Preparation for the tests - "Antėja laboratorija"

Preparation for the tests

One of the most important factors determining the accuracy and reliability of laboratory tests is you. Proper preparation is essential, to ensure the quality of your test results! Below, please find information you need to know prior to your tests. 

Tips on how to prepare for the laboratory tests: 

  • If you are taking medications that could interfere with the test results, please tell us before submitting your blood for a blood test. 
  • You can have your blood tests done after a meal, unless your doctor recommends otherwise. 
  • Avoid intense physical activity (which can affect some enzyme activity and the concentrations of various substances in the body). 
  • Wait at least 12 hours after X-ray and ultrasound examinations, as well as reflexology and physiotherapy treatments. 
  • Serological testing for infectious diseases is recommended 2–4 weeks after a suspected infection, to obtain a sufficient antibody concentration production. 
  • When testing for infections, it is important to know the time of contact with a possible source of the infection. 
  • Inform the prescribing doctor of the day of your menstrual cycle. 
  • As the concentration of some substances in the blood or the activity of enzymes varies at different times of the day, we recommend having some tests conducted in the morning, such as tests for cortisol and testosterone. 

The definition of fasting (abstinence from food) refers to a state of not eating food or drinking liquids for a period of about 12 hours. Only non-carbonated (still) water should be drunk before blood is drawn for the laboratory tests. 

Tests that require fasting are conducted: 

  • When the TG after eating is >4.5 mmol/l. 
  • For known hypertriglyceridaemia. 
  • During recovery from hypertriglyceridaemic pancreatitis. 
  • When taking medications that can cause severe hypertriglyceridaemia. 
  • For some special tests, such as the glucose tolerance test. 

It is recommended to avoid drinking coffee and tea, or consuming chewing gum. Certain substances can interfere with the glucose test results. Caffeine increases your blood sugar levels. 
Prolonged fasting (>12 hours) before blood draws is not recommended, especially in patients with low body fat. This can lead to too low blood sugar levels, and even an increase in ketone bodies, as well as low iron and haemoglobin levels. 

  • When taking medicines and dietary supplements, patients should check with their doctor to learn whether to discontinue them or not. Before the blood test it’s recommended:  
Iron level test Do not use iron supplement for 1–2 days
Vitamin D  Do not take vitamin D supplements in therapeutic doses for 24 hours.
Thyroid function tests Do not take l-thyroxine or other thyroid medication on
the day before the blood test.
vitB12 Vitamin B12 Do not take the supplement for 2–3 days. If you had an IV drip
for supplements (B12 and B9) after IV drip please wait 1–2 weeks
before conducting a blood test for vitamins B9 and B12.
FA Folic acid (vitamin B9)  Do not take biotin supplements for at least 48 hours.
Active vitamin B12 Do not take the B12  supplement for 2–3 days. 
Do not take biotin supplements for at least 48 hours. 
.Vitamin C (ascorbic acid) Do not take the Vitamin C supplement for 2–3 days.
Vitamin H (biotin) Do not take the investigational vitamin supplement for 2–3 days.
Vitamin K (Phylloquinone) Do not take the investigational vitamin supplement for 2–3 days.
Vitamin B1 (thiamine) Do not take the investigational vitamin supplement for 2–3 days.

Interference of biotin with the laboratory test results 

As biotin interferes with many laboratory tests, the patient should discontinue the consumption of biotin (multivitamins or supplements containing biotin or "Vitamin B7") for 48 hours or more before the laboratory test, to minimise interference with the test. 

Biotin interferes with the following tests: 

Active vitamin B12 (AB12) Cytomegalovirus IgG antibodies (CMV) Free beta human chorionic gonadotropin (B-HCG) N-terminal B-type (brain) natriuretic pro-peptide (NT-proBNP) Thyroglobulin (Tg)
Cyclic citrullinated peptide 
antibodies (anti-CCP) 
Cytomegalovirus IgM antibodies (CMV) Free thyroxine (FT4) Pregnancy associated plasma protein-A (PAPP-A) Testosterone (TSTO)
Hepatitis B surface antigen antibodies (aHBs) Estradiol (E2) Hepatitis B core antigen antibodies (aHBcore) Parathyroid hormone (PTH) Combination HIV
Hepatitis C virus antibodies (aHCV) Folic acid (FOL) Hepatitis B surface antigen (HBsAg) SARS-CoV-2 IgG antibodies  
Adrenocorticotropic hormone (ACTH) Free prostate-specific antigen (fPSA) Homocysteine (HCY) Sex hormone binding globulin (SHBG)  

What should I do after the blood draw? 

  • The puncture site, after being sealed by the GP nurse, must be pressed and held by the patient for about 5 minutes or more (depending on the clotting rate). 
  • Tell the nurse if you feel unwell or weak. 
  • It is recommended to only remove the band aid from the puncture site after an hour. 
  • Do not do heavy work or be involved in active sports after the blood draw (otherwise, bruising may occur). 

GTT (glucose tolerance test) 

2-point glucose tolerance test (GTT) for pregnant women: 

  • Before the test, the pregnant woman should continue a normal diet for at least 3 days, without a restriction of carbohydrates.  
  • The test is carried out in the morning, and the pregnant woman must have fasted for 8-14 hours.  
  • We recommend conducting a test with the pregnant woman in a seated position; no smoking is allowed during the test. 

There are also certain requirements that need to be met before a glucose tolerance test:  

  • Do not fast for three days before the test, eat more than 150 g of carbohydrates per day and engage in normal levels of physical activity.  
  • Do not eat for 10–16 hours before the test, but you can drink water.  
  • Do not smoke for 15 minutes before and during the test.  
  • It is not recommended to conduct tests for women during menstruation.  
  • Some medications (glucocorticoids and oestrogens) and conditions (fever and prolonged bed rest) increase blood glucose levels, so a glucose tolerance test should be performed when these factors are absent. 

Tips on how to prepare for laboratory urine tests: 

If you plan to collect a urine sample for laboratory tests, we recommend using a disposable urine container. The urine is collected in a special disposable container, which is available at the pharmacy. The disposable urine container does not need to be washed or otherwise prepared. For babies and young children, a urine sample can be collected using urine collection bags. 

NOTE: Please note that for microbiological tests (urine culture), the container must be sterile and kept in a sealed container. 

NOTE: It is unacceptable to urinate in bottles, jars and other containers not intended for this purpose. Various substances such as sugar residues or bacteria can interfere with the test results. 

For a few days (at least 10-12 hours) before the collection of urine for testing, we recommend following a standard diet and eating as usual, but avoid spicy, salty foods and products that can change the colour of the urine (e.g. carrots, beetroot, etc.), and to drink a normal intake of liquids with no alcohol. Avoid heavy physical activity and prolonged standing for longer than usual before the urine collection. Excessive exercise can lead to protein and ketone bodies in the urine, or an increase in their levels. Orthostatic proteinuria often occurs as a result of prolonged standing. 

We recommend avoiding sexual intercourse for 24 hours before the urine sample collection. Urine testing after sexual intercourse can be complicated by the presence of semen in the urine. A high sperm count does not allow for a proper microscopic evaluation of the urine sediment. There may also be minor lesions in the urethra, which may result in the presence or an increase of epithelium and erythrocytes, or the detection of bacteria in the urine. 

Avoid having a urine test during menstrual bleeding and for 2-3 days before and after menstruation. If necessary, these circumstances should be documented. When collecting urine samples during menstruation, the urine is often contaminated with erythrocytes and epithelium, making it impossible to obtain reliable results. Your doctor may interpret this result as haematuria. 

Discontinuation of medicines is not necessary, but you should inform the laboratory and doctors of any medicines or food supplements you were taking at the time of the urine collection. Some of these substances may interfere with the results of urine tests: 

  • Vitamin C supplements 
  • Iron supplements 
  • Metronidazole 
  • Riboflavin 
  • Laxatives 
  • Methocarbamol 
  • Nitrofurantoin 
  • Some other medicines 

Before collecting urine for the microalbumin/creatinine test, we recommend not taking the following medicines for 8–12 hours: 

  • Acetaminophen (paracetamol) 
  • Metabolites of N-acetyl-p-benzoquinone imine (NAPQI) 
  • N-acetylcysteine (NAC) 
  • Metamizole (novaminsulfon and dipyrone) 
  • 4-aminoantipyrine (4-AAP) 
  • Metabolites of 4-methylamino-antipyrine (4-MAP) 

Before collecting the urine, it is necessary to find out the purpose and the method that is to be used: 

Purpose Procedure
Morning urine It should be collected after waking up, i.e. after a night's rest of 8 hours or, if this is not possible, at least 4 hours after the previous urination.
"Midstream portion" of the urine 
Neither the first nor the last portion of urine is collected; instead, the midstream portion sample is collected (20–50 ml).
"All day urine" The urine is collected all day. When you get up in the morning, pee in the toilet and record the time. 
Then, all the urine is collected for a period of 24 hours. The last urine must be collected the next day, at the same time as on the first day. 
STD urine test by PCR Do not urinate for 3-4 hours before the collection, and do not wash the external genitals. The first portion of the urine is collected (“first drops”).
Urine for a cytopathology test Collect the second portion of the day, 3-4 hours after the morning urination.

A urine test is a quick and easy way to assess your kidneys and other organs, and to test for heavy metal poisoning, sexually transmitted diseases and other health problems. Statistics show that as many as 30% of people have changes in their urine, but these figures can also be distorted by the improper preparation for urine tests. 

IMPORTANT: The urine for testing must be collected only in a disposable plastic container. Urine collected in other containers (jars, food containers, etc.) is not suitable for testing and will not be accepted. We do not recommend conducting a urine test with women during menstruation. 

IMPORTANT: Different methods are used for urine tests (general clinical tests, molecular diagnostics (PCR) and microbiological tests), and they require different preparations (such as the first urine stream or midstream urine portion)! Here is the information you need to know, in order to prepare properly for your urine testing. 

When you prepare for the collection of urine for testing, you must adhere to the following general rules: 

  • Wash your hands with soap and water (clinical, PCR and microbiological). 
  • Wash your external genitalia with water or wipe with a clean cloth moistened with water, without using any disinfectants (clinical and microbiological). 
  • Dry the external genitalia (clinical and microbiological). 
  • Do not touch the inside of the disposable plastic container (clinical, PCR and microbiological). 
  • After collecting the sample, put the lid of the container on tightly and dry the outside (clinical, PCR and microbiological). 
  • Write your name, year of birth and time of the sample collection (clinical, PCR and microbiological) on the container. 

You will need a disposable container for general and PCR tests, or a sterile container in a sealed package for microbiological tests. 

The first portion of the urine is needed to detect sexually transmitted pathogens. The urine is tested by the molecular diagnostic (PCR) method using morning urine, or the patient must not have urinated for at least 4 hours. 

Process of collecting the first portion of urine for men and women: 

  • The patient shall follow the general rules for the urine collection (see above). 
  • A urine sample shall be collected in the morning, within the first two hours of wakefulness. 
  • The first portion of urine shall be collected in an empty, clean plastic container – 10-30 ml of the first drops of urine. 
  • The urine sample can be stored at room temperature for up to 6 hours; if the sample cannot be delivered within 6 hours, the sample must be stored at a 2-8 °C temperature.

24-hour urine collection: 

  • The 24-hour urine collection procedure can be carried out best when you are at home all day. 
  • Store the urine collection container in a dark and cool place (protected from direct sunlight) for the next 24 hours. 
  • When you get up in the morning, pour the first portion of urine down the toilet. Collect the next portion of urine in a container. This will be the starting point for the 24-hour urine collection. 
  • After 24 hours from the start time, complete the urine collection process in the urine collection container(s). 
  • Mix the 24-hour urine collection content and dispense 50 ml into a separate sterile container, labelled with the patient's name, date, start and end of the urine collection (hours/minutes), and deliver this to the laboratory. 

Process of collecting the midstream portion of urine for men and women: 

  • The patient shall follow the general rules for urine collection (see below). 
  • The urine should only be collected in a sterile container in sealed package. 
  1. Wash your hands with soap and water, and dry them with a disposable paper towel. 
  2. Unclamp the foreskin / spread the labia apart. 
  3. Wash the tip of your penis with water or wipe with a clean damp paper towel / Wash the external genitalia with water or wipe with a clean damp sanitary napkin (clean with a downward motion). 
  4. Dry your genitals with a paper towel. 
  5. Pour the first portion of urine into the toilet. 
  6. Without interrupting the flow, collect 5-10 ml of the midstream portion of urine in a sterile container. Try not to touch the urine or the inside of the container. 
  7. Finish urinating into the toilet. 
  8. Write your name, year of birth and time of the sample collection on the container. 
  • If your bladder is empty, there is no need to drink any fluids. The micro-organisms in urine multiply very quickly, so we recommend bringing the urine container to the procedure room as soon as possible. If you are not able to do so, the urine should be stored in a refrigerator at a +4 °C temperature for up to 8 hours. 
  • The urine container must contain at least 3 ml of urine. 

For men 

For women 

Tips on how to prepare for coprological laboratory tests 

If you are planning to collect a stool sample for laboratory tests, we recommend using a plastic container. The stool shall be collected in a special disposable container, which is available at the pharmacy. You must also prepare a clean, dry container to collect the stool in. The coprological test is carried out without any special preparation on the part of the patient, who should be following a normal diet and not fasting or overeating. For people with constipation, stool collection can be a problem. To facilitate bowel movements, it is a good idea to increase the amount of fluid and fibre in your diet; for example, by including wholemeal cereals, bran, fruit and vegetables. 

  • The stool should be collected in a dry and clean special container. 
  • The stool is unsuitable for testing if the patient has used enemas, suppositories, sympathicotropics or laxatives, bismuth or barium preparations. 
  • The stool sample should be collected with a spatula from several places. The stool must be free of urine impurities. 
  • The amount of stool required for testing is 5-15 g. 
  • Your name and date of birth, and the time of collection (to the exact minute) must be written on the container. 
  • The container containing the sample must be placed immediately in a refrigerator and stored at a 2-8 °C temperature until its delivery to the laboratory. 
  • The stool sample must be delivered to the laboratory within 24 hours of its collection. 

In the case of testing for human pinworms, the sample shall be taken by a general practice nurse. 

Stool testing and medicines: 

  • Anti-constipation drugs (laxatives), such as lactulose, are mild medications used to treat constipation and theoretically should not interfere with the results of the test, so they can be used. 
  • The best time to conduct a stool parasite examination is before or after antibiotic treatment. 

If you are taking other medicines, check with your doctor before taking the stool test to make sure they will not interfere with the results. 

How to prepare for genital scraping: 

Recommendations for women before genital scraping: 

  • Do not use sanitary pads or intravaginal preparations, avoid sexual intercourse or washing the vagina for 24 hours before collection of the test material. 
  • Do not plan to collect the test material during menstruation. 

Recommendations for men: do not urinate for 2-3 hours before the collection of the genital scraping. 

How to prepare for a cervical cytology (PAP) test: 

For two days before the PAP, the following is recommended: 

  • Have no sexual intercourse and do not use lubricants for 48 hours before the test. 
  • Do not use sprays or powders near the vagina, tampons, vaginal medications, vaginal spermicidal foams, creams or gels for 48 hours. 
  • Do not wash the vagina with water, acetic acid solution or any other liquid before the PAP smear. 

Do not schedule a PAP smear during your menstrual cycle and for 4 days after. The best time to have a PAP test is at least 5 days after the end of your period, on Days 10-20 of your menstruation cycle. 

In all cases, the test material (samples/ specimens) delivered to the laboratory shall be evaluated against the established criteria for its suitability for testing. If it does not meet the requirements, no tests shall be carried out. The reason shall be indicated in the order – MAC (Material Rejection Criterion). You will be informed of the established MAC, in accordance with the contractual procedure or in the test report. 

Criteria for assessing the suitability of the test material 

  1. Completion of documentary information about the patient (whether the referral note contains sufficient data for recording, performing and interpreting and presenting the results). 
  2. Identification of the test material being sent (whether the test material has been correctly labelled). 
  3. Suitability of the test material: 
    - Whether the correct material has been sent for the desired tests  
    - Whether it was collected at the right time 
    - Whether it is in the right container  
    - Whether the shelf life of the container is suitable 
    - Whether the quantity of the sample is sufficient 
    - Whether the ratio with the additives has been maintained in the container 
    - Whether it contains some changes or impurities visible to the eye (clots, haemolysis, etc.) 
  4. Whether the test material has been properly prepared for transport and delivered in accordance with the requirements (temperature, protection from light, etc., where applicable). 
  5. Whether the container and the test material were damaged during transportation. 
  6. Whether the stability of the test material is adequate for performing the desired tests.