Routine urine analysis

The urinalysis is a routine screening test which is usually done as a part of a physical examination, during preoperative testing, and upon hospital admission. It is used in the diagnosis of infections of the kidneys and urinary tract and also in the diagnosis of diseases unrelated to the urinary system. The urinalysis consists of several components including: appearance, bilirubin, blood, color, glucose, ketones, leukocyte esterase, nitrites, odor, pH, protein, specific gravity, urobilinogen, and microscopic examination of sediment (bacteria, crystals, epithelial casts, fatty casts, granular casts, hyaline casts, red blood cells and casts, white blood cells and casts).

Urine Formation In the normal adult, approximately 1200 mL of blood perfuses the kidneys each minute, which accounts for about 25% of the cardiac output. The glomeruli (normally numbering at least 1 million per kidney) receive blood through afferent arterioles, and an ultrafiltrate of the plasma passes through each glomerulus into Bowman's space. From here the filtrate is passed through the tubules and collecting ducts where reabsorption or secretion of various substances and the concentration of urine can occur. This urine formed in the kidneys passes from the collecting ducts into the renal pelvis, ureters, bladder, and urethra to be voided.

The kidneys take part in several regulatory functions. eliminated waste products from the body, including nitrogenous products of protein catabolism, and both organic and inorganic acids and bases. Regulate Fluid, electrolytes (including sodium, potassium, calcium, and magnesium), and acid– base. provide important hormonal regulation with erythropoietin and renin production, as well as vitamin D activation.

Urine sample RANDOM SPECIMEN: A random urine specimen is satisfactory for most qualitative tests and may be collected at any time. FIRST MORNING : A first morning sample is collected when the patient rises in the morning. It is the most concentrated of the urine samples and is used for qualitative analysis. TWO-HOUR POSTPRANDIAL: This specimen is collected two hours after the patient has eaten a meal, the specimen is tested for glucose. TWENTY-FOUR HOUR SPECIMEN : The 24-hour specimen is made up of the total urinary output for a specific 24- hour period and to obtain an accurate timed specimen.

SPECIAL METHODS OF URINE COLLECTION Catheterization : is used for some bacteriological tests performed on urine. Midstream Specimen. Suprapubic Aspiration: Urine may be collected by external introduction of a needle into the bladder.

PRESERVATION Refrigeration. up to 8 hours is refrigerator at 4-6ºC. Toluene: used If only the chemical contents of the urine are of interest, it lies on the surface of the urine, forming a thin layer and acting as a physical barrier to air and bacteria. 10 % Formalin : is an excellent preservative for the formed (microscopic) elements in urine. 8% Boric Acid : Boric acid is used for general purposes. It will not interfere with examinations for protein, sugar, or ketone bodies. Chloroform. used as a preservative, but it interferes with some chemical tests and may cause cellular changes. Sodium Carbonate. To preserve urobilinogen in urine requires special precautions.

MACROSCOPIC AND PHYSICAL EXAMINATION OF URINE

Urine volume N.R: 1-2 L/24-h by normal adult. Polyuria . increase in the total volume of urine excreted more than 2 L/24-h. Oliguria. A reduction in the total volume of urine excreted less than 200 ml/24-h. Anuria. This term literally means "no urine" and refers to a complete lack of urine excretion.

Urine color The color of normal urine is caused by the presence of various pigments, which are collectively referred to as urochrome. Yellow. Normal urine has a color of straw, yellow, or amber. Green and Blue-Green. e.g. Oralcontraceptives, Bile pigment. Brown and Black. E.g. Porphyrins. Bilirubin. Red, Pink, or Reddish-Orange. E.g. Beets. Food colors. Blood. Hemoglobin.

General appearance of the urine Clear. Normal, freshly voided urine is usually clear as it has no visible particles. Hazy. When the sample contains a small amount of particles, it is designated as hazy. Cloudy. Moderate to large amounts of visible particles produce a cloudy urine.

Specific gravity Specific gravity is a comparison of the density of urine to the density of distilled water, which is regarded as 1.000. Normal Values Adult: 1.005–1.030 (random sample usually 1.015–1.025)

pH The usual pH is about 6.0, with a reference range of 4.6 to 8.0.

Urine odor Fresh urine from a healthy patient usually has a very slight aromatic odor, which is due to certain volatile constituents.

CHEMICAL TESTS FOR SUBSTANCES IN URINE PROTEIN : Normal Values: Negative GLUCOSE: Normal Values: Negative KETONES: Normal Values: Negative UROBILINOGEN: Negative or 0.1–1.0 Ehrlich units/dL leukocyte esterase and nitrites: Normal Values: Negative

THE MICROSCOPIC EXAMINATION OF URINARY SEDIMENT Methodology A sample of well-mixed urine (usually 10-15 ml) is centrifuged in a test tube at relatively low speed (about 2- 3,000 rpm) . 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 poured onto a glass slide and coverslipped.

Red Blood Cells WBCs

Epithelial cells Casts

Crystals

Yeasts Parasites