ACTIVITY 9ACTIVITY 9URINALYSISURINALYSIS

Medical Physiology Lab.

Urinalysis Urinalysis A urinalysis is a group of manual A urinalysis is a group of manual

and/or automated qualitative and and/or automated qualitative and semi-quantitative tests semi-quantitative tests performed on a urine sample.performed on a urine sample.

It is a test that checks many It is a test that checks many body functions in one exam. body functions in one exam.

Once you know what to look for, Once you know what to look for, you can see what’s going on with you can see what’s going on with various systems.various systems.

PurposePurpose

Routine urinalyses are performed Routine urinalyses are performed for several reasons:for several reasons:

1. general health screening to detect 1. general health screening to detect renal and metabolic diseases. renal and metabolic diseases.

2. diagnosis of diseases or disorders 2. diagnosis of diseases or disorders of the kidneys or of the kidneys or

urinary tract. urinary tract. 3. monitoring of patients with 3. monitoring of patients with

diabetes. diabetes.

Functions of kidney:Functions of kidney:The human kidneys have four major functions. The human kidneys have four major functions.

They are to:They are to:

1.1. Remove metabolic waste and toxins from the Remove metabolic waste and toxins from the body.body.

2.2. Regulate the volume and composition of the Regulate the volume and composition of the

body fluids through secretion and reabsorption.body fluids through secretion and reabsorption.

3. 3. Maintain the balance of acids to bases in the Maintain the balance of acids to bases in the

body (i.e., pH).body (i.e., pH).

4.4. Produce metabolites such as renin and vitamin Produce metabolites such as renin and vitamin

D that are important to other body tissues andD that are important to other body tissues and

cells.cells.

Physical Characteristics Physical Characteristics of Urine:of Urine:1. Color1. ColorNormal = pale yellow due to a pigment called

urochrome.Color is associated with solute concentration.

Increased solutes = darker urine;Decreased solutes = colorless urine, like

water.Solute concentration is measured using a

urinometer to determine specific gravity.Specific gravity of water = 1.000Specific gravity of normal urine = 1.001 to

1.030

ColorColor

2. Transparency2. TransparencyNormal = clearAbnormal = cloudy, which may

be caused by bacteria, blood, cells, crystals, etc.

3. Odor3. OdorNormal = slightly aromatic when

freshly voided.Bacteria = ammonia odorAsparagus, drugs and diseases

my also impart a characteristic odor.

Diabetes mellitus = urine smells "fruity" or like acetone.

4. pH4. pHNormal pH = 4.5 to 8.0 (average

is about 6.0)High protein diet = acid urineVegetarian diet = alkaline urine

5. Specific gravity5. Specific gravityNormal = 1.001 to 1.030.Low Specific Gravity may be due to:1.Excess fluid intake2.Use of diuretics3.Diabetes insipidus4.Chronic renal failureHigh Specific Gravity may be due to:1.Low fluid intake2.Fever3.Pyelonephritis

Excessively concentrated urine may lead to kidney stones (renal calculi), that are made of crystals of salts that are present in urine such as uric acid, calcium oxalate or calcium phosphate.

Decreased water intake and increased calcium intake may also cause kidney stones.

Normal Constituents of Normal Constituents of UrineUrineWaterUreaSodium and potassiumPhosphate and sulfate ionsCreatinineUric acidCalciumMagnesiumBicarbonate ions

Abnormal Constituents of Abnormal Constituents of UrineUrineGlycosuria = glucoseHematuria = Red blood cellsPyuria = White blood cellsBacteriuria = bacteriaKetonuria = ketones

Terminology of Urine Terminology of Urine OutputOutputPolyuria = excessive production of urine

Anuria = decreased production of urine

Dysuria = painful urination

Urinary Disorders:Urinary Disorders:Diabetes mellitus = decreased

production or utilization of insulin. (Ketonuria with glycosuria is usually diagnostic for diabetes mellitus).

Diabetes insipidus = large amounts of dilute urine is excreted, usually 5-20 liters per day.◦Caused by inadequate secretion of

antidiuretic hormone (ADH).UTI = bacterial infection of the urinary

tract.

Urethritis = inflammation of the urethra

Cystitis = inflammation of the urinary bladder

Pyelonephritis = inflammation of the kidneys

Glomerularnephritis = inflammation of glomeruli in kidneys

Acetonuria = ketone bodies in the urine

Azotemia = presence of urea in the blood

Enuresis = bed wetting

Nephrotic syndrome = protein in the urine due to increased permeability of the glomerular capillary endothelium

Cystocele = hernia of the urinary bladder

Polycystic kidney disease = most common inherited disorder of the kidneys

Nephrotosis = floating kidneyMicturition = urination

Urine Dipstick:Urine Dipstick:

Each of the squares corresponds to something being tested.

You are supposed to compare the colors of each square to a suggested color on the box to determine if things are normal.

1. Glucose1. GlucoseRenal threshold for glucose is

such that after a certain point is reached, the glucose spills over. The specific threshold level depends on the patient. Even within an individual, the personal threshold varies daily.

Therefore the dipstick test for glucose is really inaccurate.

2. Ketones2. KetonesProduced from fatty acids.a.Causes of ketones in the urine are starvation

and diabetes mellitus, ketoacidosis, etc.b.Two major ketones in the body

Beta hydroxybutyric acid Acetoacetate

The dipstick test is non-specific and only sensitive to the second type of ketone (acetoacetate).

If you do a dipstick test, and it comes back ketone +, perform a serum ketone level because something is definitely going wrong.

3. Blood in the urine:3. Blood in the urine:Two situationsa.HEMOGLOBINURIA = blood in the

urine but the red blood cell (RBC) are NOT intact. The cause is hemolysis.

b.HEMATURIA = intact red blood cells in the urine. This points to the urinary tract as the source of the problem.

Kidney Ureter Bladder

4. Protein:4. Protein:a. Proteins are NOT supposed to

be in the urineb. Prevention of proteins into the

urine is done by glomerular membrane.

5. Bilirubin:5. Bilirubin:NOT supposed to be in the urine

6. Urobilinogen:6. Urobilinogen:Grade this from 1 – 5 (5 being the

highest)a. with high RBC destruction

7. Nitrates:7. Nitrates:Made by many bacteria species (with

the exception of Staph & Strep)a. e.g. E. coli, Proteus, Pseudomonas

etc.b. If nitrate +, urinary tract infection is

suggested (UTI)c. a – test does NOT rule out a UTI

8. Leukocyte esterase: 8. Leukocyte esterase: enzymeenzymeWhite blood cell (WBC) in urine

noted by implicationThe enzyme esterase is normal in

urine+ for this enzyme then probably

a UTI

9. Casts: 9. Casts: Lots of different material clumped

together inside of the renal tubule.a.As a general rule if a cast is present,

then something is going on.b.Exception to the above rule is if you

see a hyaline cast, which is a normal finding.

c.Clumped cells come from the kidneyd.Casts can be RBC or WBC casts

a. If you see these in the urine, tells you that there is a disease from the bladder kidney (moving up).

Casts If you see RBC – kidney problem

◦Could be: Pyelonephritis SLE Kidney stones Trauma (e.g. hit in the flank/abdomen)

If you see WBC casts – probably due to infection.

10. Crystals:10. Crystals:

a. Very small amount is normalb. Could be due to gout or liver

disease

11. Bacteria: ◦urine is considered sterile, therefore

bacteria in the urine is not normal◦If + for bacteria, probably due to a

UTI.

Microscopic Analysis of urine Microscopic Analysis of urine sedimentsedimentUnorganized sediments – chemical

substances that form crystals or precipitate from solution.◦ Calcium oxalates, carbonates and phosphates;◦ Uric acid◦ Ammonium urates◦ Cholesterol

Crystals are frequently found in the urine. They are formed by the precipitation of urine salts subjected o changes in pH, temperature or concentration, which affect their solubility. Crystals are identified by their appearance, solubility and pH.

Organized sediments Organized sediments – Epithelial cells, WBC, RBC, casts.Cells can be anywhere in the urinary

tract from the tubules to the urethra.Casts are cylindric structures formed

primarily within the lumen of the distal convoluted tubule and collecting duct. The major constituent of casts is Tamm-Horsfall protein, a glycoprotein excreted by the renal tubular cells.

Normal – negative