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UrinalysisJack Mydlo, MD, MBA, FACS
Professor and Chair, Dept. of UrologyLewis Katz School of Medicine, Temple
UniversityOct 5, 2020
Disclosures Consultant for MDL Laboratories
Objectives:
1. To understand the history of urinalysis
2. To understand false negatives /positives, stone pH changes, specific grav
3. To determine the future of urinalysis
Urinalysis Laboratory medicine: 6000
year ago with analysis of human urine. Named uroscopy until 17th century
Urine analysis predated Hippocrates (by Sumerians)
Hindus noted that some urine was sweet, and attract black ants: diabetes mellitus
Galen“diarrhea of urine” DM
Early urology: venerealogists!
Stone disease: Mesopotamia 3200 BC
Hippocratic Oath
Urinalysis Preparation
Appearance
Dipstick
Microscopic
Indications
Urine specimen:Collection & Prep
Midstream urine specimen Men: retract foreskin “Clean, Pee, Catch” “CPC”
Dipstick into uncentrifuged urine
Centrifuge 10-15 ml@3000RPM for 5 mins
Decant urine, place several drops on slide
Microscopic exam Low power (100x) High power (400x)
Urine Color Normal: yellow from
pigment urochrome Red urine
Hematuria Hemoglobinuria/Myoglobinu
ria Anthrocyanin: beets and
blackberries Lead and Mercury poisoning Phenolphthalein in bowel
evacuants Phenothiazines ex:
Compazine
Urine Turbidity Cloudy urine
Pyuria/UTI
Phosphaturia: excess phosphate crystals precipitate in alkaline urine after meals after milk
Chyluria
Urine Dipstick Specific Gravity pH Leukocyte esterase Blood Nitrites Ketones Bilirubin Urobilinogen Protein Glucose
Dipstick: Leukocyte Esterase Indicates WBC’s
Produced by Neutrophils
Check 1-5 min after dip
Most indicative of UTI if both nitrites & leuk esterase are +
False negative High Spec. Grav
Glycosuria Vitamin C ingestion
Dipstick: Nitrites
Not normally found in urine
Gram negative bacteria convert nitrates to nitrites
Indicates bacteriuria Specificity > 90% Sensitivity only 35-85%
Diagnosis of UTI Need to use leukocyte esterase
in conjunction with nitrites
Can have bacteriuria without significant pyuria
Can have pyuria without bacteriuria
Most accurate: WBC and bacteria on microscopic exam, culture
Dipstick: Blood Reaction based on peroxidase
activity of hemoglobin
Positive dipstick for blood Hematuria Myoglobinuria- from
muscle Hemoglobinuria
Rule out UTI if you see + heme with nitrites/leuks
Dipstick: Blood Sensitivity >90% to detect >3
RBC/hpf but low specificity
Can only distinguish causes of + blood on dipstick by micro exam for RBC
Negative dipstick > 90% specific for absence
of RBC Do not need micro if dip is
negative
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5271483/
Evaluation of hematuria Indication for evaluation
AUA Guidelines
>3 RBC on 1 specimen
Increased risk factors Smoker chemical exposure age >40 previous gross hematuria
Neg WU: consider nephrology follow up
Dipstick: Protein Tetrabromophenol blue dye
shifts color due to pH from protein in urine- mainly albumin
Normal adult: <100 mg/day of protein 30% albumin 30% serum globulins 40% tissue proteins (Tamm-
Horsfall)
Indicators for glomerular disease, predictors for A fib
https://www.nature.com/articles/s41598-017-06579-0/
Dipstick: ProteinCauses of + dip
for protein
Glomerular disease
Tubulo-interstitial disease
Overflow of serum protein: multiple myeloma
Reno-vascular disease
Dipstick: Protein
Positive dip: need more eval:
Cutoff: 3+ protein/creatinine ratio on
spot urine (practical) 24 hour urine for protein Nephrology referral
False negatives
Protein not albumin Urine is dilute or alkaline
Dipstick: Glucose
Glucose filtered by glomeruli is absorbed by proximal tubule
Renal threshold= 180 mg/dl
Above threshold = glucosuria
Test is specific for glucose, not other sugars
Early dx of DM: refer to PCP
Dipstick: Ketones Not normally found in urine
Indicate depleted body stores of carbohydrates and breakdown of body fat
Seen in urine prior to appearance in serum
Dip + for ketones Diabetic ketoacidosis Pregnancy Starvation or rapid weight
reduction
Dipstick: BilirubinBilirubin is product of RBC breakdown:
Bound to serum albumin Water insoluble, never
found in urine
Bilirubin in urine Intrinsic hepatic disease Bile duct obstruction Should prompt evaluation
Dipstick: Urobilinogen Small amounts of
urobilinogen in urine
Formed in intestines, 50% is reabsorbed, 50% stool, urine
Passes through bile ducts to small bowel where bacteria convert bilirubin to urobilinogen
Excess urobilinogen: IncRBC breakdown, cirrhosis
Decreased urobilinogen: blockage in bile duct or bile production failure.
Dipstick: pH Colors distinguish pH 5 to 9
Average pH is 5.5 to 6.5
High urine pH Urea splitting bacteria Noted in staghorn stones
Low pH: uric acid stones Treat with K-citrate to
increase pH: dissolve stones
Dipstick: specific gravity Range 1.001 to 1.035
Reflects patient’s hydration status and/or renal concentrating ability
Cause of low SG < 1.008 Increased fluid intake Diuretics Diabetes insipidus Decreased renal
concentrating ability ADH: DCT & collecting
duct
Dipstick: Specific Gravity Causes of high SG > 1.020
Decreased fluid intake Dehydration: fever,
sweating, diarrhea, vomiting
Glucosuria: diabetes SIADH IV contrast
Urine microscopic exam
RBC WBC Cells Casts Crystals Bacteriuria
Urine microscopic exam: WBC
NormalMen 1-2 WBC/hpfWomen: up to 5 WBC/hpf
See granules in cells Indicates infection or inflammation
UTIUrinary tract stones
30
White Blood Cells
Urine micro exam: RBC Easier to distinguish types
with condenser turned down reducing background light
Circular Even distribution of
cytoplasm Tubular origin
Dysmorphic: altered shape Typical of glomerular
disease
32
Air bubbleRed blood cells
Yeast
Starch
RBC and artifacts
33 Squamous and transitional epithelial cells
squamous
transitional
Urine micro exam: Casts Casts: protein coagulum that
is formed in a renal tubule and traps luminal contents
RBC casts: glomerular bleeding from GN
WBC casts Acute GN Pyelonephritis Interstitial nephritis
Hyaline casts: contain mucoproteins, no pathologic significance
RBC Casts WBC Casts
36
Hyaline Casts
CrystalsCalcium Oxalate: Envelope
TriplePhosphate:Coffin lids
Cystine:hexagon
Uric acid: needles,toothpicks
Urine micro exam: microbes
Bacteria5 bacteria/hpf = > 100,000 cfu/ml
Yeast
Parasites
WBC’s and bacteria
Urinalysis: w catheters / stones Will be positive for WBC, RBC
Catheters: will have bacteria
UA not usually indicated in setting of catheters or stones
R/O UTI Stones- send urine culture Catheters- culture if febrile Do not treat UTI in
asymptomatic patients
The future of urinalysis UA instruments and
reagents USD: $2.14 Billion by 2022.
Market to grow 7.5%
Telemedicine and fully automated urine strip readers
Usage of smart phones for deciphering urine test strip results is expanding.
Smart phone cameras can detect presence of bacterial DNA by analyzing level of fluorescence.
The Future: microchip that will use DNA and protein to arrive at the exact diagnosis
