CoreVitals Special Instructions
for Test Timing
Blood Test Preparation Instructions
To get the most accurate and meaningful results from your blood test, please read the following instructions carefully before your appointment. This guide includes general preparation, time-of-day recommendations, and specific considerations for hormone, thyroid, metabolic, and nutrient-related tests. If you're tracking your menstrual cycle or testing reproductive hormones, please ensure you read the hormone-specific timing instructions.
When Should I Book My Test?
We recommend booking your blood draw between 8:00am and 10:00am, as this timing provides the most reliable results for many sensitive biomarkers such as hormones, cortisol, iron, and fasting glucose.
To get the most accurate and meaningful results from your blood test, please read the following instructions carefully before your appointment. This guide includes general preparation, time-of-day recommendations, and specific considerations for hormone, thyroid, metabolic, and nutrient-related tests. If you're tracking your menstrual cycle or testing reproductive hormones, please ensure you read the hormone-specific timing instructions.
Blood Test Preparation Instructions
To get the most accurate and meaningful results from your blood test, please read the following instructions carefully before your appointment. This guide includes general preparation, time-of-day recommendations, and specific considerations for hormone, thyroid, metabolic, and nutrient-related tests. If you're tracking your menstrual cycle or testing reproductive hormones, please ensure you read the hormone-specific timing instructions.
4 Days Before Your Test
- Stop all non-essential supplements (including vitamins, minerals, herbal remedies, protein powders, collagen, and nootropics).
- Continue all prescription medications unless your doctor has advised you to stop.
- If you are taking biotin (vitamin B7), stop it 48 hours before your test. It can interfere with certain hormone and thyroid results. If prescribed, speak with your doctor before pausing.
- If you're on hormonal contraception or HRT, be aware that it can affect your hormone test results. For a true baseline of natural hormonal function, you’d need to be off hormonal contraception for several months prior. Speak to your GP if you're considering this option.
1–2 Days Before Your Test
- Avoid alcohol and caffeine for 12–24 hours before your appointment.
- Avoid red meat and high-protein meals for 24 hours before testing.
- Avoid strenuous or vigorous exercise for 24–48 hours before testing.
- Avoid sexual activity, nipple stimulation, heavy meals, and stress for 24–48 hours beforehand.
Day of the Test
- Fast for 8–12 hours, unless otherwise instructed (water only). This is important for glucose, lipids, iron, insulin, and sometimes nutrient markers. Do not fast longer than 12 hours.
- Stay well hydrated – drink water in the morning unless advised to be dry fasting.
- Continue to avoid stress, exercise, food, and sexual activity that morning.
- If you're testing thyroid hormones:
- If taking levothyroxine, you may take it before or after the test.
- If taking liothyronine (T3) or desiccated thyroid extract, take it after the test.
- If taking levothyroxine, you may take it before or after the test.
- Avoid testing when acutely unwell, febrile, or under unusual stress unless the purpose is to investigate that state.
- Wear loose clothing to allow easy access to your arm.
Menstrual Cycle & Hormone Testing (For Women)
- For baseline reproductive hormones (e.g. FSH, LH, estradiol): test between day 2–5 of your menstrual cycle, ideally on day 3.
- For progesterone or ovulation assessment: test around day 21 of your cycle (or 5–7 days after ovulation), assuming a 28-day cycle. Also consider testing at this time for assessment of Oestrogen Dominance / Imbalances in the Oestrogen to Progesterone Ratio.
- If you are not having regular periods, hormone tests can be done at any time.
After the Test
- You may resume your usual diet, normal supplements and medications unless told otherwise.
- If you felt faint during the blood draw, rest and hydrate well post-appointment.