Urine tests / urinary

Diazomethane is often used to esterify polar or reactive compounds for mass spectrometry analysis. For example, a urine test for cocaine might involve treating the sample with diazomethane to convert benzoylecgonine, the major urinary metabolite of cocaine, to its volatile methyl ester for MS analysis. 

Richards D, Toop L, Chambers S and Fletcher L (2005) Response to antibiotics of women with symptoms of urinary tract infection but negative dipstick urine test results double blind randomised controlled trial. British Medical Journal 331(7509) 143. 

Changes in the erythrocyte zinc concentration were slow to appear as expected on the other hand, changes In the leukocyte zinc concentration appeared more sensitive to changes In zinc intake. Urinary excretion of zinc decreased as a result of dietary zinc restriction, suggesting that renal conservation of zinc may be Important for the homeostatic control mechanism in man. Thus, measuring zinc concentration in a 24-h urine test may be of additional help in diagnosing zinc deficiency provided cirrhosis of the liver, sickle cell disease, and chronic renal diseases are ruled out. These conditions are known to have hyperzlncuria and associated zinc deficiency. 

This may be found by routine urine testing of pregnant women or patients with known structural abnormalities of the urinary tract. Such infection may explain micturition frequency or incontinence in the elderly. Appropriate antimicrobial therapy should be given, chosen on the basis of susceptibility tests, and normally for 7-10 days. Amoxicillin or a cephalosporin is preferred in pregnancy, although nitrofurantoin may be used if imminent delivery is not likely (see below). 

Siemens DR, Morales A, Johnston B, et al. A comparative analysis of rapid urine tests for the diagnosis of upper urinary tract malignancy. Can J Urol 2003 10 1754-58. 

Fitzgerald RL, Ramos JM Jr, Bogema SC, Poklis A. Resolution of methamphetamine stereoisomers in urine drug testing Urinary excretion of R( )-methamphetamine following use of nasal inhalers. J Anal Toxicol 1988 12 255-9. 

As over 90% of the body s iodine is excreted in urine, urinary excretion of iodine is currently the most commonly-used biochemical marker of iodine intake. The determination of urinary iodine excretion in 24-h urine specimens is considered to be the most reliable method (Dunn, 1993) for testing urinary iodine levels. However, the accuracy and validity of the results will depend on the completeness of the 24-h collections hence, measures to assess the completeness of such collections, e.g., urinary creatinine excretion or para-aminobenzoic acid (Gibson, 2005), should be considered. 

When a UTI has been diagnosed, sensitivity tests are performed to determine bacterial sensitivity to the drugp (antibiotics and urinary anti-infectives) that will control the infection. The nurse questions the patient regarding symptoms of the infection before instituting therapy. The nurse records the color and appearance of the urine. The nurse takes and records die vital signs. A urine sample for culture and sensitivity is obtained before the first dose of the drug is given. 

A recent method to screen the urine for alkyl phosphates as an indicator of exposure to organophosphate insecticides shows that the method can be used to determine environmental exposure to a specific organophosphate pesticide. The method was found to be sensitive, identifying low levels of exposure to insecticides in the environment by quantitation of urinary phosphates (Davies and Peterson 1997). The test is limited in that it is only useful for assessing recent exposure, due to the short half-life of the organophosphate pesticides. 

If the test is positive, the urine is examined microscopically for red blood cells. If no red blood cells are found, a tentative diagnosis of myoglobinuria is made, serum chemistries are obtained, and the patient is held to rule out rhabdomyolysis. If the uric acid and creatinine kinase (CK) values are normal, and the patient is asymptomatic, he/she is discharged from the hospital. Routine toxicology tests include urinary PCP, serum alcohol, and hypnotic screen. 

Urinary excretion of radioactivity was measured in human volunteers during and after a 3.5-hour period of dermal exposure to 0.11 or 0.22 g 32P-labeled TOCP (Hodge and Sterner 1943). The specific activity of the test substance was not reported. Radioactivity in urine was measured with a Geiger-Muller counter, but the limits of detection were not reported. Maximum estimated excretion rates, 10 and 43 pg TOCP/hour for the respective dosage levels, were measured within 24 hours of initiation of exposure. Radioactivity was not detected 48 or 72 hours after dosing ceased. Cumulative radioactivity detected in urine accounted for 0.13% and 0.36% of the dermally applied radioactivity. 

In the case of life-threatening hydrogen sulfide poisoning, measurements of blood sulfide or urinary thiosulfate levels may be used to confirm exposure. However, samples need to be taken within two hours of exposure in order to be useful. The tests for measuring sulfide in the blood or thiosulfate in the urine are described in Section 2.7.1. 

For UUI, the preferred diagnostic tests are urodynamic studies. Urinalysis and urine culture should be performed to rule out urinary tract infection. 

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