Patient preparation
Inform patients about fasting, diet, medication or test-specific instructions before collection.
Before sample analysis
Reliable results start before the sample reaches the laboratory
Pre-analytical factors can significantly influence laboratory results. Patient preparation, collection time, fasting status, physical activity, medication, diet, sample material, labelling, storage and transport conditions all play an important role in sample quality and result interpretation.
This page provides practical guidance for healthcare professionals to help ensure that samples are collected under the right conditions and that relevant pre-analytical information is documented correctly.
Key considerations
What to check before sample collection
Collection time
Collect samples in the morning where required and document the collection time when relevant.
Fasting status
Some tests require fasting for 8 to 12 hours. Water is usually permitted unless otherwise specified.
Physical activity and stress
Stress and intense exercise can affect hormones, muscle parameters, blood count values and urine results.
Sample material and containers
Use the correct tube, container or collection kit to avoid delays or repeat collection.
Documentation
Record relevant details such as fasting status, collection time, medication, urine collection period or deviations from instructions.
Patient preparation and collection conditions
Proper pre-analytical practices are essential to ensure accurate and reliable laboratory results. The following points highlight key factors to consider before sample analysis.
Some blood tests and urine collections require fasting for 8 to 12 hours. Patients should avoid food and drinks containing sugar or fat. Water is usually allowed unless otherwise specified.
Blood samples should preferably be collected in the morning, ideally between 7:00 and 9:00 a.m. Many reference values are based on morning fasting samples. If collection takes place later, document the time.
Patients should avoid stress and intense physical activity shortly before collection. These factors may affect stress hormones, creatine kinase, other muscle-related values, blood count parameters and some urine values.
Certain procedures should usually take place after blood collection, as they may affect results. This includes breast or prostate palpation, exercise ECGs, punctures and similar procedures.
For repeated tests, collect samples under comparable conditions whenever possible: same time of day, similar preparation and, where relevant, same body position.
Specific tests
Some analyses require additional preparation
Certain analyses require patients to avoid specific foods, drinks, nicotine, alcohol, supplements or medication before collection.
Examples include:
vanillylmandelic acid, adrenaline or noradrenaline: coffee, tea, alcohol and nicotine may need to be avoided;
oxalic acid in urine: vitamin C should not be taken during the 24 hours before collection;
hydroxyindoleacetic acid in urine: bananas, avocados, aubergines, pineapple, tomatoes and nuts should be avoided for two days before collection.
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