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URINE ANALYSIS
Learning Objectives
zExplain urine formation zDifferentiate type of samples and samples collection zEl bElaborate physical appearance and t h i l d composition of normal urine zExplain Full Examination, Microscopic Examination (FEME) test
Function of Renal
zPrimary 9 Regulate and selective substances, to maintain solute concentration and fluid volumesvolumes 9 Achieved by glomerular filtration, tubular reabsorption, and tubular secretion mechanisms
z Secondary
9 Hormones secretion a) Renin, prostaglandins, bradykinin b)b) EErythropoietin th i ti c) 1,25 (OH)2 cholecalciferol
Urine Formation
zUrine: composed of water, electrolytes and waste products that filtered out of blood system zzBlood filtered in nephrons produced urineBlood filtered in nephrons produced urine z3 processes: filtration, reabsorption and secretion
Filtration
zBlood filtered through glomeruli and flows into Bowman’s capsule
zGlomerular filtration vs. glomerular filtrate
zGlGl omerular filtrate: water, excess salt,l filt t t lt glucose and urea
zGFR = 125 ml per minute
Reabsorption
zSubstances out of renal tubules back into blood capillaries around tubules
zSubstances: water, glucose, nutrient, sodium and ionssodium and ions
zBegins in PCT and continues in the loop of Henle, DCT, and collecting tubules
Secretion
zSubstances move into distal and collecting tubules from blood in capillaries around tubules zSubstances mix with water and wastes and converted into urine
zSecreted by active transport or diffusion mechanism zSecretion maintain body’s acid-base balance
24hr Urine Preservation
z No preservative: assay for heavy metals or estriol z Refrigerated only: amylase, hCG, total protein, Bence- Jones protein, electrolytes, drugs z Sodium carbonate (5gm) and protect from light: prophyrinp p y z Hydrochloric acid (15ml): levulinic acid, calcium and phosphorus z Glacial acetic acid: steroids and catecholamine metabolites z Boric acid: uric acid, creatinine, protein, amino acid, cortisol
TRANSPORTATION & STORAGE
z Urine specimens should be submitted immediately or delivered within 2 hours of collection or refrigerated and transported to the lab as soon as possible. z Specimen for urinalysis should be examined while fresh z Specimen left at room temp will begin decompose resulting in chemical & microscopic changes
z Minimum of 12 ml of urine should be submitted for analysis. z Smaller sample quantities will be analyzed but the statement “QNS FOR ACCURACY: < 5 ML SUBMITTED FOR ANALYSIS” will accompany results ofSUBMITTED FOR ANALYSIS will accompany results of those specimens with volumes < 5 ml., e.g., babies or newborns. z For pregnancy testing : first morning specimens are the best for pregnancy testing because the urine is more concentrated.
INVESTIGATION OF RENAL
FUNCTION
URINALYSIS (FEME) CREATININE CLEARANCECREATININE CLEARANCE SERUM CREATININE AND UREA
URINALYSIS (FEME)
zPhysical examination / Macroscopic zChemistry Test zMicroscopic Examination
Physical examination of urine
z Volume a ) physiological factor -increase intake of water -temperature -physical activityh i l ti it -others due to diuretic drugs, coffee and alcohol -normal adult urine volume : 600-1200ml/24 hours -difference in urine volume due to: polyuria, oliguria, anuria and nocturia
Normal urine output - 1-2 L per day Less than 1L daily of urine –---- Oligouria More than 2L ----------------------------- Polyuria Having NO urine output ----------- Anuria
z Colour
- normal : pale yellowish- urochrom pigment
- abnormal : due to food intake and drugs Red : beets, rhubarb (alkaline urine) Orange-yellowish : carrot, antibiotic Green, blue-green : drugs eg: amitrypline Dark brown : drugs eg: methyldopa, metronidazole
- abnormal : due to pathological Red/maroon : rbc, hemoglobin, myoglobin ‘wine-red’ : porphyrin Dark brown : melanin, homogentisic acid Yellowish-brown or greenish-brown : bilirubin, bile pigment
Refractometer
Instrument to determine the specific gravity
FEME- Physical Observation
Colour Indication Yellow Normal Amber Conjugated bilirubin Red Hemoglobin, myoglobin, porphyria, drugs Smoky/brown Altered blood, alkaptonuria, melanin Dark orange Drugs (pyridium, rifampin) Bright blue Drugs (methylene blue) Fluorescent yellow Vitamins Foamy Proteinuria, conjugated biliurubin, pyridium Turbid/cloudy WBCs, urates, phosphates Fat globules on surface
Fat embolization
z Odour z normal: aromatic odour due to presence of volatile organic acids
- Food and drugs causes characteristic odour e.g: methyl salicylic, asparagus
- Ketosis : fruity/sweetKetosis : fruity/sweet
- Congenital metabolism disorder : e.g: phenylketonuria ‘mousy’ z bacteria starts working on urea in urine using urease enzyme, so the urea is broken down to carbon dioxide & ammonia ( CO2 + NH3 ); so the urine has ammonia odor
z Appearance/ transparency Normal: -Slight turbidity: mucus (in women), squamous epithelial cell -Turbidity: calcium oxalate, uric acid, amorphous phosphate amorphous uratesphosphate, amorphous urates
Abnormal: -turbid-red : rbc -turbid : bacterial or yeast infection -milky: lipid
Normal urine composition
z Urea
- End product of protein metabolism
- 50% from urine composition
- 25-30 g/24hr z Uric acid
- End product of purine metabolism
- 0.5-1 g/24hr z Creatinine
- Skeletal muscle tissue
z Creatine
- Can be found in muscle tissues in form of phosphocreatin z Sulphur
- Protein intake z Indican
- Triptophan katabolism in intestine z Ammonia
- Final product of protein metabolism z Chloride
- Second largest composition found in urine
- Excreted in form of NaCl : 10-15g/24hr urine z Phosphate
- Protein intake
- 1.1g/24hr urine
Pathological urine composition
z Glucose – Glucosuria { indicates diabetes mellitus , excessive glucose in diet z Protein – Albuminuria { indicates liver & kidney diseases and z Ketones - Ketonuria z Pus cellsPus cells z Red blood cells – hematuria { indicates Bilharziasis/Schistosomiasis z Lipid z Amino acid z Bile pigment - jaundice z Calculi
MICROSCOPIC URINALYSIS
Urine sample (usually 10-15 ml) is centrifuged in a test tube at low speed for 5- 10 minutes The supernate is decanted and a volume of 0.2 to 0.5 ml is left inside the tube. The sediment is resuspended in the remaining supernate by flicking the bottom of the tube several times. A drop of resuspended sediment is placed on a glass slide and coverslipped.
ELEMENTS
Red blood cells
White blood cells
BBacteria t i
Crystals
Casts
RED BLOOD CELLS
Hematuria - presence of abnormal numbers of red cells in urine Due to: glomerular damage, tumors of urinary tract, kidney trauma, urinary tract stones, renal infarcts, acute tubular necrosis, upper and lower urinary tract infections, nephrotoxins, and physical stress. Red cells may also contaminate urine from vagina in menstruating women or trauma produced by bladder catherization. Theoretically, no red cells should be found
y RBC's may appear normally shaped, swollen by dilute urine or crenated by concentrated urine. y Both swollen, partly hemolyzed RBC's and crenated RBC's are sometimes difficult to distinguish from WBC's in the urine.distinguish from WBC s in the urine. y The presence of dysmorphic RBC's in urine suggests a glomerular disease such as a glomerulonephritis y Dysmorphic RBC's have odd shapes as a consequence of being distorted via passage through the abnormal glomerular structure.
z Red blood cells in urine appear as refractile disks. With hypertonicity of the urine, the RBC's begin to have a crenated appearance
z Note the irregular outlines of many of these RBC's, compared to two relatively normal RBC's at the center left of the right panel. These abnormal RBC's are dysmorphic RBC's.
- Represent a collection of protein and cellular debris in a kidney tubule.
- different stages of degeneration of renal tubular epithelial cells.
- depends largely upon the length of time it remained in the tubules
- Cellular cast:
- one or more type of cells are trapped during their formation.
- shed shortly after it was formed lt h di h i h i i f ti
Casts
- result when disease processes such as ischemia, infarction, or nephrotoxicity cause degeneration and necrosis of tubular epithelial cells.
- Eg; pus cell casts, red cell casts, epithelial casts, and mixed cellular casts.
- Granular casts :
- fine granules appear in glomerular and tubular renal disease.
- waxy cast
- retained longer in the tubular system
- hyaline :
- occasionally found in normal urine but their number is increased in renal diseases.
CAST FORMATION
broad (Figure 3)****.
Urinary casts. (A) Hyaline cast (200 X); (B) erythrocyte cast (100 X); (C) leukocyte cast (100 X); (D) granular cast (100 X).
BACTERIA
z Bacteria are common in urine specimens z Due to the abundant normal microbial flora of the vagina or external urethral meatus z Also because of their ability to rapidlyy p y multiply in urine standing at room temperature. z However, the presence of any organism in catheterized or suprapubic specimens should be considered significant.
YEAST
zYeast cells may be contaminants or represent a true yeast infection. zThey are often difficult to distinguish from red cells and amorphous crystalsfrom red cells and amorphous crystals but are distinguished by their tendency to bud. zMost often – Candida; which may colonize bladder, urethra, or vagina.
CRYSTALS
z Crystallization or precipitation of salts upon standing at room temp or in refrigerated z Common crystals seen even in healthyy y patients include :
- calcium oxalate
- triple phosphate crystals &
- amorphous phosphates.
z Very uncommon crystals :
- cystine crystals in urine of neonates with congenital cystinuria or severe liver disease,,
- tyrosine crystals with congenital tyrosinosis or marked liver impairment or
- leucine crystals in patients with severe liver disease or with maple syrup urine disease.
Common crystals
Calcium Phosphate Crystal
Uncommon crystals
Cysteine crystal
Urinary crystals. (A) Calcium oxalate crystals (arrows; 100 X); (B) uric acid crystals (100 X); (C) triple phosphate crystals with amorphous phosphates (400 X); (D) cystine crystals (100 X).
Urine Lipid Droplets
INVESTIGATION OF RENAL
FUNCTION
URINALYSIS (FEME) GFRGFR
zCREATININE CLEARANCE zSERUM CREATININE AND UREA
GLOMERULAR FILTRATION RATE
z product of the average filtration rate of each single nephron. z estimates how much blood passes through the glomeruli, each minute. z normal level GFR is approximately { 130 ml/min per 1.73 m^2 for men { 120 ml/min per 1.73 m^2 for women z variation according to age, sex, body size, physical activity, diet, pharmacologic therapy, physiologic states (eg: pregnancy) z GFR cannot be measured directly. z measured using an ideal filtration marker.
What is clearance?
zClearance tests – test to kidney function by measuring the glomerular filtration rate.
zEffects the rate at which kidney clear/filter clearance substanceclearance substance (urea/inulin/creatinine) in blood to urine through glomerulus.
Urea clearance
zend product of purine catabolism. z40% urea is reabsorbed. zamount of urea reabsorption is high with d h ddehydration. ti znot a good clearing substance to detect GFR.
Inulin clearance
zInulin - naturally occurring polysaccharides produced by many types of plants.
zExogenous substance.
zI fInfusion at a constant rate. i t t t t
zCompletely filtered by kidney.
zProblem: exogenous substance, therefore have to monitor the infusion.
Creatinine clearance
zCreatinine is just a waste product formed by slow spontaneous degradation of creatine phosphate in the process of muscle metabolismmuscle metabolism. zEndogenous waste generated from muscle zCreatinine is produced from creatine a molecule important in energy production.
Creatinine clearance
zConstant in blood.
zReliable indicator of kidney function.
zWhen kidney is impaired, the creatinine is HIGHHIGH iin blood due to poor clearance in bl d d t l i kidney.
zTherefore need to check the creatinine level in blood.
Factors that effects the Creatinine
clearance
zThe amount of creatinine produced by the body depends on the muscle mass of each person. If a person is suffering from muscle-wasting disease measurement ofmuscle wasting disease, measurement of creatinine clearance is not a reliable indicator for GFR. zConsumption of meat influence the results. Intestine absorbs creatinine from animal tissue.
Con’t
zExcess caffein consumption activate the muscular activity.
zSome drugs inhibits the tubular secretion.
zBB acteria can split the creatinine moleculet i lit th ti i l l at room temperature. Therefore it should be refrigerated or preserved.
zSevere exercise
zClearance is reported as ml/min or L/day indicates the number of ml of plasma from which the clearance substance is completely removed in one minutecompletely removed in one minute.
GFR = Urine Concentration x Urine Flow Plasma Concentration
C = U V
P
C= Clearance ml/min
U= Urine creatinine concentration in mg/dl
P= Plasma creatinine concentration in mg/dl
V= Urine volume excreted per min
CREATININE CLEARANCE
zMeasure glomerular filtration rate (GFR) zCreatinine: NOT reabsorbed and secreted by tubules zAMOUNT FILTERED AMOUNT SECRETEDAMOUNT FILTERED=AMOUNT SECRETED zCreatinine excretion dependent on GFR zCreatinine clearance = U Cr x V mL/min PCr x T
