Week 2 UA Flashcards
Where does concentration of dilution of urine occur? Secretion? What is it all influenced by?
o Loop of Henle, distal tubules, collecting ducts
o Proximal convoluted tubules
o BP, ADH, acid-base balance, fluid balance, nutrient intake
• What is urine? Components? How much produced every day?
o Continuously formed ultra-filtrate of plasma
o Urea, chloride, sodium, potassium, creatinine, bicarb, uric acid
o 1 -1.8 (avg ~ 1.4) L every day from 17 L of filtered plasma
Urine is old dx technique. What does it reveal?
Kidney, liver fxn; metabolic processes; infx dz; nutritional status; occult dz
What occult dzs can urinalysis reveal?
Glomerulonephritis; hypertensive nephropathy; renal failure; DM (end stage renal dz); urinary tract neoplasms
What acute conditions is urinalysis a good tool for?
Abdominal pain; back pain; dysuria; urinary frequency/urgency; hematuria
What dzs is urinalysis routine monitoring for? Routine screening?
Chronic renal dz; liver dz; high BP; diabetes
Annual check-up; family hx renal dz
What are the major causes of end stage renal dz?
Diabetes; high BP; glomerulonephritis; cystic kidney dz; other
How should a urine sample best be collected?
Fresh voided; analyze in 1 hr at rm temp (cells and casts will degen over time; bacterial overgrowth will alter results); ok to fridge up to 4 hrs
What is the “clean catch mid-stream” method?
o Cleanse external genitalia w/ mild antiseptic, begin urinating, then position container to collect sample
o Decrease potential contamination of: skin, vaginal cells, bacteria
• What are other UA specimen collection methods?
o Voided urine
o Bagged specimen (pediatric)
o Hospitalization: suprapubic aspiration; catheterization
• Why is first morning void the best sample? Disadvantage? Is it practical?
o Most concentrated sample of day; best for protein, bilirubin, nitrites, ability to concentrate urine
o Not great for cells or casts which can deteriorate in bladder overnight
o Not practical; random specimens typically collected in office
• What are physical measurements/components of urinalysis?
o Physical (macroscopic): color, clarity, sp gravity
o Chemical composition (dip stick): pH, protein, bilirubin, ketones, leukocyte esterase, glucose, blood, urobilinogen, nitrite
o Microscopic: cells, microorganisms, casts, crystals, debris
• What is normal color of urine?
o Yellow: pale to deep, or amber
o Pigment is urochrome (urobilin), from bilirubin metabolism
o Usually darker, higher sp grav in concentrated urine
o Pale dilute urine is straw, or colorless
• What are 2 non-pathological colors of urine?
o Red: beets, rhubarb, menstrual blood
o Bright Yellow: riboflavin (B2)
• What are pathological colors of urine?
o Red/brown: hematuria: intact RBCs; hemoglobinuria: lysed cells
o Orange/amber: bilirubinuria: jaundice
o Green: infection: pseudomonas
o Brown/black: melanin: malignant melanoma
o Colorless: very dilute: DM, DI
o Many drugs affect color
• What are different aspects of the clarity of urine?
o Normal: clear o Cloudy: WBCs, bacteria, amorphous urates (acidic), amorphous phosphates (alkaline), epithelial cells, hyperuricosuria (purine rich foods) o Hazy: mucus, protein o Milky: fat/lipids o Smoky: RBCs
• What are some causes of different odors to urine?
o Sweet/fruity: uncontrolled diabetes (ketonuria)
o Foul/pungent: bacterial infection (ammonia)
o Musty: phenylketonuria (PKU)
o Fruity/grape juice: pseudomonas infection
o Maple syrup: maple syrup urine dz
• What tests are on a UA dipstick? What can give false (-)?
o 10: glucose, bilirubin, ketones, sp gravity, blood, pH, protein, urobilinogen, nitrite, leukocyte esterase
o Some have ascorbic acid: false (-) by reacting with reagents on test strip
• What does sp gravity indicative of? How can it be measured?
o Concentration abilities of kidneys; hydration status
o Refractometer: manual method of determining SG; replaced
• Normal values of sp grav? Distilled water?
o Water= 1.000
o Normal= 1.005-1.030
o Usually= 1.010-1.025
o Under 2 yrs= 1.001-1.018
• What is high/low SG called?
o High=hypersthenuria, >1.025
o Low-hyposthenuria, 1.001-1.010
• What are the 2 measures of solute concentration in urine?
o Specific gravity
o Osmolality: preferred for pts with renal dz
• What are some pathologies which show increased SG? Decreased?
o Diabetes mellitus- glycosuria; proteinuria/nephrotic syndrome; drug effects, eg radiographic contrast dyes; dehydration; SIADH (pituitary tumor); CHF; toxemia of pregnancy
o High fluid intake; chronic renal dzs (always at 1.010=isosthenuria); diabetes insipidus (ADH insufficiency); diuretics; glomerulonephritis
• What will give a high false positive SG? Low false positive?
o High= proteinuria -> over-estimation of kidney concentration ability
o Low= highly buffered alkaline urine; >1% glucose or urea
• How is glucose filtered by kidneys? How much should be in urine?
o By glomerulus; filtrate levels approximate blood glucose levels; reabsorbed in proximal renal tubules
o None, unless blood levels over 160-180 mg/dL -> glucosuria
o Normal is <0.5 g per day
o Few ppl normally have a little glucose due to less efficient renal tubules
• What are causes of glucosuria?
o DM, Cushing’s syndrome, pheochromocytoma, acromegaly (chronic pancreatitis, drugs…)
• What do you do if you find unexpected glucosuria?
o Test blood for glucose
What gives glucose false (+)? False (-)?
o Pos= oxidizing agents
o Neg= ketones, ascorbic acid, aspirin
o Also, reactivity of glucose test decreases as SG increases
What causes ketones in urine? What does it mean?
o From metabolism of fatty acids and fats
o Result of altered carb metabolism
o Higher conc in blood leads to: electrolyte imbalance, dehydration, acidosis and eventual coma