Information
Sample Collection Guide
Preparation shapes precision. This guide explains exactly how to prepare for every sample type we handle at Hilmi Lab — so that your results reflect your health, and nothing else.
Please note: this guide provides general preparation advice. Individual tests may carry specific requirements relating to fasting, medication, timing or cycle day. Always follow the instructions issued with your booking by Hilmi Lab, or those given by your treating doctor, and contact us if anything is unclear.
The principle
Why proper sample collection matters
A laboratory result is only as reliable as the sample it came from. Preparation is the part of the process that belongs to you — and it carries more weight than most patients expect.
Most errors happen before analysis
The majority of unreliable laboratory results originate at the pre-analytical stage — how, when and in what condition a sample was collected — rather than in the laboratory itself.
Biology changes through the day
Hormones, glucose, iron and many other markers follow daily rhythms. Sampling at the recommended time keeps your result comparable with reference ranges.
Food and medicines interfere
A recent meal, supplements or certain medications can alter measured values, occasionally enough to suggest a problem that does not exist.
Accuracy protects your care
A correctly collected sample means fewer repeat appointments, faster answers and clinical decisions you and your doctor can rely on.
Checklist
General preparation before any test
Eight steps that apply to almost every appointment at Hilmi Lab.
- 01Attend in the morning where possible — most blood tests are best taken between 07:00 and 11:00.
- 02Fast for 8 to 12 hours before fasting tests; still water is permitted and encouraged.
- 03Rest physically and mentally the evening before, and sit quietly for at least 30 minutes before your draw.
- 04Avoid alcohol for 24 hours and avoid strenuous exercise the day before.
- 05Take your samples before starting any new medication or supplement, unless your doctor advises otherwise.
- 06Bring a list of all current medicines, supplements and recent antibiotics.
- 07Bring photographic identification and your Hilmi Lab requisition or booking reference.
- 08Tell our team if you feel unwell, are pregnant, or have previously fainted during a blood test.
Blood samples
Blood sample collection
Morning, rested and fasting — the three conditions under which most blood reference ranges were established.
Timing
Attend between 07:00 and 11:00. Some hormone tests — cortisol, progesterone, prolactin and others — must be taken on a specific day or at a precise hour as directed by your doctor.
Fasting
Fast for a minimum of 8 hours and no more than 12. Still water is allowed; avoid tea, coffee, juice, chewing gum and smoking.
Hydration
Drink water normally before attending. Good hydration makes the draw easier and more comfortable.
Rest
Avoid physical exertion and emotional stress the night before, and rest for 30 minutes on arrival before the sample is taken.
Medication
Ask your treating doctor whether any medicine should be paused. Never stop prescribed treatment on your own, and always declare what you take at the point of collection.
After the draw
Keep gentle pressure on the site for a few minutes, avoid heavy lifting with that arm for an hour, and eat and drink normally afterwards.
Exceptions
- In urgent or acute situations — for example a full blood count or C-reactive protein — samples may be taken without fasting or outside the recommended hours.
- Where fasting is not possible, aim to attend 2 to 3 hours after your last meal to limit interference from post-meal lipaemia, and tell us the time you last ate.
- Glucose tolerance tests, therapeutic drug monitoring and certain hormone profiles follow their own strict timing protocols issued with your booking.
Urine samples
Urine sample collection
Technique determines accuracy more than any other factor in urinalysis.
Spontaneous (single) sample
- 01Collect the first urine passed in the morning wherever possible.
- 02Wash your hands and the genital area thoroughly with soap and water; do not use antiseptic products.
- 03Use only the sterile single-use container supplied by Hilmi Lab or bought from a pharmacy.
- 04Pass the first part of the stream into the toilet, then collect roughly 20 mL of the midstream directly into the container.
- 05Close the lid firmly without touching the inside of the container or lid.
- 06Deliver the sample to the laboratory within one hour; if that is not possible, refrigerate at 2–8 °C.
Important
- Do not collect urine during menstruation.
- For a urine culture, collect before starting antibiotics, or at least 7 to 10 days after finishing a course.
- If you are taking diuretics, or have symptoms such as frequent urination, pain on passing urine or lower abdominal discomfort, please tell our team so the sample can be interpreted correctly.
24-hour urine collection
Used for tests such as protein, glucose, calcium, metanephrines and normetanephrines.
- 01Note the exact time you begin the collection.
- 02Discard the first urine of the morning — the collection starts from that moment.
- 03Collect every subsequent urine, including overnight, into one clean 2–3 litre container.
- 04Keep the container refrigerated throughout the whole 24-hour period.
- 05Pass the final sample at the same time the following morning and add it to the container.
- 06Measure the total volume, mix the contents well, then transfer 40–50 mL into a clean, sealed container labelled with the total 24-hour volume.
Important
- For metanephrines, normetanephrines or urinary catecholamines, avoid caffeine for 72 hours beforehand and avoid smoking, physical exertion and stress during the collection.
- Where your doctor agrees, pause medicines known to interfere — monoamine oxidase inhibitors, tricyclic antidepressants, phenoxybenzamine, buspirone, L-dopa and beta-blockers such as labetalol and sotalol.
Infants and young children
- Clean the genital area gently and dry it before applying the bag.
- Fix the sterile paediatric collection bag around the genito-urinary opening: for boys the penis should sit inside the bag; for girls the vulva should sit within the opening so the upper genital area is covered.
- Once urine is passed, seal the bag, place it inside a sterile urine container to prevent leakage, and bring it to the laboratory promptly.
Stool samples
Stool sample collection
Simple to collect at home, provided the sample stays clean and reaches us promptly.
Stool culture (coproculture)
Collect before starting antibiotics, or at least 7 to 10 days after finishing them. Use the sterile container with the integrated spoon and take material from several areas of the stool, particularly any mucus, blood or watery portions.
General stool analysis
Collect a sample about the size of a hazelnut, or 5–10 mL if liquid, into the clean container provided. Do not overfill and do not use household containers.
Avoiding contamination
Pass stool into a clean, dry receptacle or clean paper first. The sample must not be mixed with urine, water from the toilet bowl, or cleaning products.
Timing and storage
Bring the sample to the laboratory within 1 to 2 hours. If a delay is unavoidable, refrigerate at 2–8 °C and deliver within 24 hours, or as directed for your specific test.
Faecal occult blood
Do not collect during menstruation, active haemorrhoidal bleeding or bleeding gums. Follow any dietary or medication advice supplied with your kit.
Parasitology
Three samples on separate days are often required. Avoid antacids, laxatives, barium contrast and antiparasitic medicines beforehand unless instructed otherwise.
Swabs and secretions
Throat, nasal and genital swabs
All swabs should be taken before antibiotics begin, or 7 to 10 days after a course has finished.
Throat swab
Attend in the morning before eating, drinking, brushing your teeth or using mouthwash, throat sprays, lozenges or local antiseptics. Collection should be before antibiotics, or 7 to 10 days after completing them.
Nasal swab
Do not use nasal sprays, drops, ointments or antiseptics beforehand. Avoid washing the nasal passages on the morning of your appointment.
Vaginal, cervical and urethral swabs
Attend outside menstruation, ideally in the first half of the cycle. Avoid intercourse, vaginal creams, pessaries, lubricants and intimate douching for 48 to 72 hours beforehand, and do not pass urine for at least one hour before a urethral swab.
Semen, saliva and buccal
Semen, saliva and buccal swab collection
Two sample types where abstinence, timing and temperature are decisive.
Semen analysis
- 01Observe sexual abstinence for a minimum of 2 days and a maximum of 7 days before the test.
- 02Pass urine and wash your hands and genital area with soap and water, then dry thoroughly before collection.
- 03Collect the entire ejaculate by masturbation, directly into the sterile container provided. Do not use condoms, lubricants or interrupted intercourse.
- 04Record the exact time of collection and note whether any part of the sample was lost.
- 05Keep the container at body temperature — close to the body, never refrigerated — and deliver it to the laboratory within 30 to 60 minutes.
- 06Postpone the test if you have had a fever, acute illness or a course of antibiotics in the previous 2 to 3 months, and tell us if so.
Saliva and buccal swab
- 01Do not eat, drink, smoke, chew gum or brush your teeth for at least 30 minutes — ideally 1 hour — before collection.
- 02Rinse your mouth with plain water and wait 10 minutes before you begin.
- 03For saliva tubes, allow saliva to pool naturally and fill to the marked line; avoid coughing up mucus.
- 04For a buccal swab, rub the swab firmly against the inside of the cheek for 30 seconds on each side, rotating as you go.
- 05Air-dry swabs as instructed and return them in the sleeve provided, without touching the swab head.
- 06Salivary hormone tests such as cortisol must be taken at the exact times printed on your kit.
Specialist testing
Genetic and microbiome sample collection
Advanced testing with, in most cases, remarkably simple preparation.
A single sample, once in a lifetime
Your DNA does not change, so most genetic tests need only one blood sample or buccal swab — no fasting and no timing restrictions.
Blood or buccal collection
Blood is drawn into a dedicated EDTA tube. Where a swab is used, follow the buccal instructions above and avoid eating or drinking for an hour beforehand.
Recent transfusion or transplant
Tell us if you have received a blood transfusion in the last 3 months or a bone marrow transplant at any time, as this can affect DNA analysis.
Prenatal testing (NIPT)
A standard maternal blood sample is taken from 10 weeks of pregnancy. No fasting is required, but the gestational age and number of foetuses must be confirmed.
Consent and counselling
Genetic testing requires informed consent, and results are always released alongside professional interpretation.
Gut microbiome sampling
- No fasting, dietary restriction or specific timing is required.
- Where possible, avoid collecting during or within 2 to 4 weeks of a course of antibiotics, and discuss probiotic use with your clinician.
- Do not collect during an episode of diarrhoea caused by acute infection, or while using laxatives or rectal preparations.
- Use only the collection kit supplied, following the illustrated instructions inside; the sample must not contact urine or toilet water.
- Seal the tube, complete the online questionnaire via the QR code in your kit, and return the sample to the centre that issued it.
Special requirements
Fasting, medication, hydration and timing
The four variables that most often change a result — and how to manage each of them.
Fasting
8 to 12 hours for glucose, lipid profile, insulin and iron studies. Longer fasting is not better and can distort results. Still water is always permitted.
Medication
Never stop prescribed treatment without medical advice. For drug level monitoring, samples are usually taken immediately before the next dose.
Hydration
Drink water normally. Dehydration concentrates the blood, makes venepuncture harder and can raise several measured values.
Timing and rhythm
Cortisol is taken between 07:00 and 09:00; iron and testosterone in the morning; female hormones on specific cycle days as advised by your doctor.
Supplements
Biotin can interfere with several immunoassays — stop high-dose biotin 48 to 72 hours beforehand where your doctor agrees. Pause vitamin and mineral supplements for 24 hours unless told otherwise.
Antibiotics
For any microbiological culture, collect before antibiotics begin or 7 to 10 days after the course ends, otherwise growth may be suppressed.
Storage and transport
Keeping your sample stable
Between collection and analysis, temperature and time are the two things that matter most.
Room temperature
Semen samples must be kept close to body temperature and delivered within 30 to 60 minutes. Never refrigerate them.
Refrigerated 2–8 °C
Urine, 24-hour urine collections and most stool samples should be refrigerated if they cannot reach the laboratory within one hour.
Getting it to us
Transport samples upright in a sealed bag, protected from direct sunlight and heat. Home collection samples are couriered under temperature-monitored conditions by our team.
Labelling
Every container must carry your full name, date of birth and the date and time of collection. Unlabelled samples cannot be accepted.
Please avoid
Common mistakes to avoid
Each of these is a frequent reason a sample must be repeated.
- Fasting for longer than 12 hours, or drinking coffee, tea or juice during the fast.
- Collecting the first part of the urine stream instead of the midstream.
- Using a non-sterile jar or a reused household container.
- Allowing urine, water or toilet paper to contaminate a stool sample.
- Starting antibiotics before a culture is collected.
- Refrigerating a semen sample or delaying its delivery beyond one hour.
- Attending for hormone tests on the wrong day of the menstrual cycle.
- Exercising intensely or drinking alcohol the day before testing.
- Forgetting to declare medication, supplements or recent illness.
- Leaving a container unlabelled, or unsealed during transport.
FAQ
Frequently asked questions
May I drink water while fasting?
Yes. Still water is permitted and encouraged, as good hydration makes the blood draw easier. Avoid tea, coffee, juice, milk, sweets and chewing gum.
Should I stop my medication before a blood test?
Never stop prescribed medication on your own. Ask your treating doctor whether a temporary pause is appropriate, and always tell our team what you are taking when the sample is collected.
Can I have tests taken while menstruating?
Blood tests are unaffected. Urine samples, stool samples for occult blood and vaginal swabs should be postponed until bleeding has stopped.
What if I cannot fast?
Tell us. Many tests can be taken 2 to 3 hours after a light meal, and we will record the time of your last meal so results are interpreted correctly.
How soon must my sample reach the laboratory?
Urine and stool within one hour, or refrigerated if delayed; semen within 30 to 60 minutes at body temperature. Blood taken at a Hilmi Lab centre is processed immediately.
Can samples be collected at home?
Yes. Our home collection service brings a trained phlebotomist to you, with barcoded samples and temperature-monitored transport to the laboratory the same day.
Do children follow the same preparation?
The principles are the same, with age-appropriate adjustments. Infants use sterile collection bags for urine, and fasting requirements are shortened — please ask our team for guidance.
What should I bring to my appointment?
Photographic identification, your booking reference or requisition, a list of current medicines and supplements, and any previous results relevant to the test.
Medical disclaimer: this page is provided for general information and does not constitute medical advice. Certain tests carry preparation requirements beyond those described here. Please always follow the instructions supplied by Hilmi Lab with your booking, or the advice of your treating healthcare professional, and seek urgent medical care for acute symptoms.
Contact Hilmi Lab
Unsure how to prepare? We will guide you.
Our team can confirm fasting requirements, timing and collection kits for any test before you attend — at any Hilmi Lab centre, or at your home.