Body Fluids Exam 1 Flashcards
Kidney anatomy:
Where blood enters the glomerulus
Afferent arteriole
Kidney anatomy:
Where unfiltered blood exits the glomerulus
Efferent arteriole
Kidney anatomy:
This part of the nephron is where water and electrolyte exchange takes place
Loop of Henle
Kidney anatomy:
The microscopic structural and functional unit of the kidney
Nephron
Kidney anatomy:
Receives/filters blood
Glomerulus
Kidney anatomy:
Location of glomerulus
Bowman’s Capsule
Kidney anatomy:
Primary site of reabsorption of water and essential substances
Proximal convoluted tubule
Kidney anatomy:
Where concentration of urine begins in the nephron
Distal convoluted tubule
Kidney anatomy:
Where final concentration and secretion takes place in the nephron
Collecting ducts
Kidney anatomy:
Average amount of blood flowing through kidneys
1200 mL/min
Kidney anatomy:
Renal blood pressure/blood volume is controlled by
Renin-angiotensin-aldosterone system (RAA)
Kidney anatomy:
The glomerulus filters substances of what molecular weight?
< 70,000
Kidney anatomy:
The glomerulus creates a ______ free ultra-filtrate
Protein free
Kidney anatomy:
The glomerulus creates a protein free ultra-filtrate at what rate?
120 mL/min
Kidney anatomy:
What is not found in the glomerular ultra-filtrate?
Proteins
Protein-bound elements
Cells
Anything with a larger molecular weight than 70,000
Kidney anatomy:
What is the glomerular ultra-filtrate of 120 mL/min called?
GFR
Glomerular Filtration Rate
This is where the return of water and essential substances back into blood occurs
Proximal tubule of nephron
Where is renin released from?
Kidneys
What causes the RAA system to “turn on”
Decrease in Renal Blood Pressure/Volume
Where does aldosterone come from?
Adrenal glands
Glomerular Filtration Rate
120 mL/min
Repels molecules with a positive charge (such as proteins)
Shield of negativity
What makes it through glomerular filtration?
Glucose
Electrolytes
Water
What substance is reabsorbed in response to aldosterone?
Sodium
What causes sodium to be reabsorbed?
Aldosterone
Definition:
Substances go from tubule back into the bloodstream
Reabsorption
What is reabsorbed in to the bloodstream?
Mostly water
Glucose
Amino Acids
Other Essential electrolytes
Where does 60-85% of reabsorption occur in the nephron?
Proximal Convoluted Tubules
Definition:
Plasma concentration of a substance at which reabsorption stops and the substance begins to appear in urine
Renal Threshold
What is the range for Glucose Renal Threshold?
160 - 180 mg/dL
Removes large, unfilterable waste products from the blood in to the tubular filtrate
Tubular secretion
Tubular secretion excretes these for maintenance of blood acid-base balance
Hydrogen ions
Where does the final reabsorption of water occur in the nephron?
Distal Convoluted Tubules and the Collecting Ducts
Concentration is controlled by what hormone?
Anti-Diuretic Hormone (ADH)
AKA
Vasopressin
Another name for ADH
Vasopressin
What triggers ADH?
An increase in plasma concentration of sodium
Functions of kidneys (5)
Removal of waste products
Retention of nutrients and essential compounds
Acid-base balance
Water balance
Hormone synthesis (renin, erythropoiten, vitamin D)
Composition of urine
Urea (protein metabolism)
Uric acid (purine metabolism)
Creatinine (muscle cell breakdown)
Cl-, Na+, K+, H+ (electrolytes)
Few formed elements (squamous epis, possible crystals, bacteria, casts, WBCs, RBCs)
Average output of urine
600 - 2000 mL/24 hrs
Definition:
Decreased output of urine
Oliguria
Definition:
No output of urine
Anuria
Definition:
Increased output of urine
Polyuria
Definition:
Painful flow of urine
Dysuria
Definition:
Increased output of urine at night
Nocturia
What will average output of urine depend on?
State of hydration
Possible causes of oliguria
(3)
Dehydration
Diabetes
UTI
Possible causes of anuria
(3)
Kidney failure
Kidney damage
Decreased blood flow
Possible causes of polyuria
(4)
Diabetes insipidus (Na+ issue)
Diabetes mellitus (glucose issue)
Caffeine
Alcohol
Possible causes of dysuria
(5)
UTI
Kidney stones
Enlarged prostate
STD/STI
Yeast infection
Possible causes for nocturia
(2)
Pregnancy
Elderly
Rate at which blood enters the kidneys
1200 mL/min
Rate at which the kidneys filter blood
120 mL/min
Hormone that controls final reabsorption of water
Anti-diuretic hormone (ADH)
AKA
Vasopressin
Term used to describe the point where reabsorption of a substance stops
Renal threshold
Included in physical examination of urine
(3)
Color
Clarity
Specific gravity
Normal color of urine is due to
Urochrome
Cause of clear, yellow urine
Normal
Cause of colorless, pale, or straw colored urine
Diluted urine
Diabetes
Causes of dark yellow or amber colored urine
Concentrated urine
Dehydration
Cause of amber/brownish-orange urine
Icteric- presence of bilirubin
Cause of orange colored urine
UTI drugs (pyridium)
UTI drug that is known for causing urine to turn orange
Pyridium
Cause of blue or green colored urine
Drugs (such as birth control)
or Dyes
Cause of brown urine
Old bloody urine
Cause for red, cloudy urine
Intact RBCs (hematuria)
Cause for red, clear urine
Hemoglobin (hemoglobinuria)
Myoglobin (myoglobinuria)
Cause for red-purple urine
Porphyrins
Cause for black urine
Melanin
or
Homogentisic acid
What affects the color of urine? (4)
Metabolism
Ingested materials
Diseases
Physical activity
Clarity of urine:
Transparent; no visible particulates
Clear
Clarity of urine:
Few particulates
Hazy
Clarity of urine:
Print is blurred through the urine
Cloudy
Clarity of urine:
Print not seen
Turbid
Clarity of urine:
May precipitate or clot
Milky
Causes for milky urine
Increased lipids
Increased proteins
Nonpathologic causes of hazy, slightly cloudy, cloudy, or turbid urine
(7)
Mucus
Talc
Cream
Fecal contamination
Sperm
Squamous epithelial cells
Certian crystals (ammonium biurate, triple phosphate uric)
Pathologic causes for hazy, slightly cloudy, cloudy, or turbid urine
(8)
RBCs
WBCs (infection, STD/STI)
Crystals (bilirubin, leucine)
Bacteria, yeast, Trichomonas (UTI, genital contamination)
Renal epithelial cells (deterioration in kidneys)
Lipids (milky urine)
Definition:
A measure of dissolved substances present in a solution. Primarily reflects the patient’s state of hydration
Specific Gravity
Term used for the presence of intact red cells in the urine
Hematuria
Term used for presence of lysed red cells or free hemoglobin in the urine
Hemoglobinuria
Assesses the kidney’s ability to reabsorb water
Specific Gravity
What influences specific gravity?
Size and number of particles
Normal urine specific gravity
1.003 - 1.035
TRUE or FALSE
Urine can have a specific gravity of 1.000
FALSE
Pure water has this SG
Specific gravity of glomerular filtrate
1.010
What does having a fixed SG of 1.010 from multiple samples indicate?
Renal dysfunction
Correlation between volume of urine and specific gravity
As volume increases, specific gravity decreases (hydrated)
As volume decreases, specific gravity increases (dehydrated)
TRUE or FALSE
Diseased kidneys lose the ability to concentrate/dilute urine causing the specific gravity to become fixed at 1.035
FALSE
Specific gravity becomes fixed at 1.010 due to glomerular filtration working but nothing else.
3 ways to measure specific gravity (SG)
Dipstick
Harmonic oscillation
Refractometer
Method of measuring Specific Gravity:
The frequency of sound waves will change in proportion to the density
Harmonic oscillation densitometry
Compares the velocity of light in air with the velocity of light in a solution
Refractive index
Method of measuring Specific Gravity:
The density of dissolved particles present in the sample will determine the angle at which light passes through a solution
Refractometer
What “fixed” SG value is associated with kidney problems?
1.010
Generally, as urine volume increases, specific gravity _______
Decreases
Steps to follow if SG is off the scale
Dilute 1:2
Rerun
Multiply result by dilution factor
Causes for Abnormal Specific Gravity Using a Refractometer
Low
(dilute or hypotonic)
Diabetes insipidus (impaired ADH, increased plasma Na+, Increased thirst)
High water intake
Causes for Abnormal Specific Gravity Using a Refractometer
High
(concentrated, hypertonic)
Protein
Diabetes mellitus (defective insulin, increased plasma/urine glucose)
Dehydration
Radiographic dyes
Some IV fluids
Causes for Abnormal Specific Gravity Using a Refractometer
Fixed 1.010
Renal disorder
This causes a vivd yellow foam
Bilirubin
This causes an abundant amount of white foam
Protein
TRUE or FALSE
A small amount of white foam is normal when urine is shaken
TRUE
Urine Odor:
Normal
Faintly aromatic
Urine odor:
Strong unpleasant ammonia-like odor, foul
Bacterial infection
Urine Odor:
Sweet or fruity due to the presences of ketones
Diabetes
Urine Odor:
Syrup, sulfur, mousey
Metabolic defects
Automated method for chemical analysis of urine
Reflectance photometry
(As color increases, reflectance of light decreases)
TRUE or FALSE
Reagent strips should always be protected from moisture, light, heat, volatile chemicals, and should be refrigerated.
FALSE
Reagent strips should always be protected from moisture, light, heat, and volatile chemicals but should NOT be refrigerated.
Normal urine pH
4.5 - 8.0
Causes of acidic pH
(4)
H+
Ketones - due to starvatin or Type 1 Diabetes mellitus
Dehydration
Cranberry juice
Causes of alkaline pH
(2)
Certain UTIs (bacteria create ammonia)
Old urine (normal flora reproduce creating ammonia)
Principle for testing pH
Double indicator system
Are there any interfering factors for pH?
No
What is the best indicator of renal disease?
Protein
Normal result for protein in urine
Negative or Trace
What is the only protein detected by dipstick?
Albumin
Causes of Pre-renal proteinuria
Excessive blood protein levels
-Hemoglobin
-Myoglobin
-Bence Jones proteins
Functional causes of Renal proteinuria
(4)
-Seizures
-Fever
-Excessive stress/exercise
-Hypertension
Pathologic causes of Renal proteinuria
(3)
-Glomerular
-Tubular
-Interstitial
Causes of Post-renal proteinuria
(3)
Disease of renal pelvis onwards
-Infection
-Urolithiasis
-Neoplasia
Protein associated with Multiple Myeloma
Bence Jones proteins
Glomerular disorders or damage by toxins will cause what type of proteinuria?
Renal proteinuria
Pressure on the renal vein causing a positive protein result when standing upright but a negative protein result after lying down
Orthostatic or Postural proteinuria
Principle for testing protein
Protein error of indicators
Interfering factors for a false positive protein
Alkaline urine - check pH
Interfering factors for a false negative protein result
Protein other than albumin (Ex. BJ protein)
Microalbuminuria (not enough albumin to trigger threshold)
Confirmatory test for positive protein dipstick
Sulfosalicylic Acid Precipitation (SSA)
Causes of false positive SSA result
Radiographic Dyes
Drug Crystals
Most frequent chemical test performed on urine
Glucose
Normal Renal threshold for glucose
160 - 180 mg/dL
When the blood level of gluvose becomes so elevated that tubular reabsorption can’t keep up, glucose will appear in urine.
Renal Threshold
Major cause of glucose in urine
Diabetes
Term for glucose in urine
Glycosuria
AKA
Glucosuria
Principle of the reaction for glucose
Double sequential enzyme specific for glucose
Interfering factors for a false negative glucose on urine dipstick
Acorbic acid (vitamin C)
High SG
Unpreserved specimens (glycolysis from bacteria and normal flora digesting glucose until its gone or too low)
Confirmation test for positive dipstick glucose
Copper Reduction Test
AKA
Clinitest
TRUE or FALSE
The Copper Reduction Test reacts with ALL reducing sugars
TRUE
Reducing sugars convert copper sulfate to cuprous oxide in the presence of heat and alkali
Copper Reduction Test
AKA
Clinitest
Positive Glucose dipstick
+
Positive Clinitest
=
Glucose present
Trace - 1+ Glucose Dipstick
+
Negative Clinitest
=
Small glucose
2+ - 4+ Glucose dipstick result
+
Negative Clinitest result
=
Interference or testing error
Negative Glucose dipstick
+
Positive Clinitest result
=
Other reducing sugars
*Galactose* - congenital enzyme defect; failure to thrive, retardation,
screen kids < 2 years old
3 by-products of fat metabolism
Ketones
What are the by-products of fat metabolism?
(3)
-Acetone
-Acetoacetic acid
-Beta-hydroxybutyric acid
Clinical significance of ketones
-Diabetes mellitus
-Starvation
-Carb-free diets
-Vomiting
-Malabsorption
Term for ketones in urine
Ketonuria
What does Diabetes mellitus with insufficient insulin control cause?
(5)
-Glucosuria
-Ketonuria
-Acid pH
-Positive serum glucose/ketone
-Risk of diabetic keto-acidosis (DKA)
Principle of the Reaction for ketones
Sodium nitroprusside reaction
Interfering factors for a false negative ketone dipstick result
-Evaporation
-Improper storage of specimen
Interfering factors for a false positive ketone dipstick
-Drugs
-Medication
-Dyes (radioactive)
Confirmatory test for ketones
Acetest
Test that is the best indicator for renal disease
Protein - testing for albumin, specifically
Test that will most likely be positive if a patient is starving
Ketones
Substance that can cause a false negative glucose result
Ascorbic acid
AKA
Vitamin C
3 causes for a dipstick to result as positive for blood
-Hematuria
-Hemoglobinuria
-Myoglobinuria
- Presence of intact red cells in urine
- Urine usually appears red and hazy or cloudy
- Sometimes not visible
- Trauma or injury; toxins; tumors
- Kidney stones
- Glomerulonephritis/ Pyelonephritis
- Menstruation
Hematuria
- Presence of free hemoglobin
- Urine appears clear, reddish-brown
- Intravascular hemolysis (transfusion reactions, hemolyic anemias, burns)
Hemoglobinuria
- Presence of muscle protein
- Appears clear, reddish-brown
- Muscle crush or muscle-wasting disease (rhabdomyolysis)
- AMI
- Strenuous exercise in an untrained person
- Confirmed with special testing
Myoglobinuria
Principle of reaction for blood on dipstick
Pseudoperoxidase activity of hemoglobin
Free hemoglobin or myoglobin will cause what type of reaction on the dipstick?
uniform color reaction
Intact red cells will cause what type of reaction on the dipstick?
Speckled pattern
Sensitive to as few as 5-10 cells/uL
Interfering factors for false positive blood result on dipstick
Menstrual contamination
Interfering factor for false negative for blood on dipstick
High SG (may crenate cells)
Degradation product of hemoglobin that is normally metabolized in the liver
Bilirubin
Causes a vivd yellow foam on urine
Bilirubin
What could cause direct (unconjugated) bilirubin in the urine?
Hepatitis
Cirrhosis and other liver disorders
Biliary obstruction (gallstones, tumor, etc)
Principle of reaction for bilirubin on dipstick
Diazo reaction
Interfering factor for false positive for bilirubin on dipstick
Pigments from dyes or drugs
Interfering factor for a false negative bilirubin dipstick result
Exposure to light
Confirmatory test for bilirubin
Ictotest
- Normal by-product of RBC degradation
- Formed from thereduction of bilirubin by bacterial enzymes in the intestines
- Excreted in both feces and urine
Urobilinogen
