Urinalysis study guide

Learning_Objectives

To understand the indications for performing urinalysis

To perform urinalysis without contamination

Understand how to instruct a patient on obtaining a mid-stream sample

To be able to accurately record findings

Theory_and_background

Theory and Background

Indications for performing urinalysis

It can be used as:

A screening test
To aid detection of abnormalities and aid diagnosis.
For monitoring and management of the patient’s condition.

Urinalysis may be routine as part of health check, well woman / well man clinic OR because it is indicated by patient history and presentation.

There are a large range of sticks available, some are very specific eg. testing for glycosuria (the excretion of glucose into the urine). Many have multiple tests on each strip please check the test strips selected have the specific tests on that you require.

What can you test for?

Glucose is not normally present in the urine. Presence may be due to elevated blood glucose levels or reduced renal threshold.

Protein (Albumin) albumin and globulin is normally in too low a concentration to give a positive reaction. False positive results occur in strongly alkaline urine. Abnormal proteinuria (the presence of an excess of serum proteins in the urine) is usually due to glomerular disease, which may be caused by a variety of conditions, including diabetes mellitus and hypertension.

Blood suggests urological disease and/or urinary tract infection (UTI). Results may be false positive if the container is contaminated with menstruation, bleach, perianal skin, stale urine or povidone iodine.

pH Value is usually slightly acidic within pH 5-6 (range 4.8 to 8.5). Lowest after overnight fast, highest after meals. Can be helpful when screening for renal disease, respiratory disease, certain metabolic disorders and specific therapeutic regimens, such as, sodium bicarbonate.

Nitrites are not normally present; produced by gram negative bacteria converting nitrates to nitrites. Ideally specimen should be obtained about 4 hours after last passing urine (voiding). Indicates a UTI and if the patient is symptomatic should be sent for further testing.

Ketones are abnormal urinary constituents, being breakdown products of fatty acid metabolism.

Bilirubin indicates hepatic or biliary disease.

Urobilinogen is normally present in urine, elevated levels may indicate liver abnormalities or excessive destruction of red blood cells. Urobilinogen tests should be considered with the bilirubin result to provide a differential diagnosis. A false negative result may be obtained from a stale sample.

Leucocytes – A positive result suggests pyuria (pus in the urine) associated with a UTI. Isolated results may not be significant. Repeated positives should not be ignored – but be aware of possible sources of contamination or other factors which may limit sensitivity to this test.

Specific Gravity (SG) sometimes called ‘density’. It is a laboratory test that measures the concentration of all chemical particles in the urine. Normal ranges given do vary between 1.001 -1.035 – so do check your product instructions carefully. Increased SG is seen in conditions causing dehydration, glycosuria, renal or heart failure or inappropriate antidiuretic hormone secretion or proteinuria. Decreased SG may be seen in excessive fluid intake or renal failure or pyelonephritis.

Tests can be falsely positive or falsely negative so remember to be aware of other factors…

Consider whether –

The sample could have been contaminated?

The patient’s medication could have affected the results or the sensitivity of the test?

The patient’s condition could have affected the results or sensitivity of the test?

Urine_collection

There are different methods and ways of collecting urine, some are listed below;

Routine sample of urine

MSSU – mid stream sample of urine

First Pass Urine– first few drops of urine, eg; in Chlamydia screening

CSU – catheter specimen of urine

EMU – early morning urine

24 hour urine

Some methods of collection;

Catheterised patients– (using needle free collection port)

Images above supplied and permission granted by B. Braun Medical Ltd

There are also many further types of devices that can be fitted to urine bottles to aid collection or urine can be collected in a sterile pot before transfer to a specimen bottle

The collection process

MSU is the recommended routine collection method.

Periurethral cleaning is only recommended if the sample is to go for analysis (water is considered sufficient). The first part of voided urine is discarded and, without interrupting the flow, approximately 10mL is collected into a CE marked leak proof container, or a sterile pot and transferred to a sample bottle. The remaining urine is discarded. (Standards unit, PHE June 2017, pg 24)

National guidance on this is below;

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/618126/B_41i8.2.pdf

Urine dipstick analysis

Before using CHECK

‘Appropriate’ for purpose – what do you want to look for? There are many differing types of analysis sticks that have differing tasks.
That the container has not been left open and that the sticks are in date.
That you are clear about the timings required for each test – and know how to read the strip accurately. You must be familiar with the sticks you are using.
That you have access to a clock/ watch that can count off seconds required.

Patient safety

Procedure

Check container

Consider –

Tests required?

How to read the strip?

Urine dipstick analysis

You must put on a pair of gloves and a plastic apron prior to opening the sample container and wash your hands when you finish.

Take a moment to consider the colour and turbidity (cloudiness of the urine) as these may be significant – and be linked to pathology or dietary and drug causes.

Remove strip & close container

Open the test strip container and remove a strip.

Replace the top immediately

Exposed strips absorb atmospheric moisture and renders the test zones inaccurate.

Do not contaminate the strips by placing them on a table, use a clean surface or clean blue roll.

Placing the dip stick in the urine sample

Briefly (no longer than one second) dip the test strip into the urine to wet all the test zones.

Compare analysis stick against colour scale

Place the strip on a piece of clean blue roll.

Compare test zones with the colour scale on the side of the strip container at the time indicated by the manufacturer.

The colours are stable for at least another minute allowing plenty of time for reading. NOTE your results.

Documenting_results

Documenting results

There are different methods for documenting the results, for example;

After dipping the urine compare the strip with the scale and remember the results OR
Record the details on a separate sheet to transfer to the notes OR
Prepare your documentation sheet with as much information as possible, prior to dipping the strip. After dipping it, remove the glove from your dominant hand and document the results.

Legal Considerations

All medical notes are written in BLACK pen (as are all legal documents) if not recorded electronically.

All the following points should be documented:

Patient’s name (in the correct place at the top of the history sheet (surname in capitals)).
Patient identifiers – their NHS Number (or hospital number, if they are in hospital and their NHS number is not available), and date of birth should also be written. Note there may no specific place for the DOB, so if this is the case, it should be clearly labelled.
The date and time are always noted on the patient’s notes at the start of the documentation.
Where the patient is when they are seen (e.g. ward 32 or A&E or GP surgery)
Responsible doctor (e.g. if in hospital, this would be the consultant the patient has been admitted under and what speciality they are)
The person documenting the result should sign next to or underneath (depending on the history sheet you are using) the last entry they’ve written, ensuring there are no significant gaps. The clinician’s name should then be printed legibly and their denomination clearly indicated (e.g. 1^st year medical student). Your signature means you are signing to say that everything from the start of your entry to your signature, is accurate.
Please note any errors should be crossed through once and initialled. They should be dated and timed, eg;-

DO…

Check expiry date on container before use
Replace cap & Store strips in a cool, dry place
Read instruction on pack insert
Time accurately for each test on the strip
Dispose of ALL waste appropriately AND WASH YOUR HANDS AGAIN
Document in full in black pen – including negative findings
Report abnormal results

IF it isn’t recorded IT wasn’t DONE

Don’t …

DO NOT Transfer strips to another pack
DO NOT Prolong dipping of test strip (1 second is enough)
DO NOT Hold the stick vertically after dipping
DO NOT Touch the test zone with fingers
DO NOT Contaminate your pen or the patient notes with urine.

References_and_other_useful_resources

Glossary