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
• What is normal ua ketone level? What ketones are detected?
o Normal=negative
o Dipsticks only detect acetoacetic acid (but also contains beta-hydroxybutyric acid, acetone)
• What is predominant ketone in diabetic ketoacidosis?
o BHB; strength of reaction may not correlate with severity of acidosis
• What conditions show ketonuria?
o DM: more common in type 1
o Increased metabolic states: hyperthyroidism, fever, pregnancy
• What gives ketone UA false (+) and false (-)?
o Pos= drugs (levodopa metabolites, phenylketones, phthaleins); highly pigmented urine
o Neg= prolonged air exposure (because ketones volatize)
• What is normal UA blood? What does it detect?
o Normal=negative
o Free Hb=lysed RBCs (hemoglobinuria); Hb=intact RBCs (hematuria); Mb (muscle protein)
• What maybe source of blood in urine?
o Glomerular dz; kidney stones, pyelonephritis, trauma, cystitis, bladder CA, prostate CA, exercise hematuria, MI, contamination
• What gives blood UA false (+) and false (-)?
o Pos= microbial peroxidases; myoglobinuria; menstrual blood
o Neg= nitrites; ascorbic acid; increased SG decreases test reactivity
• What is normal UA pH? How do kidneys maintain acid-base balance? When is it higher?
o 4.5-8.0 (usually 6.0)
o Re-absorption of Na and excretion of H+
o Higher after meals (“alkaline tide”)
• What is pH run over effect?
o Buffers from protein test (ph=3) spill to pH test, making pH look more acidic
• What is ddx for alkaline pH?
o Alkalosis: metabolic or respiratory o UTI (proteus, pseudomonas) o Gastric suction, vomiting, renal tubular acidosis o Diet: vegetarians, high citrus intake
• What is ddx for acidic pH?
o Acidosis: respiratory or metabolic o DM o Starvation o COPD o UTI (E coli) o Diet: high meat, cranberries
• What is normal protein? What does it indicate? What is function of slit pores?
o Negative: undetectable < 150 mg/day
o Sensitive indicator of Kidney function
o In normal glomerular membrane are too small for high MW proteins; have neg charge to repel proteins
• What are causes of proteinuria?
o Functional renal: severe muscular exertion; pregnancy; glomerulonephritis; nephrotic syndrome; orthostatic proteinuria; renal tumor/infection
o Pre-renal: fever; renal hypoxia; hypertension
o Post-renal: cystitis; urethritis/prostatitis; contamination w/ vaginal secretions
• When does transient proteinuria occur? What does 1+ mean?
o Fever, stress, exercise, CHF
o 30 mg/dL=significant
• What is the protein confirmation qualitative test?
o Sulfosalicylic acid (SSA + heat) precipitation test, more than just albumin o 0, 0-no turbidity o 1-10, Trace-slight turbidity o 10-30, 1+ print can be read o 40-100, 2+ white cloud w/o precipitate o 150-350, 3+ white cloud w/ fine precip o >500, 4+ flocculent precipitate
• What gives protein UA false (+) and (-)? What does it detect?
o Pos=vaginal secretions, hematuria, pyridium, highly alkaline
o Neg=dilute
o Most sensitive to albumin
o Doesn’t detect: globulins, glycoproteins, bence-jones proteins
• What is normal bilirubin UA?
o Negative
• How does bilirubin get in urine?
o Lysed RBCs -> Hb -> heme and globin -> biliverdin -> reduced to unconjugated bilirubin (not soluble) -> liver via albumin -> conj w/ Glucuronic acid -> conjugated bilirubin (soluble) -> secreted by hepatocytes into bile -> excretion in feces
• What can cause bilirubinuria?
o Gallstones
o Cholestasis: drugs, pregnancy
o Bile duct obstruction; intrahepatic or Extrahepatic
o Acute hepatitis
o Congenital defects in bilirubin metabolism (Dubin-Johnson syndrome, Rotor’s syndrome)
• What causes false (+) and (-) in bilirubin UA?
o Pos=fecal contamination; Rx: pyridium indicans
o Neg= nitrites, light, ascorbic acid
• How does urobilinogen get in urine?
o From metabolism of conjugated bilirubin by intestinal flora
o Most is further metabolized to stercobilin and excreted with stool
o Some reabsorbed via Enterohepatic circulation -> liver; most re-secreted into bile,
o **some into general circulation -> excreted by kidneys
• What is normal UA urobilinogen? Increased by? Decreased?
o Normal= 0.2-1.0 mg/dL
o High= intravascular hemolysis, intestinal obstruction, early stages of acute hepatitis
o Low= occurs, but dipstick doesn’t have sensitivity to detect it
• What causes false (+) and (-) for UA urobilinogen?
o Pos= fecal contamination, beets, pigmented drug metabolites
o Neg= antibiotics, formaldehyde, prolonged air exposure
• What are normal UA nitrite levels? Increased by?
o Normal= negative
o High= indicates UTI; many gram (-) bacteria produce enzyme nitrate reductase -> reduce urinary nitrAtes to nitrItes
• What causes false (+) and (-) UA nitrites?
o Pos= pyridium; beets; bacterial growth in old samples
o Neg= ascorbic acid; low nitrate diet; high SG
• What is normal UA leukocyte esterase? What does it indicate?
o Normal = negative
o Screen for WBCs = likelihood of UTI
o Pts may be asymptomatic even with a significant infection
o Non-urinary causes: appendicitis, pancreatitis
• What causes false (+) and (-) UA leukocyte esterase?
o Pos= vaginal secretions
o Neg= glucose, protein, increased SG, oxalates, some abx
• What is microscopic urine analysis?
o Centrifuged and sediment is examined for formed elements
o Epithelial cells, RBCs, WBCs, mucus, bacteria, casts, crystals, yeast
o Artifacts (starch/talc crystals, fibers)
o Trichomonas vaginalis
o Eggs of schitosoma haemotobium
o Pinworm eggs
• What are abnormal findings per High power field (HPF, 400x)?
o >3 erythrocytes
o > 5 leukocytes
o > 2 renal tubular cells
o > 10 bacteria
• What are abnormal findings per low power field (LPF, 200x)?
o > 3 hyaline casts or > 1 granular cast
o > 10 squamous cells (indicate contamination)
o Any other cast (RBCs, WBCs)
• Presence of what other things is abnormal?
o Fungal hyphae or yeast, parasite, viral inclusions
o Pathological crystals (cysteine, leucine, tyrosine)
o Large number of uric acid or calcium oxalate crystals
• What/why are common findings of bacteria in urine?
o Normal urine is sterile
o Most are gram (-) due to nearby GI tract
o May be contaminants from skin or genital tract
o Need to correlate with sxs and dip findings to evaluate significance
• What is appearance of microscopic yeast?
o Budding and branching
o Smooth, colorless, oval, doubly refractile walls, candida albicans is most common
o If pt has glucose in urine; often immunocompromised
• Where are epithelial cells from in urine?
o Squamous (SEC)- contaminant from lower GU (distal 1/3 of urethra) o Transitional (TEC)- line urinary tract from renal pelvis to proximal 2/3 of urethra; occasional seen o Renal (REC)- from renal tubules, sometimes slough off, so rare cells are OK; more if tubular damage, pyelonephritis, other renal dz/trauma
• What is microscopic appearance of SEC? TEC? REC?
o SEC: Large, flat, irregular-shaped cells
o TEC: 2-4x larger than leukocytes, round, pear-shaped, tail-like projections, large round nucleus
o REC: slightly larger than WBC, flat, cuboidal or columnar, one large round nucleus
• Microscopic appearance of RBC? Normal?
o Pale or yellowish, smooth biconcave disc, no nucleus or cytoplasmic granules
o Normal= < 3 RBC/HPF
• Where are casts from? Appearance?
o Formed in distal and collecting tubules (=same shape as tubule, =renal dz only)
o Colorless, semi-transparent “cigar” shape, usu w/o defined edges
o Cylindroids have tapered tail, formed in loop of Henle
o Acellular or cellular
• Why do casts form? Associated with?
o Ph acidic, urine concentrated; readily dissolve in alkaline urine
o Assoc with proteinuria and urinary stasis
• What are hyaline casts?
o Conglomerations of protein, indication of proteinuria
o Occasionally in normal urine
o Tamm-horsfall protein, a globulin, NOT detected on dipstick
o Short-term proteinuria: after exercise, fever, orthostatic proteinuria
o Appearance: large, transparent
• What are chronic hyaline casts/proteinuria assoc with?
o Glomerulonephritis, pyelonephritis, CHF, CRF (chronic renal failure)
• What are RBC casts?
o Formed in distal convoluted tubule; appear very dark, can see cell outline
o Pathological- bleeding from kidney due to reduced urine flow (RBCs + RBC casts means blood from kidney, not other part of urinary tract)
o Glomerulonephritis (PSGN); SBE (subacute bacterial endocarditis); renal infarcts, vasculitis, sickle cell anemia; SLE, malignant HTN, goodpasture’s syndrome
• What are WBC casts?
o Mean infectious or inflammatory dz of kidney; Presence excludes lower urinary tract as source
o Acute pyelonephritis; glomerulonephritis; lupus nephritis
o Bigger and paler than RBC casts, can see cytoplasm contents
• What are renal tubular epithelial (RTE) cell casts?
o Found in dzs that damage tubule epithelium: nephrosis, amyloidosis, heavy metal or other poisoning, glomerulonephritis, acute tubular necrosis, pyelonephritis
o Looks similar to WBC cast
o You can always get casts a mix of diff cell types, more often than not
• What are other types of casts?
o Granular- degenerated cellular casts (stuck in tubule long time, eventually breaks down, looks granular, can’t see cells)
o Waxy or “broad”- degenerated granular casts, chronic destructive renal dz; “renal failure cast”; casts get wider as get older
o Fatty- chronic renal dz, nephrosis, nephrotic syndrome
• What are crystals in urine?
o Not necessarily pathologic (dietary influences)
o Types depend on pH
o Can help dx metabolic dzs
o UTIs caused by proteus assoc with triple phosphate crystals (geometric)
