are small amounts of albumin in urine which might not be picked up by the dipstick called?

Microalbumin

What is the significance of a positive test for microalbumin?

Warning sign of renal problems, notably in diabetics

What is another tern for postural proteinuria?

Orthostatic

What are the typical protein findings in someone with postural proteinuria?

First urine upon rising: protein negative;
Urine after being upright: protein positive

How will a highly alkaline urine affect the protein dipstick?

Falsely elevate

Other than proteins, what 2 substances can cause an SSA test to be positive?

Drugs & dyes

At what plasma level will glucose begin to appear in urine?

160 mg/dL

What 2 conditions or substances can cause a falsely decreased glucose dipstick reaction?

Ascorbic acid (Vit. C) & unpreserved samples (glycolysis)

On what population of patients might a Clinitest (copper reduction test) be ordered?

2-3 yrs or younger

A dipstick is 1+ positive for glucose, however the Clinitest is negative. With is most likely causing this combination of results?

Low levels of glucose

A dipstick is negative for glucose but the urine reacts strongly reactive with the Clinitest. What might be causing these results?

Galactose or another sugar besides glucose

What are 4 conditions that can cause the urine to be ketone positive?

Uncontrolled diabetes, starvation, prolonged vomiting or diarrhea, some diets

Why does leaving the cap off of a urine container cause falsely decreased ketone results?

Ketones will evaporate

What 3 things will cause a dipstick to be positive for blood?

Hemoglobin, myoglobin, and intact RBCs

What are 2 conditions that could cause the appearance of myoglobin in urine?

Heart attack or muscle injury

What 2 substances will cause the urine to appear clear and red/reddish-brown?

Hemoglobin & myoglobin

What type of bilirubin will filter through the glomerulus?

Conjugated (direct) bilirubin

Which urine chemical reacts with Diazo reagent?

Bilirubin

Where does bilirubin originate?

From the heme within RBCs

Which 2 urine chemicals are most sensitive to light exposure?

Bilirubin & urobilinogen

In what organ is urobilinogen formed?

Intestines

Is bilirubin or urobilinogen normally found in the the urine in small volumes?

Urobilinogen

What is the expected urine bilirubin and urobilinogen results in a case of bile duct obstruction?R

Bilirubin positive, urobilinogen negative

What is the expected urine bilirubin and urobilinogen results in a case of hemolytic anemia?

Bilirubin negative, urobilinogen positive

What do you see in a urine microscopic if the nitrate is positive?

Bacteria

Is a negative nitrite confirmation that bacteria are absent? Why or why not?

No, because not all bacteria produce nitrate

What 2 conditions are consistent with a positive nitrite result?

UTI & unpreserved urine

Other than nitrite, what other dipstick result is consistent with infection?

Leukocyte esterase

What is the term for the presence of WBCs in urine?

Pyuria

What characteristic of a substance will determine whether or not it will react with the SG portion of a dipstick?

Must be iconic in nature

What 3 substances will not react with the SG pad on a dipstick, but can be measured by refractive index?

Glucose, dyes, & urea

What type of white cells are seen in (non-bacterial) inflammation?

Lymphocytes

What WBCs do not react well with a dipstick?

Lymphocytes

What is the term for an infection within the kidney nephron?

Pyelonephritis

What is the term for a bladder infection?

Cystitis

What 2 conditions are most likely to cause the presence of bilirubin in urine?

Liver disease & bile duct obstruction

What would most likely be causing the dipstick to be strongly positive for glucose, but negative on the Clinitest?

Interfering substance or testing error

What metabolic process creates ketones?

Fat metabolism

What does speckling on the blood dipstick pad indicate?

Intact RBCs

What area of the nephron receives and filters blood?

Glomerulus within Bowman's capsule

Which part of the nephron is the primary site of reabsorption of essential substances?

Proximal convoluted tubule

What is the average amount of blood that flows through the kidneys each minute?

1200 mL/min

In response to a decreased blood pressure of blood volume, what hormone is secreted by the kidneys?

Renin

What type of arteriole feeds blood into the glomerulus?

Afferent

What type of arteriole feeds blood out of the glomerulus?

Efferent

What adrenal hormone is secreted upon stimulation by angiotensin?

Aldosterone

What analyte is reabsorbed under the influence of aldosterone?

Sodium

What is not normally allowed to filter through the glomerulus?

Cells, protein, & protein-bound substances

What is the normal average glomerular filtration rate?

120 mL/min

What is the term used to describe the level of a substance when it can no longer be absorbed by the renal tubules?

Renal threshold

What is the normal plasma level of glucose?

75-105 mg/dL

What is the normal renal threshold of glucose?

>160 mg/dL

What process allows unfilterable wastes to pass into the tubules for elimination?

Tubular secretion

The final reabsorption of water is directly under the influence of what hormone?

Antidiuretic hormone (Vasopressin)

What influences the secretion of ADH from the pituitary gland?

The concentration (osmolality) of the plasma

What triggers ADH release?

Sodium plasma increase

In what area of the nephron does the final concentration of urine occur?

Distal tubules/collecting ducts

What waste product is normally present in protein metabolism?

Urea

What waste product is normally present in muscle metabolism?

Creatinine

What waste product is normally present in purine metabolism?

Uric acid

What is the term for decreased urine output?

Oliguria

What is term for painful urination?

Dysuria

What is the term for no urine output?

Anuria

What is the cause of anuria?

Renal failure

What is the term for increased urine output?

Polyuria

What is the average normal output of urine in 24 hours?

1200 mL

What are 2 diseases that may cause a high volume, pale-looking urine?

Diabetes mellitus & diabetes insipidus

What is the most common cause of a dark yellow urine?

Dehydration

What would a urine containing bilirubin look like?

Brown/amber with yellow foam

What 2 substances will cause a clear red to reddish-brown urine?

Hemoglobin & myoglobin

What appearance will a urine that contains a lot of intact RBCs have?

Red & hazy/cloudy

What are causes of having intact RBCs in urine?

Glomerular disease, kidney/bladder trauma or infection, & menstrual contamination

Urine that turns brown-black upon standing might contain what 2 substances?

Melanin & homogentisic acid

A lot of white foam on a urine is a clue to the presence of what substance?

Protein

What appearance will a urine that contains certain porphyrins have?

Burgundy or port wine

Why must urine be mixed before determining color and clarity?

Cells & other substances may have settled to the bottom, giving the urine a clearer appearance

What are 3 insignificant causes of a hazy urine?

Presence of creams or powders, squamous epithelial cells, & certain crystals or sperm

What are significant causes of a hazy/cloudy urine?

RBCs, WBCs, certain crystals, fats, renal cells, bacteria, or other micro-organisms

What urine test is a reflection of the body's state of hydration?

Specific gravity

What is the normal range of urine specific gravity?

1.003-1.035

If a patient is severely dehydrated, would the SG be higher or lower?

Higher

What SG reading (when measured at various times) is consistent with the kidneys inability to concentrate urine?

1.010

What term describes the angle of light as it passes through a urine sample?

Refractive index

What property will increase the angle in refractive index?

Density

If a urine was diluted 1:4 and the SG read 1.012, what is the SG of the undiluted urine?

1.048 (.012 x 4)

What could cause an elevated refractive index?

Proteins, glucose, dehydration, dyes, or IV solutions

Renal anatomy

What process leads to the formation of bilirubin?

Red cell lysis

Renin-angiotensin-aldosterone system

Anti-diuretic hormone release

What gives urine its yellow color?

Urochrome

What gives urine an amber color?

Bilirubin

What gives urine an orange color?

Pyridium