This article outlines the most accurate times of the menstrual cycle to conduct blood tests, depending on what hormones are being tested.

This article relates to blood testing specifically as this is typically a method of testing that can be done with a referral from a General Practitioner. Commonly I use saliva or urine testing to assess hormonal status in clinic, as there are certain hormones or metabolites that are more accurately tested using these mediums.

Before outlining the best times to test certain hormones, it’s key to understand that the liver and gut play a role in breaking down hormones. If either of these pathways are not functioning optimally they commonly cause hormonal imbalances.

Overview of menstrual cycle

• Day 1 — this is the first day you see bright red blood.
• Day 14 — this is typically known as the day of ovulation, however only 10% of women actually ovulate on day 14. I recommend cycle tracking to find out what day you ovulate.
• Day 28 — not every woman has a 28-day cycle. A cycle ranging from 26 days – 35 days is considered normal.

Please note: If you are currently taking the oral contraceptive pill you don’t ovulate or have a period. Instead you have a withdrawal bleed.

What day of your cycle should you test your hormones?

I strongly advocate for testing with all my clients. The more data and information available the easier it is to address the root cause of the issue.

Hormone levels change across the month, understanding the flow of hormones and what day/s to test is key to help you understand if something is outside the normal range.

What day should FSH, LH and oestrogen be tested?

Day 3 of your cycle is the best day to test oestradiol (E2), follicle stimulating hormone (FSH) and luteinizing hormone (LH). Testing FSH and LH gives and idea of how well the brain is communicating with the ovaries. In women with PCOS LH to FSH ratio is often higher, at 2:1 or 3:1. 

Note: the LH to FSH ratio alone is not appropriate as the basis of a PCOS diagnosis but forms part of the overall picture.

Should oestrogen be tested on other days?

In my clinic I frequently test oestrogen levels between days 19-22 or 7 days after ovulation. Around this time of the cycle, testing provides an understanding of your progesterone to oestrogen ratio.

If your oestrogen is much higher than progesterone it’s possibly contributing to weight gain, mood changes and heavy periods.

What day should you test progesterone?

Progesterone levels are supposed to be highest 5-7 days after ovulation, approximately days 19-22. Many women don’t have text book 28 day cycles and so if you are looking at doing further testing I highly recommend tracking your cycle using the basal body temperature method, so that you can find out what day you ovulate.

What about testosterone?

Testosterone is highest in the morning and best tested between 7 am and 10 am. All women make testosterone. When levels are too high typically it’s linked to PCOS and symptoms like acne, irregular periods and hair growth around the face coupled with hair loss from the head. When levels are too low we see low libido, fatigue and poor muscle tone.

When it comes to your health, you call the shots. If something doesn’t ‘feel right’ in your body it’s up to you to advocate for yourself and ask for more testing.

The above tests are basic blood tests. In Australia you can speak to your GP about ordering these tests. Some others that you might like to consider are:

• Prolactin
• A full thyroid panel (TSH, T4, T3, RT3, TPO, Tg Ab)
• Free testosterone
• DHEA-S
• Fasting insulin
• Hba1C
• Along with key nutrients like Vitamin D, zinc, iron studies, B12 and iodine
  

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