Ex 41A
Urinalysis& Electrolytes
Urine
Definitionsspecific gravity
compares the relative weight of water to the weight of other elements
water = 1 (1ml of water=1g)
iron = 7.85 (in other words, iron is 7.85x more dense than water)
gold = 19.3
potassium = 0.85
would a pure potassium tablet float or sink in water?
pH
measure of H+ ions vs. OH- ions
pH 1 = very acid (many H+ ions)
pH 14 = very alkaline (many OH- ions)
pH 7 = neutral
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Urinalysis
Dipstick
color changes when urine is placed on a test strip.
each pad reacts with a color change to different chemicals
squares vary depending on manufacturer so be careful
Leukocytes, nitrite, urobilinogen, protein, pH, blood, ketones, bilirubin, glucose
Urinalysis: Normal
normal range comments
color clear to yellow •color due to urochrome, a metabolite
of hemoglobin breakdown
•urine is usually darker when urine
output is low
odor slight musky to asparagus
•the subway smell comes from bacteria
breaking down urea to ammonia
specific gravity 1.001-1.030 •higher when urine output is low
(dehydration)
•if > 1.035 possible diabetes or
radioopaque dye
sodium —— •high concentration with dehydration
pH 4.5-8.0 (ave. 6.0) •acid with high protein consumption
•alkaline with high flora consumption
wastes urea, uric acid, creatinine
•urea from protein breakdown
•uric acid from purine (DNA) breakdown
•creatinine from muscle metabolism
other solutes •potassium, phosphate, sulfate,
calcium, magnesium, bicarb, etc.
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Abnormal Urine
abnormality cause
glycosuria •high serum glucose (>250-300), exceeds rate of reabsorption
by PCT
•diabetes
albuminuria •disruption of glomerular filtration membrane allows plasma
protein albumin to pass through
•physiologic: exertion, pregnancy, high protein intake
•pathologic: HTN, diabetes, trauma, bacterial toxins, etc
ketonuria •ketones in urine are a sign of excessive fat metabolism
•gives urine a fruity, alcohol smell
•diabetes, weight loss, starvation
hematuria •red blood cells in urine
•urine can be normally red from beets, red dyes, some drugs
•nephrolithiasis (kidney stones), infections, trauma, disruption
of filtration membrane
Abnormal Urine
abnormality cause
bilirubinuria •due to accumulation of biliruben in the blood due to liver
disease
•cirrhosis of liver, hepatitis, gall stone obstruction of CBD
urobilinogen •none could mean renal disease or biliary obstruction
•increased could mean hepatitis, cirrhosis, biliary disease
pyuria •white blood cells in the urine
•causes urine to look cloudy and consistency is thicker
•bladder infection (cystitis), kidney infection (pyelonephritis)
hemoglobinuria •presence of hemoglobin (sign of hemolysis)
•hemolytic anemia, transfusion reactions, burns
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Urine Micro
cause
epithelial cells •normal, due to shedding of cells along the urinary tract
casts •caused by accumulation of materials in the tubules which
eventually gets flushed out
•WBC casts, RBC casts
white blood cells •indicates either a bladder or kidney infection
red blood cells •indicates either an infection or stones
crystals •accumulation of solutes combined with deydration can cause
crystals to precipitate and eventually form stones
• uric acid and calcium stones are the most common
Dipstick Colors
Leukocytes
normal is white (neg)
any purple color is positive
pyuria: leukocytes in urine
cystitis: bladder infection
pyelonephritis: kidney infection
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Dipstick Colors
Nitrite
normal is white (neg)
any pink color is positive
measures chemical produced by gram negative rods like E. Coli
Dipstick Colors
pH
large range from 4.5 to 8.0
depends on what diet is like
low pH: high protein diet, ketoacidosis
uric acid can precipitate in acidic urine
high pH: vegetarian diet
phosphates precipitate in alkaline urine
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Dipstick Colors
Protein
normal is negative
proteins cannot pass through glomerulus
can be a normal condition after
strenuous exercise, during pregnancy, excessive protein consumption
Dipstick Colors
Glucose
normal is negative
filtered load of glucose exceeding the maximal tubular reabsorptive capacity
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Dipstick Colors
Ketones
normal is negative
may be present during fasting, diabetes, etc.
Dipstick Colors
Urobilinogen
a small amount is normal
may be present during fasting, diabetes, etc.
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Dipstick Colors
Bilirubin
normal is negative
if bilirubin is high yellow foam can form when shaking a sample
Dipstick Colors
Blood
normal is negative
kidney stone, UTI, bladder tumor, menstruation
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More on solutes
Sulfates
normal in urine
determined by intake of sulfur containing amino acids (protein)
Phosphates
normal in urine
important for buffering H+ in the collecting duct
Chlorides
major extracellular anion
used to maintain electrical neutrality
More on solutes
Urea
end product from ammonia from amino acid breakdown
Uric acid
end product from purine
breakdown
Creatinine
part of muscle breakdown from creatine phosphate
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Microscopic Examination
WBC’s
Normal
men < 2 WBC/HPF
women < 5 WBC/HPF
WBC’s in urine can be a sign of
inflammation along the urinary tract
Microscopic Examination
Hematuria
Not normally found in urine
can appear normal or crenated depending on hypertonicity of urine
dysmorphic RBC’s can be a sign of glomerular disease
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Microscopic Examination
Epithelial Cells
too many squamous cells might be a sign of poor specimen collection
transitional cells from renal pelvis, ureters, bladder or urethra
large sheets of transitional cells
may be a sign of cancer
Microscopic Examination
Bacteria
small amount may be from contamination
large amount may be sign of infection
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Microscopic Examination
Crystals
Struvite
can form in alkaline urine, UTI with ureas producing bacteria (raise pH by
increasing free amonia)
Uric Acid
gout (high serum uric acid concentration)
Calcium Oxalate
can occur in any urine pH
asparagus, ethylene glycol
Microscopic Examination
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Microscopic Examination
Casts
fragments of material that gets caught in the DCT and collecting ducts
usually a sign of pathology
hyaline casts made of mucoprotein secreted by
tubule cells
low urine flow, high salt concentration, low pH
RBC casts
sign of glomerulonephritis
WBC casts
indicates pyelonephritis or interstitial nephritis
Microscopic Examination
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Fluid Compartments
Fluid and Electrolytes
Intracellular
All fluid inside of body cells
about 40% of body weight
high in K+, Phosphaes (HPO4--), protein
Extracellular
All fluid outside of body cells
Plasma, CSF, interstitial fluid and lymphatics make up the ECF
about 20% of body weight
high in Na+, Cl-, bicarb
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Comparison Between Fluid Components
Acids, Bases and Buffers
Buffers resist changes in pH by removing excess H+ or OH- from solution
turn strong acids and bases into weak acids and bases
Types of buffers
carbonic acid
active in ECF
protein
active in ICF and ECF
phosphate
active in ICF
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Acids, Bases and Buffers
Acidosis
pH below 7.35
causes CNS depression to coma if severe
Alkalosis
pH above 7.45
cases CNS excitability to spasms, convulsion
Body can correct these abnormalities through
respiratory compensation
increase or decrease breathing
renal compensation
change the way the kidneys handle acids or bases
Respiratory Acidosis
Cause is elevation of pCO2 of blood
Due to lack of removal of CO2 from blood
emphysema, pulmonary edema, injury to the brainstem & respiratory centers
Treatment (acute phase)
ventilation therapy to increase exhalation of CO2
IV administration of bicarbonate (HCO3-)
Renal compensation (chronic phase)
increase H+ secretion
increase HCO3- reabsorption
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Respiratory Alkalosis
Arterial blood pCO2 is too low
Hyperventilation caused by high altitude, pulmonary disease, stroke, anxiety, aspirin overdose
Treatment (acute phase)
breathe into a paper bagor better yet, fix the lung problem
Renal compensation (chronic phase)decrease H+ secretion
decrease HCO3- reabsorption
Metabolic Acidosis
Blood bicarbonate ion concentration too low
loss of bicarb through diarrhea or kidney dysfunction
production of fixed oragnic acids (lactic acid, ketones)
kidney failing to remove H+ from protein metabolism
Treatment
IV administration of sodium bicarbonate
correct the cause
Respiratory compensation
hyperventilation
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Metabolic Alkalosis
Blood bicarbonate levels are too high
Cause is nonrespiratory loss of acid
vomiting, gastric suctioning, dehydration, excessive intake of alkaline drugs
Treatment
fluid and electrolyte therapy
correct the cause
Respiratory compensation
hypoventilation
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