CMDT 2007 URINAYLYSIS

CMDT 2007

Page 957 DIPSTICK URINALYSIS

PH: There is no role for dipstick urinalysis screening for urinary tract disorders in asymptomatic adults except for pregnant women.

Protein: Dipsticks using bromphenol blue can detect protein in concentrations exceeding 10 mg/dl. It measures albumin and is not sensitive for the light chain of immunoglobulins (Bence Jones proteins). False-positives results are seen in urine containing numerous leukocytes or epithelial cells.

Glucose and Ketones: Only small amounts of glucose are normally excreted in the urine, and these levels are below the sensitivity of the dipstick. Any positive finding requires evaluation for diabetes. The test is specific for glucose and does not cross-react with any other sugars. Ascorbic acid or elevated ketones may result in false-negative results.
Ketones are not normally found in the urine, but fasts, post exercise states, and pregnancy may result in elevated urinary ketones. Diabetics often demonstrate elevated urinary ketones levels prior to an elevation in serum levels. False-positive results occur in dehydration or in the presence of levodopa metabolites, mesna (sodium mercaptoethanesulfonate), and other sulfhydryl containing compounds.

Nitrites: Normally, the urine does not contain nitrites. Many gram-negative bacteria can reduce nitrate to nitrite, which is thus an indicator of bacteriuria. However, the low sensitivity of the test requires clarification. Adequate numbers of bacteria must be present (10^5 organisms/mL), nitrates must be available in the urine, and the bacteria must be in contact with the urine for a sufficient time (usually 4 hours). Therefore, the first morning voided sample is preferable. False-negative results may be due to non-reducing organisms, frequent urination, dilute or acidic urine (pH<>Gram staining may further aid in characterizing the organism).

Page 158 Microscopic Urinalysis

Bacteria and Yeasts: The identification of organisms in an uncontaminated specimen implies infection, which must be confirmed by culture. The presence of several organisms per high power field usually correlates with a culture count of 10^5 organisms per milliliter. Gram staining maybe further aid in characterizing the organism. …For yeast, colony count per milliliter does not necessarily correlate with the severity of infection.

PAGE 36 Urine Culture

Urine Culture: Urine culture should be considered for all women with upper tract symptoms (prior to initiating antibiotic therapy), as well as those with dysuria and a negative urine dipstick test. In symptomatic women, a clean-catch urine culture is considered positive when 10^2-10^3 colony-forming units/mL of a uropathogenic organism is detected.

*Now adays a culture is negative at a cut off of 10^5. They do not ask in the lab the variables of the person who the sample is taken from. Not to mention the nursing staff doesn't think it matters.

Page 957 COLLECTION OF SPECIMENS

Just talks on how to take a specimen from a male. Nothing about the 4 hour rule.

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So, they take urine that hasn't been in my bladder for more than 20 minutes to an hour. Then charge me for a urinalysis, microscopic and/or a culture. Whereupon giving false readings due to the lack of diligence upon the part of the staff to see to it that the correct sample is taken. Like a 24 hour sample. Lately, they don’t even do a clean catch.