urine analysis lecture 9&10

8/20/2019 Urine Analysis Lecture 9&10

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Urine analysisDr. Hala Kamel

MBChB, MSc, MDAssist. prof. Biochemistry Dep.,

Faculty of Medicine

ASU & UQ


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Urine analysis

Routine urinalysis includes : physical , chemical and microscopic

examinationSpecimen

• A fresh voided morning sample is the most concentrated in termsof chemical substances and structural/cellular elements present.

• A fresh early morning specimen after overnight fasting gives themost valuable information concerning renal function andgenitourinary disease .Therefore, whenever feasible, collectspecimens routinely in early A.M.

• 24-Hour Urine Specimen is required for quantitative tests

• A mid-stream collection enhances the stability of the specimen andavoids inappropriate collections when cultures are also needed.

• A randomly voided specimen may also be tested.

• Urine specimens should be examined within 1 hour aftercollection, or else refrigerated. Elements whose main matrixconstituent is primarily of protein may start to degenerate asspecimen pH level rises.


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Physical Examination

Appearance & color

Amber yellow normal color due to urochromes

Blood (haematuria) – Check with Dipstix (blood, sugar, protein).

– Simple, cheap, routine, easy to re-check and unlikely to make mistakes.

But not quantifiable, just checks for presence.Very concentrated – dark/smoky colour.

Very clear urine with high frequency of urination indicates it’s lesslikely to be a bacterial problem.

Discoloration may also be due to: – Jaundice, haemoglobinuria.

– Drugs (e.g. antibiotics). – Food (e.g. beetroot).

– Disease (e.g. porphyria )dark brown on standing

– Brownish black in alkaptonurea


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Urine colour/appearance

Increasing concentration of urine

Urine may also be clear, bloody,

cloudy or flocculent (big bits in it).


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Volume

Temperate climates: output of 800-2500 ml/day.Dependent upon subject’s activity, hydrationstatus, diet and body size.

Polyuria: D.M . D.I., choronic renal disease Anuria/oliguria : less than 2oo ml/day:nephritis,acute renal failure, urinary obstruction

Sudden changes in volume of urine can indicate

problems with ability to concentrate urine, or infeedback mechanisms that help you control ECFvolume/osmolality


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Turbidity


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Osmolality& specific gravity

useful for determining whether ionicimbalances exist in subject.( N: 1.005-1.030)

--↑↑ in glucosuria and protienuria--↓↓ in D.I.

-- Fixed ( isothenuria) in severe renal

damage – May indicate renal failure (e.g. excess urea)

or problems with ADH.


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Urinary pH

Normally : 4.5 - 8


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Chemical Examination

Dipstix


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GlucoseCLINICAL SIGNIFICANCE

Under normal circumstances, almost all theglucose filtered by the glomerulus isreabsorbed in the proximal convolutedtubule; therefore, urine contains onlyminute amounts of glucose. Tubularreabsorption of glucose is by activetransport in response to the body’s need tomaintain an adequate concentration ofglucose. Should the blood level of glucosebecome elevated (hyperglycemia), asoccurs in diabetes mellitus, the tubulartransport of glucose ceases, and glucoseappears in the urine. The blood level atwhich tubular reabsorption stops (renalthreshold) for glucose is approximately 160

to 180 mg/dL. Blood glucose levels willfluctuate, and a normal person may haveglycosuria following a meal with a highglucose content. Therefore, the mostinformative glucose results are obtainedfrom specimens collected under controlledconditions.


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Ketones

The term ketones represents threeintermediate products of fatmetabolism, namely, acetone,acetoacetic acid, and beta-hydroxybutyric acid. Normally,measurable amounts of ketonesdo not appear in the urine,because all the metabolized fat iscompletely broken down intocarbon dioxide and water.However, when the use ofavailable carbohydrate as themajor source of energy becomescompromised and body stores of

fat must be metabolized to supplyenergy,ketones will be detected inurine.


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Blood

Blood may be present in the urineeither in the form of intact red bloodcells (hematuria ) or as the product ofred blood cell destruction,hemoglobin (hemoglobinuria ).,blood present in large quantities canbe detected visually; hematuria

produces a cloudy red urine, andhemoglobinuria appears as a clearred specimen. Because any amountof blood greater than five cells permicroliter of urine is consideredclinically significant, visualexamination cannot be relied on todetect the presence of blood.Microscopic examination of theurinary sediment will show intact redblood cells, but free hemoglobinproduced either by hemolyticdisorders or lysis of red blood cellswill not be detected.


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Bilirubin / Urobilinogin


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Bilirubin

The appearance of bilirubin in the urine can provide an earlyindication of liver disease. It is often detected long before thedevelopment of jaundice.

Conjugated bilirubin will appear in the urine when the normaldegradation cycle is disrupted by obstruction of the bile duct (e.g.,gallstones or cancer) or when the integrity of the liver is damaged,

allowing leakage of conjugated bilirubin into the circulation. Hepatitisand cirrhosis are common examples of conditions that produce liverdamage resulting in bilirubinuria. Not only does the detection ofurinary bilirubin provide an early indication of liver disease, but alsoits presence or absence can be used in determining the cause ofclinical jaundice. this determination can be even more significant

when bilirubin results are combined with urinary urobilinogen.Jaundice due to increased destruction of red blood cells does notproduce bilirubinuria. This is because the serum bilirubin is presentin the unconjugated form and the kidneys cannot excrete it


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D.D. of jaundice


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Nitrite

CLINICAL SIGNIFICANCE

The reagent strip test for nitriteprovides a rapid screening testfor the presence of urinary tractinfection (UTI). The test is

designed to detect those casesin which the need for a culturemay not be apparent and is notintended to replace the urineculture as the primary test fordiagnosing and monitoring

bacterial infection.


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Urine Microscopy

Clean, mid-stream sample needed.

Cells & Casts & crystals

White cells – 10 or more WBC’s per cm3 indicates inflammation (e.g. urinary

tract infection (UTI))Red cells – again, subject may be aware of it already viapain.

Casts

– Cylindrical bodies made from precipitated proteins, often seennormally after exercise.

– Red cell casts (even one) always means disease.

Bacteria – allows you to decide which antibiotic is bestfor subject. Checking for blood/urine not always good for

checking for infections, since these subjects can havecompletely clear urine.


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Cells


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Casts


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Differential casts


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Crystals

urine analysis lecture 9&10

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