URINALYSIS
(NPLEX )
I. Indications for Performing Urinalysis
A. Suspicion of GU tract disease
-urethritis, cystitis, ureteritis, pyelonephritis, glomerulonephritis, prostatitis, urinary stones
B. Screening test for diabetes and diabetic ketoacidosis, hyperbilirubinemia, multiple myeloma,
diabetes insipidis, hepatic or biliary tract disease
C. Part of a regular screening physical with lab work-up- to uncover hidden disease
II. Interpretations of Lab Dx Results
A. Observation of the sample
1. Color
- produced by the pigments uroerythrin, urochrome, and porphyrin
- yellow, straw to amber is normal; straw means SG < 1.010, amber means SG > 1.020
a. red (straw to port wine) - blood, hemoglobin, myoglobin, uroerythrin (in acute febrile
disease), porphyria (port wine color), phenophthaleins, Dorbane (laxative), diet (beets,
blackberries), Cascara, senna, aniline dyes
b. brown - blood (acid hematin), bilirubin and other bile pigments (yellow-brown to
yellow green). urobilinogen, melanin (melanogin conversion by exposure to light in
multiple myeloma, melanotic tumor, Addison's disease), indican, phenols, drugs (Flagyl,
Nitrofurantoin, L-dopa, methyldopa, metronidazole, sulfonamides), Lysol poisoning
(brown-black), rhubarb
c. orange - concentrated urine (inadequate fluid intake, excessive fluid loss, fever), bile,
drugs (Pyridium, Rifampin, Aco-Gantrisin, Furoxone, Dilantin), diet (carrot juice,
carotenes, riboflavin, food dyes), uric acid crystals
d. blue / green - biliverdin (oxidation of bilirubin on standing), drugs (methylene blue,
Elavil), Indican, Pseudomonas infection
e. colorless - dilute urine from excess fluid intake, Diabetes Insipidis, Diabetes Mellitis,
ESRD, chronic interstitial nephritis, severe iron deficiency, alcohol ingestion, diuretics
f. black - alkaptonuria (homogentistic acid in tyrosine metabolic disorder)
g. smoky - RBC's
2. Odor
a. ammoniacal, fetid - bacterial growth
b. sweetish, frothy, brown - bile (bile duct obstruction)
c. fruity, sweetish - ketonuria
d. foul - fecal contamination, recto-ureteral fistula
e. mousy, musty - phenylketonuria
f. like maple syrup, sweet - maple syrup urine disease
g. any strong, unusual, persistent odor - inherited metabolic diseases
3. Appearance
a. clear - normal fresh urine
b. turbid (hazy )- cooling of the sample, pH change, RBC's
c. cloudy - unable to see through sample
1) amorphous sediment or amorphous crystals , depending on urine pH
2) pus, with WBC count > 200 cells / mm3
3) blood, with RBC count > 500 cells / mm3
4) epithelial cells
5) bacteria
6) fat - milky appearance
7) chylomicrons - creamy color - obstruction of lymph vessels by parasites,
thoracic duct obstruction, trauma, or tumor
8) conjugated bilirubin - parenchymal liver disease, biliary tract obstruction
9) urobilin - parenchymal liver disease, hemolytic disease
10) oxalic or glycolic acids
B. Dipstick
1. pH - ranges from 4.5 to 8.0, normal is 6.0 to 6.5 (6.5 optimal)
a. pH > 7.0 is found in infection with urea-splitting organisms (Proteus, Psuedomonas),
respiratory or metabolic alkalosis (hyperventilation, vomiting), hyperaldosteronism, the
post-prandial alkaline tide, a diet high in vegetables and citrus fruits and dairy products,
urine standing at room temperature, pyloric obstruction, salicylate intoxication, chronic
renal failure, ingestion of Na bicarb, K citrate or acetazolamide
b. With renal tubular acidosis, the pH is no lower than 6.0, despite systemic
acidosis, due to the inability of the tubules to secrete enough H+ ions
c. pH < 6.0 is found in respiratory or metabolic acidosis (COPD, diabetic ketoacidosis),
potassium deficiency (even with metabolic alkalosis), diarrhea, dehydration, starvation, a
high protein diet, acidifying foods (e.g. cranberries), chlorothiazide diuretics
2. Specific gravity
- ranges from 1.002 to 1.030; normal first morning urine ranges from 1.015 to 1.025; 24-hour
urine ranges from 1.015 to 1.018.
a. SG < 1.010 - excess hydration, diuretics; if in several samples, kidney disease
b. SG < 1.003 - water diuresis, Diabetes Insipidis; if consistent, ESRD
c. SG > 1.020 - decreased fluid intake, water loss (fever, sweating, vomiting, diarrhea),
diabetes mellitis, CHF, adrenal insufficiency, ADH-secreting tumors, urine preservatives
d. Will be increased by: protein, X-ray dyes, and refrigeration; dipstick is affected by
moderate changes in pH or protein, but not by glucose or X-ray dyes
3. Leukocyte esterase
a. Color change with > 5 WBC's / hpf
b. (+) result indicates pathology, either infection or inflammation: PN, acute UTI, acute
prostatitis, interstitial nephritis, AGN, lupus nephritis, urolithiasis, renal tubular necrosis,
retained foreign body, dehydration, fever, stress
c. Interference factors - glucose, Vit. C, large proteins, histiocytes, drugs
(Pyridium,
nitrofurantoin, rifampin)
d. false (+) with Trichomonas, vaginal d/c, parasites, heavy mucus
4. Protein
to
a. Color change with > 10 mg/ dl; normal AM specimen can be up to 30 mg/ dl
b. Detects primarily albumin and Tamm-Horsfall protein (albumin and globulins)
c. Trace = 5 to 20 mg; 1+ = 30 mg; 2+ = 100 mg; 3+ = 300 mg; 4+ = 1000 mg
d. Bromphenol blue does not change color in the presence of immunoglobulins (BenceJones proteins); use 3% SSA to detect; SSA (+) in multiple myeloma, tumor metastasis
the bone, CLL, amyloidosis, and macroglobulinemia
e. Proteinuria
1) Prerenal - toxic conditions (fever, poisoning), trauma, venous congestion
(CHF, renal vein compression), renal hypoxia (severe dehydration, shock, severe
acidosis, acute cardiac decompensation, severe anemia), hypertension
(moderate to severe chronic, malignant, eclampsia), myxedema, hyperthyroidism,
Bence-Jones protein, convulsive disorders, liver disease, acute infections
2) Renal - Glomerular diseases (nephritis, nephrotic syndrome), destructive
parenchymal lesions (tumor, infection, infarct. polycystic kidney, TB), kidney
stones, heavy metal poisoning, Fanconi's syndrome, Wilson's disease, renal
tubular acidosis, galactosemia
3) Postrenal - infection of renal pelvis or ureter, cystitis, urethritis, prostatitis,
vaginal contamination
4) Functional - prolonged fever, severe muscular exertion, emotional stress,
exposure to cold, pregnancy and delivery, vasoconstrictive drugs, and orthostatic
proteinuria
f. Interference factors
- high pH, high salt concentration, dilute or concentrated urine, numerous WBC's or
epithelial cells (centrifuge the sample and test the supernatant; + RBC's or WBC's with protein is a lower UTI), gross hematuria, or contamination with proteins from other body
fluids or pus
g. If the value is high, the type/amount of protein lost must be determined via
electrophoretic studies and/or specific quantitative protein tests on a timed urine
collection, and the protein/creatinine ratio on a single void ( normal is < 0.2) must be
determined to accurately assess the degree of proteinuria
5. Glucose
a. Renal threshhold 160-180 mg/ dl; lower threshhold in pregnancy
b. Glycosuria
1) Hyperglycemia - DM (urine is normal if GFR is reduced), endocrine diseases
(Cushing's syndrome, pheochromocytoma, hyperthyroidism) or the administration
of hormones, liver disease, increased ICP (tumors, intracranial hemorrhage, skull
fracture), post-anaesthesia
2) Renal tubular disease - renal glucosuria, toxic renal tubular disease (carbon
monoxide, lead, mercuric chloride), inflammatory renal disease (acute GN,
nephrosis), or defective amino acid transport in renal tubules (Fanconi's
syndrome)
3) Idiopathic
c. Interference factors - false (+) with phenylketones, streptomycin, Keflin, creatinine in
conc. urine; false (-) with Vit. C, cephalosporins, aspirin, oxidizing agents, ketones
6. Ketones
a. Detects acetoacetic acid and acetone, not hydroxybutyric acid; 1 mg/ dl is normal
b. Produced in the incomplete oxidation of FA's in the absence of available CHO's
c. (+) in DM (diabetic acidosis), glycogen storage diseases; also (+) in dehydration, fever,
prolonged vomiting, starvation, fasting, alcoholism, low carbohydrate diet, N & V of
pregnancy, delivery, hyperthyroidism, (mild ketonuria in children under stress is normal)
d. (-) in kidney failure, even with high ketonemia (ketosis)
e. . Interference factors - false (+) from phthaleins, phenylketones, alcohol, insulin,
Pyridium; false (-) from aspirin or aged urine
7. Hemoglobin
a. Screens for hematuria; do microscopic analysis to confirm presence of RBC's
b. (+) with hemoglobin, myoglobin or RBC's
c. SG < 1.008 will lyse RBC's; hemoglobin will be present, but not RBC's
d. Free Hgb is excreted at a blood concentration > 140 mg/ dl, when haptoglobin, the
carrier protein, is saturated
e. (+) with UTI's, PN, AGN, urolithiasis, urinary tumors, renal infarction, malignant
hypertension, blood dyscrasias (thrombocytopenia, leukemia, hemophilia, sickle cell trait),
heavy smokers, anticoagulation drugs (coumarins, heparin, salicylates), catheterization,
RCHF, inflammation of adjoining tissues (BPH, diverticulitis), collagen diseases (lupus,
polyarteritis nodosa), SBE, trauma; (+) with myoglobinuria from muscle damage ( MI or
ischemia, electric shock, progressive muscle disease, crush injuries, severe exercise,
alcohol poisoning); (+) with hemoglobinuria ( from extensive burns and crushing injuries,
transfusion reactions, febrile intoxication, chemical agents and alkaloids, malaria,
intravascular hemolysis, and paroxysmal hemoglobinuria)
f. Interference factors - false (+) from pyuria, iodides, bromides, hypochlorite; false (-)
from Vit. C
8. Conjugated Bilirubin (Bile)
a. A result of Hgb degradation; secreted in bile, not normally found in urine
b. (+) in hepatitis and biliary obstruction (choleocholithiasis, cirrhosis of the liver,
infectious hepatitis, metastatic disease of the liver, Gilbert's disease), jaundice, CHF
c. (-) in hemolytic disease
d. Interference factors - false (+) from certain drugs; false (-) from Vit. C, exposure to
light (oxidation to urobilinogen), and nitrites
9. Urobilinogen
a. Reduced conjugated bilirubin; produced in the colon by bacteria, absorbed, and
excreted by the kidneys
b. Oxidized in the presence of light to urobilin; do test within 30 min. of voiding
c. Increased in hepatic disease with parenchymal cell damage (hepatitis, toxic damage,
cirrhosis), cholangitits, hemolysis, pernicious anemia, malaria, hemorrhage into body
tissues, infarction, chloroform and CCl4 poisoning, CHF, infectious mono, and bowel
toxicity
d. Increased in the early stage of viral hepatitis before jaundice is evident, one
of the earliest signs of acute liver cell damage
e. Absent in neonates and in complete obstruction of the common bile duct; reduced
in incomplete obstruction of the CBD, hepatitis with cholestasis, starvation, severe
diarrhea, renal insufficiency, reduction of GI bacterial flora
f. Interference factors - false (+) from bilirubin; false (-) from formaldehyde,
phenypridine, nitrites, and an aged sample; more (+) in high pH, less (+) in low pH
10. Nitrites
a. Produced by gram-negative bacteria in the urinary tract, which reduce nitrates
to nitrites (E. coli, Enterobacter, Pseudomonas )
b. (+) in UTI's, PN (may be the only sign)
c. The test is not very sensitive, a (-) result does not r/o UTI; the first morning urine
is best to allow for proper incubation
d. Interference factors - marked diuresis, restricted fluid intake, fasting, digestive
disorders, urine that has been standing; false (-) with Vit. C; false (+) with azo-dye
metabolites
C. Microscopic Evaluation
1. RBC's
a. The urine must not be too dilute or too alkaline; lysis occurs when SG < 1.008; the cells
will be crenated in hypertonic urine and pale and distended in hypotonic urine
b. Present in situations listed under Dipstick, Hemoglobin (except myoglobunuria and
hemoglobinuria)
c. Any hematuria is abnormal and should be investigated
2. WBC's
a. > 2-3 WBC's / hpf is abnormal in a specimen from a male or from catheterization or
suprapubic aspiration in a female = pyuria
b. A clean-catch specimen from a female is often contaminated with vaginal WBC's
c. See Dipstick, Leukocytes, for interpretation
d. Clumped WBC's suggests acute infection, possibly renal
e. Glitter cells (WBC's with cytoplasmic granule Brownian motion) suggests PN
f. Pyuria + significant proteinuria = renal; WBC casts confirm renal origin
Pyuria + slight or no proteinuria = lower U.T.
g. Persistent pyuria with hematuria and (-) cultures may indicate renal T.B.; do a ZiehlNielsen stain of the sediment for acid-fast bacteria
h. WBC's lyse in alkaline or hypotonic urine
3. Epithelial cells - few (0-2/ lpf), 1+ (2-10), 2+ (10-50), 3+ (50-200), 4+ (> 200)
a. Squamous
1) From contamination from the distal urethra (males) or the introitus (females)
2) Abnormal clusters or appearance may indicate malignancy of the urothelium
b. Transitional
1) From renal pelvis, calices, ureter, bladder, and proximal 2/3 of urethra
2) Common, not significant, except in large numbers
c. Renal
1) 5 types
a) Type I - proximal convoluted tubules
b) Type II - distal tubules
c) Types III and IV - collecting tubules
d) Type V - urothelium - same as transitional
2) The presence of Types I to IV indicate renal tubular damage - PN, salicylate
OD,
steroids, acute tubular necrosis, kidney transplant rejection
4. Casts
a. Produced by the gelling of Tamm-Horsfall mucoproteins or IgG or IgM during urinary
stasis in renal tubules; conform to the shape of the tubule; form only in acidic urine,
dissolve in alkaline; form in concentrated urine, dissolve in dilute urine
b. < 1/ lfp is normal; 20 - 30/ lpf in progressive renal disease
c. Red cell
1) Granular, dark red to red orange
2) Always indicate pathology; hemorrhage or desquamation of the nephron
3) Glomerulitis (AGN, Goodpasture's Syndrome, lupus nephritis, SBE, severe
injury to the GBM), Wegner's granulomatosis, pericarditis, CHF, vasculitis
(polyarteritis), sickle cell disease, acute bacterial endocarditis
d. Hemoglobin
1) Orange to yellow-red; distinguish from bilirubin or drug-stained casts
2) From the degeneration of RBC casts
3) Chronic GN, chronic kidney conditions, intravascular hemolysis (Clostridium
infection, mismatched transfusion)
e. White cell
1) Usually PMN's
2) Range from being able to see the multilobed nucleus to granular
3) Renal parenchymal infection or inflammation - APN, interstitial nephritis, lupus
nephritis, AGN
f. Epithelial cell
1) From the tubular lining; pathological
2) Form coarse granular or waxy casts
3) Often large oval or round or polyhedral nucleii are arranged in rows
4) Indicates damaged or necrotic tubular epithelium - nephrosis, nephrotic phase of
GN, nephrotic agents (ethylglycol, lead, mercuric chloride, bismuth), viruses (CMV,
hepatitis), acute kidney transplant rejection, amyloidosis
g. Granular
1) Contain disintegrated epithelial cells, WBC's, or protein; with urine stasis,
degenerate from coarse to fine
2) Indicates intrinsic renal disease; also with strenous exercise
h. Waxy
1) Transluscent, homogeneous, reflects light, undulating edges, squared ends
2) From degeneration of granular casts in severe tubule stasis
3) Chronic kidney disease, diabetic nephropathy, renal amyloidosis, severe CRF,
malignant hypertension
i. Mixed
- contain more than 1 cellular component; indicate damage to several areas of the kidney
j. Fatty
1) From degenerating tubule and glomerular cells; degenerated cells containing fat
droplets may also form free-floating oval fat bodies
2) Nephrotic syndrome - primary lipoid nephrosis, SLE, amyloidosis, subacute and
chronic GN, mercury poisoning, hypersensitivity reactions
3) With cholesterol esters - Maltese Cross appearance under polarized light;
indicate
chronic kidney disease or recovery from acute renal failure
k. Broad - severe tubule stasis and severe localized tubule damage, azotemia
l. Telescoped urinary sediments
- contain a variety of casts and cellular components; found in acute GN
m. Hyaline - mucus and globulin; non-pathological, form after exercise or in concentrated or highly acidic urine
5. Crystals
a. Formed while urine is cooling; albumin prevents their formation
b. In acid urine - pH 5.0 - 6.5
1) Uric acid - gout, acute febrile conditions, chronic nephritis
2) Amorphous urates, sodium urate - salts of Na+, K+, Mg++, Ca++; normal
3) Calcium oxalate - up to pH 7.5 ; ethylene glycol poisoning, DM, liver disease,
severe renal disease, ingestion of oxalate-rich foods
4) Cystine - pathological ; indicates an inherited metabolic condition
5) Leucine - patholocigal ; maple syrup urine disease, Oathouse urine disease,
liver
disease
6) Tyrosine - pathological ; tyrosinosis, Oathouse urine disease, liver disease
7) Hippuric acid - no significance
8) Cholesterol - indicates excessive tissue breakdown - nephrotic syndrome,
chyluria, filariasis, tumors
c. In alkaline urine - pH 7.5 - 9.0
1) Triple phosphates - ammonium-magnesium-phospate - with urinary calculi,
chronic pyelitis, chronic cystitis, BPH with urinary retention
2) Amorphous phosphates - similar to amorphous urates ; no significance
3) Calcium carbonate - no significance
4) Calcium phosphate - may form calculi
5) Ammonium urate - found with bacterial infection if in freshly voided urine
6. Other elements
a. Bacteria
1) Indicates infection; normal urine is sterile
2) Rods and cocci; cocci can be confused with amorphous phosphates/ urates
b. Yeast
1) Indicates an infection; Candida most common
2) Must be distinguished from RBC's
3) Associated with UTI's, DM
c. sperm
- may indicate sexual abuse in children and the elderly
d. Mucous - normal in smaller amounts, increased in inflammation and urolithiasis
e. Oval fat bodies - pathological - indicates degenerative disease
f. Starch crystals - powders, diapers; indicates a contaminated specimen
g. Fibers - underwear, feminine napkins; normal; indicates a contaminated specimen
Sources: Lab Dx notes from Dr. Tom Kruzel
Clinical Laboratory Medicine by Ravel
Urology by Tanagho and McAninch
Interpretation of Diagnostic Tests by Wallach
ABC's of Interpretive Laboratory Data by Bakerman
Laboratory Diagnostic Tests by Fischbach