A complete urinalysis consists of visual, chemical and microscopic examinations. Visual examination includes color, volume, odor and specific gravity. Normal urine is of pale yellow color. In pathology, color varies – red in glomerulonephitis or kidney trauma (blood in the urine), dark yellow in jaundice (when serum bilirubin and its associated metabolites are elevated), no color in diabetes mellitus (due to low gravity). Some medicines (antibiotics may turn urine into red) or other conditions (dietary deviations with beet) change the color of urine. The urine must be clear; it is cloudy in cases of pyelonephritis and cystitis. Normally, an adult human produces 600-1800 ml of urine per 24 hours, depending on the diet pattern and environmental conditions. Oliguria is a urine, less than 1ml/h, and anuria – less than 0.5ml/h. These conditions of low urine output may be pre-renal in origin (heart failure, massive blood loss), renal (glomerulonephritis, trauma) or post-renal (urethra obstruction, kidney stones blocking output). Odor is caused by ammonia from wastes that urine excretes from the body. Sweet odor indicates ketonuria (suggesting diabetic decompensation), feces odor means infection (probably due to E.coli contamination). Specific gravity depends on daily fluid intake, time of sample collection and age. Low gravity suggests diabetes or poor kidney function (inability to concentrate urine), while high gravity indicates proteinuria, erythrocyturia or leucocyturia.
Chemical examination determines ketonuria, pH, blood, bilirubin, glucose, protein, nitrite, phenylketones, chorionic gonadotropin and nucleic acids. Ketone bodies strongly suggest severe deviations of carbohydrates metabolism as in diabetes, starvation or metabolic acidosis (in advanced vomiting). The pH index is a negative log of proton ions. Low pH (<5.0 for urine) indicates systemic acidosis (since the organism evacuates protons into the urine) or phenylketonuria. High pH (>8.0 for urine) indicates systemic alkalosis (since the organism reabsorbs protons back from the urine) or infection (bacteria produces alkaline environment). Hemoglobin suggests trauma or glomerulonephritis (membrane barrier is damaged and blood from the vessels enters the urine). Biliribin and its derivatives are good indicators of liver malfunction (like cirrhosis) or red blood cells destruction. Glucosuria is an indicator of diabetes and predictor of its severity. Proteins in the urine suggest renal disease and arterial hypertension (similar mechanism as for the blood in the urine) but may occur normally in the pregnant. Bacteria waste products are nitrites and its contamination suggests infection. Phenylketones are amino acid derivatives that have to be screened in order to detect severe metabolism disorders.in the newborn Chorionic gonadotropin is a hormone that indicates pregnancy. Since this is a small protein, it is easily excreted into the urine and can be used for early pregnancy detection. Nucleic acid is a universal genetic material, so when microorganisms (bacteria or virus) are present, their nucleic acids can be traced to diagnose a sexually transmitted disease.
Microscopic examination reveals cells, casts, crystals, bacteria, and parasites. Red blood cells in the urine suggest stones (mechanical microtrauma), trauma or infection; white blood cells suggest infection (pyelonepohritis or cystitis); epithelium is indicative for infection. Casts state for degenerative process in the kidneys. Crystals usually reflect diet pattern or stones. Bacteria and parasites suspect infection.