• Choose a category
• All
• Classic-Fiction

By Root 1657 0

2010). The composition of urine can change dramatically as a result of disease, and abnormal substances may be present. Urinalysis can identify many of these substances, and should be part of every physical assessment (Cook 1996, Torrance and Elley 1998).

Evidencebased approaches

Rationale

Urinalysis (urine testing) is commonly undertaken in general practice, being one of a range of assessment and screening procedures, such as new patient registration, screening for diabetes mellitus and testing for infections and pregnancy.

Indications

The composition of urine can change dramatically as a result of disease processes. It may contain red blood cells, glucose, proteins, white blood cells or bile (Marieb and Hoehn 2010). It can reveal diseases that have gone unnoticed because they do not produce striking symptoms, and may also be used in ongoing management of conditions (Higgins 2008).

Screening: for systemic disease, for example, diabetes mellitus or renal conditions.

Diagnosis: to confirm or exclude suspected conditions, for example urinary tract infection.

Management and planning: to ascertain as a baseline, monitor progress of an existing condition and/or plan programme of care and medication (Wilson 2005).

Methods of urinalysis

Renal clearance refers to the volume of plasma that is cleared of a particular substance in a given time, usually 1 minute. Renal clearance tests are done to determine the glomerular filtration rate (GFR), which allows us to detect glomerular damage and follow the progress of renal disease (Marieb and Hoehn 2010).

In the microbiology laboratory, urine samples constitute about 40% of the total workload; of these, 70–80% of samples are not infected. This means that much time, energy and finances are wasted on unnecessary sample processing and investigation (Bayer Diagnostics 1997).

Further testing may be necessary, such as culture and sensitivity testing under laboratory conditions, to identify organisms responsible for infection and to determine the most effective treatment (Wilson 2005) (Table 12.6). Twentyfour hour collection is also used to measure substances such as steroids, white cells and electrolytes or to determine urine osmolarity (Tortora and Derrickson 2009).

Table 12.6 Routine observations of urine: possible indications and plan of action

Observation Colour Possible indications Plan of action

Green Pseudomonas infection, presence of bilirubin Culture and microscopy

Excretion of cytotoxic agents, for example mitomycin, or substances, for example methylene blue Discard with care

Pink/Red Blood Culture and microscopy. If currently receiving chemotherapy, for example ifosfamide, further mesna may need to be given

Excretion of cytotoxic agents, for example doxorubicin Discard with care

Orange Excess urobiliogen, rifampicin Discard

Yellow Bilirubin Discard

Brown Bilirubin Discard

Odour

Fishy Infection Culture and microscopy

Sweet smelling Ketones Culture and microscopy

Debris

Cloudy Infection, stale urine Culture and microscopy

Sediment Infection, contamination Culture and microscopy

Modifi ed from Rigby and Gray (2005) with kind permission from Nursing Times

Before using a reagent strip to analyse a sample of urine, the following observations should be made.

Colour.

Clarity.

Odour.

These properties should be considered with reference to clinical condition, urine output and fluid balance records over the past 24 hours.

The following factors can affect the analysis of results.

Bilirubin and urobilinogen are relatively unstable compounds when subjected to light and at room temperature, so it is important to use fresh urine to obtain the most accurate result.

Exposure of unpreserved urine at room temperature for a considerable period of time may result in an increase in microorganisms in the urine and change in pH.

Bacterial growth of contaminated organisms in urine may produce a positive blood reaction.

Urine that is high in alkaline may show falsepositive results in respect of presence of protein.

Glucose in urine may reduce its pH as a result of metabolism