Lab 9 (PART 2) Urinalysis Testing

Composition of Urine

Each day the kidneys purify approximately 150-180 litres of plasma, resulting in the production of 1-1.8L of urine daily. The volume produced is influenced by many factors, including environmental temperature, time of day, and fluid intake.

Urine is 95% water and 5% dissolved substances. A thorough urinalysis (a combination of macroscopic and microscopic examination of urine) can provide much information about the general condition of the body. A macroscopic urinalysis involves observation of characteristics that can be detected without the aid of a microscope: appearance, odor, specific gravity, and pH. All of these, except specific gravity, will be reviewed in this lab.

Normal volume: 800-2000L/24hrs

Macroscopic Analysis: Color and clarity

Color: A normal sample is often yellow in color, ranging from pale to dark amber. The presence of blood will produce a red color urine, whereas bilirubin can cause the sample to appear yellow-brown or green-brown. Abnormal colors can result from eating certain foods.

Clarity: this is a measure of how clear the sample appears. A normal sample can be clear or cloudy. Cloudiness in a healthy patient may be due to the presence of mucus, sperm, epithelial cells, crystals, or surface contaminants such as body powder. Abnormal constituents of urine can also cause cloudiness. They may include bacteria, red and/or white blood cells.

Macroscopic analysis: Specific Gravity, pH, and Odor

Specific Gravity: this is a test of how concentrated the urine sample is

pH: urine is slightly acidic around 6, but can range from 4.5-8, depending on diet, medications, and metabolic status of the individual. Various crystals will precipitate out at certain pH levels, which may reduce their ability to be eliminated from the body.

Odor: A strong odor is not typical; can be influenced by diet, medications, metabolic status, pregnancy, a urinary tract infection, or dehydration.

Microscopic Urinalysis

A microscopic urinalysis involves observation of the materials found in urine with the aid of a microscope. Urine consists of organic and inorganic substances in aqueus solution. Substances in normal urine are waste products from cellular metabolism and products derived from certain ingested foods. Substances not normally present in urine can indicate pathological conditions. Two types of sediments can be found in urine: Organized sediments and Unorganized sediments

Organized sediments

Cells and casts. Cells such as epithelial cells, erythrocytes, leukocytes may be seen in urine. As well, casts, cylindrical structures constructed by the precipitation of protein and agglutination of cells within renal tubules may be seen. The presence of epithelial cells is normal; the presence of casts, erythrocytes, and leukocytes usually indicates a pathological condition.

Unorganized sediments

Crystals. Normal urine contains small amounts of crystals but large amounts may indicate a pathological conditions.

Cells epithelial and erythrocytes/leukocytes IN URINE significance

Epithelial: small amounts normal as exfoliated from urinary tract; large amounts indicate renal pathology or bacterial infection

Erythrocytes/leukocytes: pathology of urinary tract, inflammation

Casts in urine significance: Hyaline, Granular, Fatty, Waxy

Hyaline: most common type of cast; normal in small amounts; large amounts after vigorous exercise and if the person is dehydrated

Granular: 2nd most common cast; from breakdown of cellular casts; large amounts after vigorous exercise and if person has chronic renal disease

Fatty: from the breakdown of lipid-rich epithelial cells; a sign of high urinary protein nephrotic syndrome

Waxy: formed when urine is retained due to pathology of the kidney

Microbes in urine

Bacteria: Enter the urethra and the bladder from the skin causing UTIs. Untreated, infection can spread to the kidneys.

Yeasts: More likely if a vaginal yeast infection has occured

Parasites: Trichomonas vaginalis in urine due to contamination during a vaginal inflection

Crystals: Calcium oxalate, uric acid, triphosphate, calcium phosphate

calcium oxalate (monohydrate form looks like dumbells, dihydrate form looks like octahedral): after eating asparagus, spinach, rhubarb and garlic; present in ethylene glycol poisoning (dehydrate form) and diabetes.

Uric acid: abnormal results from purine metabolism; levels elevated with gout and chronic nephritis

Triphosphate (struvite): normal in low levels, large amounts over time may indicate stones or chronic urinary tract infection

Calcium phosphate: normal in low levels, elevated levels may indicate stone formation

Crystal types: Cystine, Hippuric acid, Cholesterol, Calcium Carbonate

Cystine: abnormal, indicates pathology or urinary tract or an inherited metabolic disorder

Hippuric Acid: normal, rarely seen; no clinical significance

Cholesterol: Abnormal, large amounts indicate increased levels in the blood; indicates Nephrotic Syndrome

Calcium Carbonate: Normal, normally found in alkaline urine

Crystal Images!!!!

REview

Abnormal constituents of urine: glucose and ketone bodies

Glucose: glucosuria is a condition where glucose is present in urine. It indicates an abnormally high blood glucose level. It may result from the intake of excessive amounts of carbohydrates that can cause a temporary rise in blood glucose or it may be due to uncontrolled diabetes mellitus

Ketone bodies: are produced when fats are broken down in the body. A diet low in carbohydrates, starvation, prolonged vomiting, or dehydration can also result in ketonuria. High levels of ketones indicate metabolic abnormalities. Coupled with glycosuria, these two conditions are used to confirm a diagnosis of diabetes mellitus.

Abnormal constituents of urine: Albumin

This is the most abundant protein in our blood and is too large to pass through the glomerular filtration membrane. Albuminuria indicates increased permeability of the glomerulus to the protein. Temporary increases in urine levels are common after excessive physical exertion, pregnancy, or elevated dietary intake of protein. Pathological conditions that result in albuminuria include physical trauma to the kidney, ingestion of heavy metals or poisons, bacterial toxins, hypertension, and inflammation of the glomeruli.

Abnormal constituents of urine: Nitrites, Billirubin, White blood cells,

Nitrites: nitrites discovered in urine are useful for detecting bacterial infections of the bladder

Billirubin: Low levels of bile pigments in urine are normal, giving it the characteristic yellow color. Elevated levels of bile (bilirubinuria) is an abnormal conndition and indicates some form of liver problem, such as hepatitis, cirrhosis, or bile duct blockage. It produces a yellow foam when the urine sample is shaken

White blood cells (leukocyturia: This indicates the presence of white blood cells or other components of pus (pyuria) in the urine. It indicates an inflammation in the urinary tract

Abnormal constituents of urine: Leukocyte esterase, Red blood cells, hemoglobin

Leukocyte esterase: This is an enzyme found in white blood cells. Testing is done to confirm the presence of a urinary tract infection, such as a bladder or kidney infection

Red Blood Cells: Red blood cells are not normally found in urine. Blood in the urine is associated with inflammation of the kidneys, bladder or urethra. Strenuous exercise can also result in blood in the urine

Hemoglobin: Hemoglobinuria indicates pathological problems such as hemolytic anemia, burns, poisonous snakes bites, renal disease, and transfusion reactions

Alone or in combination

Alone or in combination any one of these factors may alter the visual appearance and odor of a urine sample, making it appear cloudy, dark, or give it a peculiar odor. That too is of diagnostic value during urinalysis.

Biochemistry of renal function: Blood Urea Nitrogen, Creatinine, Electrolyte panel

Blood urea nitrogen (BUN): Urea iss a by-product of protein metabolism. Elevated levels indicate kidney malfunction and is seen in individuals with kidney disease, heart problems, or diabetes.

Creatinine: Produced by muscle tissue as it metabolizes creatine. Kidney function is assessed by how well it eliminates this compound over a 24-hour period.

Electrolyte Panel: Tests to measure sodium, potassium, chloride, and bicarbonate levels. Use to determine if the patient is suffering from dehydration, kidney disease, lung disease, or a heart condition.

Physical characteristic observations

observe and record the color, odor, and clarity of urine

Testing pH

Dip a pH strip into the simulated urine for the sample you have been assigned. Compare the color of the test strip to the comparator chart within 30 seconds of sampling.

Testing for protein

Biuret’s test

Using a plastic pipet transfer 2-3ml of assigned simulated urine into a test tube. Using a plastic pipet transfer 2-3ml of Biuret solution to the urine and swirl the tube. Note the color of the solution. A positive reaction will result in an orange-red color….negative will five a green color

Testing for glucose

Using a plastic pipet transfer 2-3ml of the assigned simulated urine sample into a test tube. Using a plastic pipet add 2-3ml of Bennedict’s solution swirl the tube and note the color of the solution. Place tube in hot water bath for 5 minutes. Remove the sample from the hot water bath. Slight red-orange color change at bottom of tube is a positive reaction… an overall green color is a negative reaction