Most blood tests need little preparation, but some need fasting or a set time of day. Here's how to get ready so your results are as useful as possible.
Most blood tests need very little preparation. Drink some water, bring your referral and turn up. Some tests, though, need you to fast or to have your blood taken at a particular time of day, and getting that wrong can make your results harder to interpret. The instructions on your pathology referral, and from your doctor, always come first.
Check your referral first
Your pathology referral lists which tests your doctor has requested, and it often includes preparation notes such as "fasting" or "morning collection". Read it as soon as you get it, not on the morning of the test.
If anything is unclear, ask. Your doctor or the collection centre can tell you exactly what's needed. It's much easier to sort out a question the day before than to discover at the counter that you should have skipped breakfast.
When and how to fast
Some tests, such as fasting glucose and certain cholesterol and lipid panels, are more accurate when you haven't eaten. Fasting usually means nothing to eat or drink except plain water for a set period beforehand, often overnight. Your doctor or referral will tell you how long.
A few practical tips.
- Book an early appointment so most of your fast happens while you sleep.
- Drink plain water. It keeps you hydrated and makes the blood draw easier.
- Skip tea, coffee, juice and chewing gum, even without sugar, unless you're told otherwise.
- Avoid alcohol the day before, as it can affect several results.
- Bring something to eat afterwards, especially if you tend to feel light-headed when hungry.
If you have diabetes or another condition where fasting could be a problem, talk to your doctor before you fast. They may adjust the instructions for you.
Timing matters for some tests
Some markers in your blood naturally rise and fall through the day. For those tests, your doctor may ask for a morning collection so your result can be compared fairly against reference ranges and against future tests.
If you're having a repeat test to see how something has changed, try to keep the conditions similar to last time, with a similar time of day and fasting state. That makes it easier for your doctor to tell a real change from normal day-to-day variation.
Medications and other things you take
Keep taking your usual medications unless your doctor tells you otherwise. Stopping something without advice can be risky.
Do tell your doctor about everything you take, including anything you've bought over the counter. Some products can affect certain test results, and your doctor can let you know if anything needs to be timed differently. When you complete a health questionnaire or speak with a doctor, this is exactly the kind of detail worth including.
The day before and on the day
What you do in the 24 hours beforehand can nudge some results. Hard exercise can temporarily affect certain markers, so it's sensible to keep the day before fairly quiet unless your doctor says it doesn't matter. Try to sleep normally and avoid unusual changes to your eating.
On the day, wear a top with sleeves that roll up easily. Bring your referral, your Medicare card if relevant and some form of ID. If you've fainted during blood tests before, tell the collector so they can have you lie down. Most collections take only a few minutes.
If you're nervous about needles, you're far from alone. Let the collector know, look away if it helps, and take slow breaths. Being well hydrated and having eaten (if you don't need to fast) can make the whole thing easier. Many collection centres don't need an appointment, but checking opening hours and wait times beforehand can save you a long sit in the waiting room.
After the test
You might have a small bruise where the needle went in. Keeping pressure on the spot for a few minutes afterwards helps. Eat something if you've been fasting, and get on with your day.
Your results go to the doctor who requested them. When they come back, it helps to understand what you're looking at, so read understanding your blood test results before your follow-up conversation. If you're getting tests because you're always worn out, blood tests for fatigue explains what doctors commonly check.
When to talk to a doctor
Contact your doctor before the test if you're unsure whether to fast, have diabetes, take medications that need careful timing, or are pregnant. After the test, seek advice if bruising spreads, the area becomes hot or swollen, or the bleeding doesn't stop with pressure. If you have chest pain, trouble breathing or feel faint, call 000.
Getting bloodwork through UHD BioHealth
At UHD BioHealth, an AHPRA-registered doctor reviews your detailed online questionnaire and makes contact within 24 hours. Where bloodwork is useful, they'll give you a pathology referral for a local collection centre, then go through your results as part of a written personalised plan with every cost itemised, which you read before paying anything. To begin, start your assessment.
Common questions
Can I drink water before a fasting blood test?
Yes, plain water is generally fine and usually encouraged, because being well hydrated makes it easier to draw blood. Avoid anything else, including tea, coffee, juice and chewing gum, unless your doctor says otherwise.
Should I take my usual medications before a blood test?
Usually yes, but check with your doctor. Some tests are affected by the timing of certain medications, so your doctor may give you specific instructions. Don't stop or change anything on your own.
How long do blood test results take?
Many common results are ready within a day or two, while some specialised tests take longer. The results go to the doctor who requested them, who will go through them with you.
Want a proper look?
An in-depth health questionnaire covering your history, symptoms, medications and lifestyle, read by an AHPRA-registered doctor within 24 hours. Bloodwork where it's needed, and a written plan before you pay anything.
General health information only, not medical advice. Complete our questionnaire and a doctor will assess whether a consult is right for you. Individual needs and outcomes vary. In an emergency, call 000.
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