Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1275 page)

   
Color:
The color of the specimen is measured by comparison to four known wavelengths of light (red, violet, blue, and green), which are used to determine the color and hue of the sample.

   
Clarity:
The clarity or turbidity of the urine specimen is measured by passing a light beam through the sample and measuring the scattered light. The amount of scattered light increases as the specimen becomes more turbid. Clarity is reported as clear, turbid, or extremely turbid.

   
pH:
Along with the lungs, the kidneys are the major regulator of acid– base balance. pH testing provides valuable information for assessing and managing disease and determines the suitability of a specimen for chemical testing. Freshly voided urine has a pH of 5.0–6.0. The pH of urine can be controlled by dietary regulation and medication.

   
Glucose:
Glucosuria is usually indicative of hyperglycemia due to diabetes but can also be seen in patients with other causes for hyperglycemia, in patients with renal tubular dysfunction, and in pregnancy due to increased glomerular filtration. In children especially younger than 2 years of age, it is important to perform a screening test for reducing sugar.

   
Protein:
The presence of protein in urine is mostly indicative of renal disease, but its appearance in the urine does not always signify renal disease. The strip is primarily sensitive to albumin.

   
Bilirubin:
The appearance of urinary bilirubin can be a sign of liver disease or extrahepatic or intrahepatic biliary obstruction.

   
Urobilinogen:
The normal urine has a small amount of urobilinogen. Increased amounts appear in hemolytic anemias and liver dysfunction.

   
Blood:
Equally specific for RBCs, Hb, or myoglobin present in the urine. Hematuria can be seen due to bleeding as a result of trauma or irritation. Hemoglobinuria occurs when there is lysis of RBCs in the urinary tract, intravascular hemolysis, or transfusion reactions. Very dilute or extremely alkaline urine can also lyse the cells. Myoglobinuria indicates muscular destruction that may appear in hypothermia, convulsions, and extensive exertions.

   
Ketones:
Ketonuria appears when there is an increased use of fat instead of carbohydrate for metabolism. Conditions of ketonuria include DM, vomiting, and inadequate intake of carbohydrates due to starvation or weight reduction, or pregnancy.

   
Nitrite:
Bacteria, specifically gram-negative bacteria, are detected. This analysis provides a rapid and economical means of detecting significant bacteriuria caused by nitrate reducing bacteria. It is limited by various factors, including characteristics of microorganisms, dietary factors, urinary retention time, and specimen storage.

   
Leukocytes:
The presence of WBCs is an indicator of inflammation; lysed and intact WBCs are detected.

   
Normal range:
see Table 16.81.