Clinical Lab: Urinalysis
Terms
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- Urinalysis is...
-
-essential procedure for indivudals being admitted to the hospital or pre-surgical pts
-intergral part of PE
-useful indication of a healthy or diseased state
-part of routine OB checks - Urine is...
-
-readily available
-easily collected
-provides info about metabolic functions - Urine is diagnostic for...
-
-abdominal or back pain
-dysurea
-hematurea
-frequency/urgency - Value of Urine Testing...
-
-evaluates metabolic problems and other diseases (monitors/detects dz specific metabolites excreted in the urine)
-evaluates condition of the kidney/urinary tract
-evaluates endocrine problems - How can urine evaluate endocrine problems?
-
-hormones produced in the kidney that can be detected
-hormones produced outside the kidney can effect its function
-hormones excreted by the kidney in some form
-evaluates fcn (physiology) and structure (anatomy) - Urinary Tract/Kidney functions
-
-removel of waste products via blood filtering and active secretion from the blood (nitrogenous waste, metabolic acid waste)
-retention of substanced that the body needs
-maintenance of acid/base balance
-maintenance of water and electroyte balance and BP (RAAS and ADH)
-hormone synthesis and regulation (renin, eryhhtropoetin, vitamin D are sctivated by the kidney) - Glomeruli
-
-removal of meterials that need to be excreted
-prevent loss of proteins and cells into urine - Tubules
-
-reabsorb solutes that need to be conserved
-regulate Na,K, bicarb
-excrete/preserve H+ as needed - Collecting Ducts
-
-regulate the amount of water conserved or exccreted
-urine concentrated here - Composition of normal urine:
-
-water
-organic wastes (urea, creatinine, uric acid)
-inorganic wastes (chloride, sodium, potassium, ammonia, H+)
-miscellaneous - hormones, vitamins, smaller peptides, AA, trace urobilinogen, some crystals, vaginal contaminiation) - Composition of Urine in Disease:
-
-cells (RBC, WBC, renal epithelial)
-casts, protein
-mucous, bacteria
-glucose, bilirubin, increased or decreased urobilinogne, ketones, lipids
-pathological crystals - Renal Tests
-
-examination of urine
-examination of blood to measure substances affected by renal function (BUN, Creatinine)
-Dynamic measurement of blood flow, urine formation, and substance excretion - Urine Volume: Normal Adult
- 600-2500 mg/24 hours
- Urine Volume: anuria
- <100 mg/24 hours
- Urine Volume: oliguria
- <200 ml/24 hours
- Urine Volume: polyurea
- >2500 ml/24 hours
- Types of urine specimens
-
-random
-first AM void
-clean-catch
-mid-stream
-catheter collection
-supra-pubic aspitation - Routine urinalysis includes:
-
-physical exam of urine specimen
-chemical testing/screening
-microscopic exam of sediment - Standard Urinalysis includes:
-
-color/appearance
-pH
-specific gravity
-protein
-glucose
-ketones
-WBCs
-hemoglobin
-bilirubin
-urobilinogen
-nitrates
-microscopic evaluation of sediment if needed - Color of urine: normal
- amber, clear
- Color of urine is due to...
- pigement urochrome
- Color of urine is affected by...
- foods, meds, dyes, blood
- Urine color: Red
-
-blood
-should be considered pathologic until proven otherwise
-most common cause is menstrual blood
-tumor, trauma, stones, infection - Urine color: brown
-
-melanin
-blood - Urine color: dark orange
-
-bile
-pyridium - Urine Color: pink
- -urates
- Dark urine
-
-sweating
-fever
-dehydration
-jaundice - Colorless urine
-
-drug therapy (diuretics)
-overhydration
-diabetes insipidis
-glycosurea - normal clarity of urine..
- clear to slightly hazy
- Cloudy urine:
- -alkaline urine from phosphates, carbonates
- Tubidity of urine:
- -mucus, WBCs, semen
- Specific gravity
-
-relative proportaion of dissolved solid components to total volume of urine
-compares weight of urine to weight of distilled water (has specific gravity of 1.000)
-used to evaluate concentrating and excreting power of the kidney - Specific gravity can be measured by...
-
-refractometer
-reagent strip
-urinometer - Specific Gravity: Normal range
- 1.005 - 1.030
- Low specific gravity may indicate...
-
-dilute urine
-diabetes indipidis
-glomerulonephritis
-pyelonephritis - High specific gravity may indicate...
-
-concetrated urine
-adrenal insufficiency
-hepatic disease
-CHF
-high solutes (glucose, protein)
-dehydration (vomiting0 - Osmolarity
-
-number of particles of solute per unit of solution
-more exact measure of concentration - Urinalysis: pH
-
-measurement of hydrogen ion concentration
-reflects works of the kidneys to maintain normal pH homeostasis
-useful for evaluation and identification of crystals and predisposition to kidney stones - What helps the body maintain a normal acid/base balance?
- -tubular sodium reabsorption and secretion of H+ and ammonium ion
- pH normal range
- 4.5-8.0 (usually 5-6)
- Acidic pH
-
<7.0
-mediciations
-systemic acidosis
-uncontrolled diabetes
-starvation - Alkaline pH
-
->7.0
-medications (streptomycin, neomycin, kanamycin)
-UTI - Urinalysis: Blood
- -normally, no blood in urine
- Urinalysis: Hematuria
-
-intact red blood cells in the urine
-lower UTI, lupus, strenuous exercise, anticoagulants, stones, hemophilia, glomerulonephritis, trauma, menstruation, CA - Urinalysis: Hemaglobinurea
-
-free hemoglobin in the urine
-burns, crush injuries, transfusion reactions, malaria - Leukocyte Esterase
- -INDIRECT test that detects the presence of WBCs and indirectly the presence of infection (specifically UTI)
- Leukocyte esterase: normal
- negative
- Leukocyte esterase: sensitivity/specificity
-
sensitivity: 76-95%
specificity: 65-95% - Nitrite
-
-indirect test for bacteruria (usually UTI)
-most gram negative bacteria will reduce nitrate to nitrite - Nitrite: normal
- negative
- What bacteria do not convert nitrate to nitrite?
- staph and strep (gram positive)
- Does negative nitite test indicate that there is NO UTI?
-
NO, it does not necessarily mean that there is no UTI
-it takes time for the conversion from nitrate to nitrite so it make get flushed out before it converts AND many gram positives do not convert nitrate to nitrite - What specimen would be best for nitrite?
- -first morning void (long bladder incubation)
- Ketones
-
-formed from metabolism of FFA and fat
-consist of 3 substances: beta-hydroxybuteric acid, acetoacetic acid, acetone - ketoacidosis occurs when...
- carbohydrate metabolism is altered and fat becomes the predominant fuel
- Causes of ketourea...
-
-diabetes (most common)
-high fat/low carb, or high protein diets
-starvation
-prolonged vomiting
-glycogen storage diseasee
-increased metabolic states (hyperthyroidism, pregnancy, lactation, acute illness, stress, fever) - Who is particularly prone to developing ketourea?
- children
- Ketones: sensitivity
- 5-10 mg/dl
- Ketones: false negatives d/t
-
-drugs
-high Sg low pH urine - Most chemical tests for ketones employ which reagant?
-
nitroprusside reagant
reacts with acetoacetic acid in urine but not with the other consituents (beta hydroxybuteric acid, acteone) - Bilirubin
- formed from breakdown of hemoglobin
- unconjugated bilirubin
-
-indirect bilirubin
-linked to albumin
-water insuluble
-NOT found in urine - conjugated bilirubin
-
-direct bilirubin
-water solubale
-may be found in urine
-conjugated in liver and excreted in bile - Increased bilirubin levels are secondary to ....
- biliary tract obstruction
- 2 types of biliary obstruction:
-
1. extrahepatic
2. intrahepatic - Extraheptatic obstruction
- -common duct obstruction
- Intrahepatic obstruction
- -liver cell injury such as cirrhosis or viral hepatitis
- What color does Bilirubin color the urine?
- dark orange
- Bilirubin: normal
- negative
- bilirubin presence may indicate...
-
liver disease
galls stones
drug toxicity - Is there increased unconjugated bilirubin in the urine for hemolytic disease?
- NO, increased levels are NOT found
- Urobilinogen
- formed by the breakdown of bilirubin in the intestine (some reabsorbed by the portal system and removed by the liver)
- Urobilinogen: normal
-
0.1-1.0 Ehrlich units/ml
1-4 mg/24 hours - causes of increased urobilinogen..
-
-hemolytic anemia
-pernicious anemia
-hemolysis d/t drugs
-hematoma
-excessive ecchymosis - Causes of decreased urobilinogen...
-
-biliary obstruction
-cholestasis (gall stones) - Urobiulinogen: sensitivity
- one of the most sensitive tests to show impaired liver function and one of the earliest signs of acute liver cell damage
- Protein: normal
-
negative or trace
1-14 mg/24 hours - Urine protein consists of...
-
1/3 albumin
2/3 globulins - Increased proteins suggests..
-
renal disease
if more than trace protein found in urine, it must be reconfirmed by a second sample or 24 hour collection - Severe loss of protein in urine results in...
- hypoproteinemia
- Hypoproteinemia results in...
- edema
- hypoproteinemia + edema =
-
nephretic syndrome
(losses of greater than 3000 mg/24 hours) - Qualitative protein collection
-
-random sample collected tested by reagent strip or by chemical analysis
negative
trace (20 mg/dl)
1+ (50 mg/dl)
2+ (200 mg/dl)
3+ (500 mg/dl)
4+ (1 gm/dl) - Quantitative protein collection
- 24 hours collection
- Protein in urine can be 1 of 3 types:
-
1. pre-renal
2. renal proteinuria
3. post-renal proteainuria - Pre-renal proteinuria
-
-not associated with primary renal disease
-fever or toxic conditions
-venous congestion (HF, abd pressure/compression of renal veins)
-renal hypoxia (severe dehydration, shock, severe acidosis, severe anemia)
-HTN
-myxedema
-bence jones proteins - Renal proteinuria
-
-renal disease
-glomerulonephritis
-nephrotic syndrome
-destructive parenchymal lesions (tumor, infection, infarct) - Post renal proteinuria
-
-proetin added after the kidney
-cystitis
-urethriris
-prostatitis
-contamination with vaginal secretions
-infection of renal pelvis or ureter - Functional protein
-
-not associated with easily demonstrated systemic or renal damage
-sever muscular exertion
-pregnancy
-fever - Bence Jones protein
-
-immunogloblin light chains (small in easily fit through the membrane spaces)
-formed by plasma cells - Presence of BJ proteins indicates
-
-multiple myeloma (found 75% of MM pts)
-bone tumor metastasis
-Chronic lymphocytic leukemia
-macroglobulinemia
-amyloidosis - What can be used to detect Bence jones proteins?
-
-sulfasalicylic acid
-diptick will NOT detect it - Protein Test methods
-
1. heat with acetic acid
2. sulfasalicylic acid
3. dipstick
4. 24 hour - Sulfasalicylic acid test
-
-to test protein
-detects as little as 10 mg/dl
-will detect bence jones protein (globulins)
-used series of standards and compares amount of precipitation to the known standard solution - Dipstick test
-
-test for protein
-detects 20-30 mg/dl
-will react with hemoglobin but little else interferes
-false negatives if strip is left in the urine too long - 24 hour urine measurements: Advantages
-
-degree of concentration may influence results in a random UA but not with a 24
-individuals may vary with interpretation of random UA
-results are far more accurate if properly done -
24 hour urine measurements:
Disadvantages -
-incomplete sample collection
-inconvenient
-methodologies vary between labs with poor reproducibility - Increases in Microalbumin suggest...
-
-ongoing renal damage (usually associated with DM)
-HTN - Diabetic microalbumin =
-
20-200 ug/min
OR
30-300 mg/24 hours
found in 2 out of 3 samples collected within 6 months of each other - Types of glucose tests
-
1. reduction test (clinitest)
2. enzyme test (glucose oxidase) - Reduction test (clinitest)
-
-based on copper sulfate reduction by reducing substances (sugars)
-not glucose specific
-may be affected by creatinine, uric acid, fructose
-color change in test indicates presence of reducing substances - Enzyme test (glucose oxidase)
- -specific for glucose
- Microscopic exam
-
-urine is centrifuged and a drop of teh sediment is examined under low power and high-dry objectives for:
-cellular elements (RBC, WBC, Epithelial cells)
-casts
-crystals
-bacterial/protozoa - Casts
- -cylindrical masses of protein and or cells fromed in the renal tubules
- Crystals
- -often associated with stones
- Microscopic RBCs: normal
- 0-3 per hpf
- Hematurea of renal origin is often assoicated with...
- casts or proteinurea
- Increased microscopic RBCs may indicate...
-
-renal disease (stones, pyelonnephritis, cycstitis, prostatitis, malignancies)
-systemic disease (SLE, TB, Hemophilia, malignant HTN)
-bleeding into the urinary tract (trauma, tumor, thrombocytopenia, ASA overdose) - RBC casts: normals
- 0 per LPF (100x)
- RBC casts may have...
-
-intact RBCs
-degenerated RBCs
-homeglobin only - Presence of RBC casts incicates:
-
-bleeding into to nephron and is ALWAYS PATHOLOGIC
-acute inflammatory or vascular disorders in the gllomerulus
-acute glomeruloneprhitis
-renal infarction
-collagen disease
-kidney involvement in subacute bacterial endocarditis - RBC and RBC casts casutions:
-
-R/O presence of mentrual blood, vaginal bleeding, or perineal trauma
-some drugs can increase the number of RBC in urine
-Heavy smokers may have persistant RBCs in urine - Microscopic WBCs: normal
- 0-4 hpf
- WBCs may originate from...
- anywhere is the GU tract
- What test should be done in the presence of eleavted WBCs in the urine?
- urine culture
- What may contaminate the urine WBC specimen?
- vaginal discharge
- Increased WBC in urine may incdicate:
-
>50/hpf indicated bacterial infection
-all renal disease
-fever
-strenuous exerise
-bladder tumors
-chonic pyelonephritis - WBC casts: normal
-
o per lpf
may be difficular to identify - WBC casts always come from ...
- kidney
- Increased WBC casts indicates...
-
-parencyhmal infection
-pyelonephritis (most common cause)
-acute glomerulonephritis
-intersitital inflammatio of the kidneys - 3 types of Epithelial cells
-
1. renal tubular
2. bladder epithelial cells
3. squamous epithelial cells - Renal tubular Cells
-
-epithelial cell
-round and slightly larger than WBC
-single nucleus
-normal 0-2 per HPF
-come from the kidney itself
-associated with renal disease - Bladder epithelial cells
-
-epithelial cells
-larger than renal tubular cells
-shape varies from flar to columnar - Squamous epithelaial cells
-
-epiethelial cell
-large flat irregular borders
-single nucelus
-come from bladder, urethra, vagina
-common to have some in normal urine samples - How are Renal tubular cell casts formed?
- -formed from cast of epithelial cells that degenerate
- increase in renal tubular cell casts indicates...
-
-tubular damage
-nephrosis
-tubule necrosis
-glomerulonephritis
-heavy metal poisoning
-salicylate intoxication - Urine Hylaine casts:normal
-
0-2 per LPF
clear colorless casts - How are urine hylaine casts formed?
-
-formed when Tamm-Horsfall protein in tubules precipitates and gels
-clear colorless casts - Presence or urine hylaine casts depends on...
- pH, flow rates, amount of protein
- Does the presnce of Urine hylaine casts represent kidney damage?
- It may or may not
- Increased urine hyaline casts indicates...
-
-nephritis
-malignant HTN
-chronic renal disease
-diabetic nephropathy - Temporary increase in urine hylaine casts represents...
-
-stress
-strenuous exercise
-fever - Granular casts:normal
- 0-2 per LPF
- Describe granular casts
-
-homogenous
-granular
-colorless
-dense - Increased granular casts may indicate...
- -degeneration of epithelial cells
- Waxy casts: normal
- negative
- How are waxy casts formed?
- -from degenerating hylaine or granular casts collecting in the collecting tubules
- Describe waxy casts
- big broad casts formed in kidney
- Presence of waxy casts indicates...
- SERIOUS RENAL DISEASE!!
- Fatty casts:normal
- negative
- How are fatty casts formed?
- -in nephrotic syndome, fat accumulated in tubular cells and slughs off to form oval fat bodies or fatty casts
- Describe fatty casts
-
-oval fat bodies
-fat droplets - Fatty casts are the hallmark sign of ...
- -nephrotic syndrome
- Urine crystals are identified by...
-
-shape
-size
-solubility characteristics
-pH of urine - Urine cystals may indiacte...
- presence of stone
- are most crystals pathologic?
-
No
also often present with no symtoms - Assessing renal functions
-
-assess the dynamics of secretion, excretion, and osmolar regulation
-measure glomerular filtration rate - Glomerular Filtration rate
-
-amount of fluid flwoing thorugh all glomeruli in a given period of time
-depends on blood flow, effective pressure across the glomerular capillary bed and tubular pressure - How is GFR measure?
- Creatinin Clearance test
- Creatinine clearance test
-
-measures GFR
-creatinine is usaally 100% excreted in the first pass through the kidney
-creatinine is a byproduct of muscle breakdown and is prodcued at a predictable rate
-amount excreted is proportainal to muslce mass
-disorders of the kidney prevent maximum excretion - Creatinine Clearance Test: normal
-
Men 85-125 ml/min
Females 75-112 ml/min
normals are age and sex dependent - Decreased creatinine clearance indicates...
-
-impaired kidney function
-renal disease
-glomerulonephtirits
-shock
-hemorrhage
-CHF
-hepatic failure - Increased creatinine clearance indicates...
-
-high CO
-pregnancy
-burns
-CO poisening - Other renal test include..
-
-BUN/Creatinine
-urine osmolality
-radiologic and nuclear medicine procedures to assess blood and urine flow as well as function and structure of kidney - Urine pregnancy test
-
-simple one step process for qualitative detection of human chorionic gonadiotropic (hCG)
-CLIA approved
-had built in control to ensure it is working properly - Urine pregnancy test detection sensitivity:
-
-detects as little as 25 mlU/ml
-detection is possible in as few as 7-10 days after conception - hCG
-
-human chorionic gonadotropic hormone
-produced by developing placenta shortly after implantation - hCG levels:
-
-100 mlU/ml by first missed period
-100,000-200,000 by the 1th to 12th wk of pregnancy - False negatives may be produced by...
- -hCG levels below sensitivity of the test
- False positives may be produced by...
-
-trophoblastic diseasee and certain non-trophoblastic tumors
-testicular CA, prostate CA, breast CA, some lung CA - Other limitations of urine pregnancy test..
- -very dilute samples may not contain representitive levels of hCG
- Which void is best for pregnancy test?
- -first morning void