Blood testing is needed to ensure that your medication dosages are effective and your hormone levels are in the right range. Too low and you won’t experience the changes you want to see, and too high puts you at risk of side effects.
The timing of blood tests is important for making sure the results are helpful for monitoring your health and making sure you're getting the right medication for you.
Medication Differences
Pills
- Pills are usually taken daily, providing a continuous, consistent release of hormones.
- Blood tests can be performed at any time during the day when taking pills since hormone levels remain relatively stable throughout the day.
Patches
- Patches are usually worn for several days (e.g., 3 to 7 days) and provide a continuous release of hormones.
- Blood tests are best taken half way between patch changes.
Gels/Creams/Sprays
- These are applied daily and provide a consistent daily dose.
- A blood test is best taken 4-6 hours after application.
- Don't take blood from an area of skin that has been in contact with gel or cream to avoid contaminating the blood test and getting an abnormally high result.
- If possible, use gloves to apply your medicine in the week leading up to your blood test.
Injections
- Injections, deliver a large amount of hormones and create peaks and troughs in hormone levels.
- Blood tests should be conducted just before the next injection is due. This timing provides the most accurate representation of the hormone’s lowest concentration, ensuring safety and efficacy.
Timing Blood Tests for Injections
If you're taking injections, you should schedule your blood tests based on your trough levels. Here’s how it works:
- Frequency of Injections: Determine the frequency of injections, which could be weekly, bi-weekly, monthly, or three-monthly depending on the medication prescribed.
- Trough Levels: Schedule your blood test to be just before the next injection is due. This captures the hormone’s lowest concentration, which helps keep it within the desired range throughout the entire dosing interval.
- Consultation: You can speak with us to figure out the ideal timing for your blood tests based on your medication, dosage, and injection schedule.
Do I need to fast before my blood test?
This depends on the specific tests you are having. Some blood tests do require fasting, while others don't. Here are some general guidelines:
- Hormone Level Testing: Hormone level tests, such as those for testosterone or oestrogen, don't require fasting. You can have these tests done at any time during the day.
- Liver and Kidney Tests: These tests don't require fasting, You can have these tests done at any time during the day.
- Haematocrit: This test doesn't require fasting, You can have this test done at any time during the day. This test is included in the Full Blood Count.
- Lipid Profile: These typically require fasting for 9-12 hours before the test.
- Glucose Testing: If you’re having a fasting blood glucose test, you will need to fast for at least 8-12 hours before the test to get accurate results. Check which type of glucose test you're having to see if you need to fast.
Contamination with Gels
Hormone gels can contaminate the blood sample if testing is done too soon after application or on a surface where you apply gel. Make sure you collect your blood sample away from the site where you apply your gel.
To reduce the risk of contamination, wait two hours after applying the gel before drawing blood. Take blood from a site away from where you apply gel. For example, if you've been using your right hand to apply gel to your forearms, take the blood sample from your left hand.