Your lab order just landed in your inbox, and the first question that pops into your head is a simple one: can I eat breakfast? It's one of the most common questions we hear before a hormone blood test, and the honest answer is that it depends on what the panel measures and what your provider wants to see.
This guide walks through when fasting matters, how to time your draw, what to do about medications and supplements, and a simple checklist you can follow the night before. It's written around Summit Rejuvenation's standard 52-marker panel, but most of it applies to any hormone blood test.
The short answer: fasting is preferred, not required
At Summit, fasting before your hormone panel is preferred but optional. Here's why it's preferred: the panel doesn't only look at hormones. It also includes glucose and a lipid panel, and those markers read most accurately when you haven't eaten. A big breakfast can nudge your glucose and triglycerides up for a few hours, which makes those numbers harder to interpret.
Hormones like testosterone, estradiol and thyroid markers are less affected by a meal than glucose and lipids are. So if you forget and eat, it isn't a wasted trip. Tell the person drawing your blood and your care team, and they'll read your metabolic markers with that in mind.
If you choose to fast, keep it simple. Have dinner the night before, then stick to plain water until after your draw. Water is always fine, and it helps (more on that below). Save the coffee, cream and breakfast for afterward. If your provider gives you a specific instruction, follow theirs over anything here.
What's actually in the panel
It helps to know what's being measured, because that explains most of the prep rules. Summit's standard panel covers 52 markers in a single draw:
- Sex and pituitary hormones: total testosterone, estradiol, progesterone, DHEA-S, SHBG, LH, FSH and prolactin
- Thyroid: TSH plus the active thyroid hormones
- Blood count: a complete blood count, including hematocrit
- Metabolic and blood sugar: a comprehensive metabolic panel and A1c
- Lipids: cholesterol and triglycerides
- Iron studies and vitamins: iron, ferritin, B12, folate and vitamin D
- One more by sex: PSA for men, and a blood cortisol test for women
Insulin and IGF-1 can be added on request. You can see every marker on our bloodwork page, and our guide on how to read your hormone blood panel explains what each group tells us.
Timing your draw
Fasting gets the attention, but timing often matters just as much.
For men, draws are usually scheduled in the morning. Testosterone follows a daily rhythm and is generally highest early in the day, so a morning draw gives a reading that's easier to compare from one test to the next. Morning also makes fasting easy, since you're already coming off a night's sleep.
For women, the right timing depends on where you are in your cycle and which hormones your provider is looking at. Someone with regular periods, someone in perimenopause and someone past menopause may each be asked to come in at a different point. Your care team will tell you when to go rather than apply one rule to everyone.
If you're already on hormone therapy, timing around your dose matters a lot. The reading depends on when your last dose was, so your care team will tell you exactly when to draw based on your schedule. Write down the date and time of your last dose and bring it with you. That one detail makes your results far easier to read.
Medications and supplements
Keep taking your regular prescription medications unless your provider tells you otherwise. Don't stop anything on your own to "get a cleaner number."
Supplements are a different story, and one deserves special mention: biotin. It's in many hair, skin and nail products and in a lot of multivitamins, and it can interfere with several lab tests, including some hormone and thyroid assays. Tell us about every supplement you take, especially biotin, so your provider can tell you whether to pause it before your draw.
Also mention any recent illness, a hard workout the day before, or a bad night's sleep. None of these ruin a test, but they're useful context when your provider reads the results.
Hydration: the easy win
Drink water the evening before and the morning of your draw. Being well hydrated makes the draw easier, and dehydration can raise hematocrit, which can make that reading look higher than your real baseline. That matters for anyone thinking about or already on testosterone therapy, since hematocrit is one of the markers we watch closely.
Your night-before checklist
Here's the whole thing on one list:
- Check your instructions. If your provider gave you a fasting or timing instruction, that wins.
- Eat dinner, then water only if you're fasting.
- Note your last hormone dose (date and time), if you're on therapy.
- List your supplements, and ask about pausing biotin.
- Hydrate in the evening and again in the morning.
- Plan a morning draw if you're a man, or the timing your care team gave you if you're a woman.
- Bring a snack for right after.
Where to get your blood drawn
You can have your draw at one of our clinics in Chesterfield, South County, Wentzville, Cottleville or Jacksonville, or at a LabCorp location near you. If you go the LabCorp route, we send the lab order and you book the visit at the location and time that suit you. That works well for telehealth patients, since telehealth is available 24/7 in all 50 states.
What happens after the draw
Results usually come back within a week. Then you'll have a review of findings with a member of our licensed medical team, in the clinic or by phone. They go through what your results show, how they line up with how you actually feel, and what your options are. If hormone therapy makes sense for you, your protocol is built around your labs, your symptoms and your goals, not a template.
Once you're on a protocol, follow-up labs come at 8 to 12 weeks, then every 6 months unless your protocol changes. Those follow-ups use the same full panel, so the prep is the same every time. Active patients can message their care team between visits for fast replies, and provider consults come at no charge for active patients.
A quick note on other services: medical weight loss, including semaglutide and tirzepatide, needs no labs to start. It begins with a consult, and a provider may recommend labs for some patients. Peptide therapy needs no labs either. Bloodwork is part of hormone care, covered on our testosterone therapy and women's hormones pages.
On payment, Summit doesn't accept insurance, and HSA and FSA cards are accepted.
Here's your next step
If you've been putting off labs because you weren't sure how to prepare, now you know: water, timing, and a quick list of what you take. Start with a consult and we'll set up your lab order and tell you exactly when to go. What questions do you have? Ask us when you book.
For a deeper look at the markers themselves, see our HRT blood tests guide.
Frequently asked questions
Do I need to fast before a hormone blood test?
At Summit, fasting before the hormone panel is preferred but not required. The panel includes glucose and lipids, which read most accurately after a fast. If you do eat, tell your care team so they can read those markers with that in mind.
Can I drink coffee before my blood test?
If you're fasting, stick to plain water until after your draw. Coffee, especially with cream or sugar, can affect your metabolic markers. Water is always fine and helps keep you hydrated.
What time of day should I get my hormone labs drawn?
Men are usually scheduled in the morning because testosterone is generally highest early in the day. For women, timing depends on cycle status and which hormones are being checked, so your care team will tell you when to go.
Should I stop my supplements before a hormone blood test?
Tell your provider about every supplement you take, especially biotin, which can interfere with some hormone and thyroid tests. Your provider will tell you whether to pause anything. Keep taking prescription medications unless your provider says otherwise.
Do I need labs before medical weight loss or peptide therapy?
No. Medical weight loss, including semaglutide and tirzepatide, needs no labs to start; it begins with a consult, and a provider may recommend labs for some patients. Peptide therapy needs no labs.
How often will I need follow-up labs?
Once you're on a hormone protocol, follow-up labs come at 8 to 12 weeks, then every 6 months unless your protocol changes. Follow-ups use the same full panel, so you prepare the same way each time.