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Captopril Information and Courses from MediaLab, Inc.

These are the MediaLab courses that cover Captopril and links to relevant pages within the course.

Learn more about laboratory continuing education for medical technologists to earn CE credit for AMT, ASCP, NCA, and state license renewal and recertification. Or get information about laboratory safety and compliance courses that deliver cost-effective OSHA safety training and continuing education to your laboratory's employees.



Chemical Screening of Urine by Reagent Strip
False Positive and Negative Ketone Results

False Positive KetonesFalse positive ketone results may be seen in patients after BSP or PSP dye injection due to the phthaleins. The presence of L-DOPA metabolites, some urine preservatives (e.g. 8-hydroxyquinaline), or high levels of phenylketones will also cause false positive results. Antihypertensive drugs such as methyldopa and captopril also may produce false positive results.False Negative KetonesThe presence of excess moisture/humidity can cause the ketone reagent to become nonreactive, resulting in a false negative test for ketones. Urine specimens should not remain at room temperature if testing is delayed because ketones are unstable at room temperature.

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False Positive and Negative Results

False Positives:A false positive result for blood on the urine chemical reagent strip can occur when oxidizing contaminants, such as hypochlorite (bleach), remain in collection bottles after cleaning. Contamination of the urine with provodine-iodine, a strong oxidizing agent, used in surgical procedures can also result in a false positive reaction. Microbial peroxide found in association with urinary tract infections may also cause false-positive results. Capoten® (Captopril) can cause decreased reactivity.The muscle tissue form of hemoglobin, myoglobin is a well-known cause of false-positive reactions on the blood portion of the reagent strip. When tissue hemoglobin is present, the urine specimen has a clear red appearance. Patients suffering from muscle-wasting disorders or muscular destruction due to trauma, prolonged coma, or convulsions or individuals engaging in extensive exertion may have myoglobin in their urine. Specific tests for myoglobin, such as immunodiffusion techniques or protein electrophoresis, are needed to confirm the presence of this substance in a urine specimen. Levels of ascorbic acid normally found in urine do not interfere with this test. False Negatives:False negative results may occur in some analysis methods when the concentration of ascorbic acid is greater than 5 mg/dL. The sensitivity of the blood portion of the test strip is decreased in specimens with a high specific gravity and increased protein. High levels of nitrites may delay the reaction, causing a false negative to be reported. If the pH of a urine sample is below 5, hemolysis of red cells as part of the test reaction is inhibited which results in a false negative reaction. An improperly mixed specimen may test negative if the red blood cells are in the sediment.

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Chemical Screening of Urine by Reagent Strip (retired March 2012)
False Positive Ketone Results

False positive ketone results may be seen in patients after BSP or PSP dye injection due to the phthaleins. The presence of L-DOPA metabolites, some urine preservatives (e.g. 8-hydroxyquinaline), or high levels of phenylketones will also cause false positive results. Antihypertensive drugs such as methyldopa and captopril also may produce false positive results.

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False Positive Results

A false positive result for blood on the reagent strip can occur when oxidizing contaminants, such as hypochlorite (bleach), remain in collection bottles after cleaning. Contamination of the urine with provodine-iodine, a strong oxidizing agent, used in surgical procedures can result in a false positive reaction. Microbial peroxide found in association with urinary tract infections may also cause false-positive results. Capoten® (Captopril) can cause decreased reactivity. The muscle tissue form of hemoglobin, myoglobin is a well-known cause of false-positive reactions on the blood portion of the reagent strip. When tissue hemoglobin is present, the urine specimen has a clear red appearance. Patients suffering from muscle-wasting disorders or muscular destruction due to trauma, prolonged coma, or convulsions or individuals engaging in extensive exertion may have myoglobin in their urine. Specific tests for myoglobin, such as immunodiffusion techniques or protein electrophoresis, are needed to confirm the presence of this substance in a urine specimen. Levels of ascorbic acid normally found in urine do not interfere with this test.

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