How to prepare for your baseline blood test
Most people don't know how to prepare for a blood test, and small things in the days before can throw your numbers off. This guide walks you through everything you need to do so your results reflect your actual baseline.
The 72 hours before your blood draw determine whether your results reflect your actual baseline or might have some inaccuracies. Follow this protocol.
Sleep
Aim for 7 to 9 hours the night before. Avoid all-nighters or significantly disrupted sleep in the 48 hours prior. Sleep deprivation elevates cortisol, fasting glucose, and inflammation markers, so a rough night can make your results look off even if nothing else has changed.
Alcohol
Avoid alcohol for 48 to 72 hours before your test. Alcohol skews liver markers (ALT, AST, GGT), triglycerides, fasting glucose, and uric acid. Even one or two drinks the night before will register.
Training
Skip high-intensity training, heavy lifting, and long endurance sessions for 48 hours before your draw. Light walking is fine. Strenuous exercise elevates hs-CRP, liver enzymes, CK, and cortisol, making the numbers look worse than they are.
Fasting
Fast for 10 to 12 hours overnight. Water only: no food, coffee, tea, juice, gum, mints, or flavoured water. Going in the morning is easiest so you're not fasting through the day. Fasting is required for accurate fasting glucose, fasting insulin, HOMA-IR, and your lipid panel.
Hydration
Drink water normally the day before and the morning of your test. Don't dehydrate yourself trying to fast. Water is allowed and encouraged. Adequate hydration improves draw quality and prevents skewed haematocrit and sodium readings.
Supplements and medication
Continue all prescribed medications as normal unless your GP specifically advises otherwise. Pause biotin and B-complex supplements for 48 to 72 hours before, as biotin interferes with multiple immunoassays, including thyroid markers.
Pause non-essential supplements (fish oil, vitamins, adaptogens) for 24 to 48 hours. Make a note of your current medications and supplements so your results can be interpreted in context.
Don't change what's normal
This test captures where you actually are, not an idealised version of you. In the lead-up:
Don't change your diet in the week before
Don't start a new training program
Don't crash diet, carb load, or detox
A falsely flattering baseline gives you false reassurance and a misleading follow-up three months later.
The morning of your test
Collection centres are walk-in, so you can't book ahead. Centres get busy first thing in the morning, so arrive 10 to 15 minutes before opening to be near the front of the queue.
On the day:
Water only, no food or coffee
Take prescribed medications as usual
Bring your pathology request form (sent to your inbox)
Wear short sleeves or layers you can roll up
You can find your nearest collection centre and check opening hours here: https://app.bloodygoodtests.com.au/collection-centres
A note on medical advice
This article is for general health information only and is not medical advice. Continue prescribed medications unless your GP advises otherwise. If you have an existing medical condition, speak with your doctor before changing your routine.