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The presence of ureasplitting organisms that convert urea to ammonia may cause urine to become more alkaline.

(Wilson 2005)

Preprocedural considerations

Equipment

Dipstick (reagent) tests

Strips that have been impregnated with chemicals are dipped quickly in urine and read. When dipped in urine, the chemicals react with abnormal substances and change colour. Although dipstick reagents have been primarily used as screening tools for protein or glucose in the urine, more sophisticated reagents are now available. These reagents test for nitrites and leucocyte esterase as indicators of bacterial infection. Leucocyte esterase is an enzyme from neutrophils not normally found in urine and is a marker of infection. Nitrites are produced by the bacterial breakdown of dietary nitrate, which is a waste product of protein metabolism (Rigby and Gray 2005). It is essential to use the strips according to the manufacturer’s instructions and be aware of factors that may affect the results, including specific drugs (Table 12.7), the quality of the urine specimen itself and the possibility of falsenegative results.

Table 12.7 How drugs may infl uence the results of reagent sticks

Drug Reagent test Effect on the results

Ascorbic acid Glucose, blood, nitrite High concentrations may diminish colour

LDopa Glucose High concentrations may give a falsenegative reaction

Ketones Atypical colour

Nalidixic acid Urobilinogen Atypical colour – probenacid

Phenazopyridine (pyridium) Protein May give atypical colour

Ketones Coloured metabolites may mask a small reaction

Urobilinogen, bilirubin May mimic a positive reaction

Nitrite

Rifampicin Bilirubin Coloured metabolites may mask a small reaction

Salicylates (aspirin) Glucose High doses may give a falsenegative reaction

Specific patient preparations

Education

Most patients need advice on hygiene and technique before the procedure to prevent contamination from hands or the genital area (Higgins 2008) and to ensure that the midstream sample is collected correctly. Midstream urine specimens are indicated in adults and children who are continent and can empty their bladder on request (Gilbert 2006).

Procedure guideline 12.7 Urinalysis: reagent strip procedure

Essential equipment

Nonsterile disposable gloves

Apron

Urine dipsticks, that are in date; make sure they have been stored according to the manufacturer’s recommendations

Appropriate urine specimen pot

Preprocedure

Action Rationale

1 Explain and discuss the procedure with the patient. To ensure that the patient understands the procedure and gives their valid consent (NMC 2008b, C).

2 If taking the specimen from a urinary catheter it should be collected using an aseptic technique. To avoid contamination (Fraise and Bradley 2009, E).

3 Wash and dry hands and put on gloves and apron. To maintain infection control and prevent crossinfection (Fraise and Bradley 2009, E).

Procedure

4 Obtain clean specimen of fresh urine from patient. Urine that has been stored deteriorates rapidly and can give false results (Bayer Diagnostics 2006, C).

5 Check reagent sticks have been stored in accordance with manufacturer’s instructions. This is usually a dark dry place. Tests may depend on enzymic reaction. To ensure reliable results (Bayer Diagnostics 2006, C).

6 Dip the reagent strip into the urine. The strip should be completely immersed in the urine and then removed immediately. Run edge of strip along the container. This will remove excess urine and prevent mixing of chemicals from adjacent reagent areas. To remove any excess urine (Bayer Diagnostics 2006, C).

7 Hold the stick at an angle. Urine reagent strips should not be held upright when reading them because urine may run from square to square, mixing various reagents (Bayer Diagnostics 2006, C).

8 Wait the required time interval before reading the strip against the colour chart (see Action Figure 8). The strips must be read at exactly the time interval specified or the reagents will not have time to react, or may be inaccurate