If you would like to do your blood tests at home, you can arrange for GenderGP to send you a finger prick kit. This can be ordered via our Help Centre. Make sure that you confirm with GenderGP exactly which blood tests you need done (e.g. full health check, testosterone, oestrogen).

Home testing kits are suitable for most users, and may be preferable if you want to carry out your blood test in your own home at a time of your choosing.

However, a test carried out by a trained phlebotomist will usually have a lower chance of failure. In particular, hormone gel users have a much higher risk of a contaminated blood sample.

The finger prick kit is not suitable for users who require a larger sample. This includes kidney function testing for people on spironolactone, as well as users who require additional monitoring (e.g. for diabetes). In this case you will have to have an intravenous sample taken by a trained phlebotomist.


Here’s how to use your home blood testing kit – but the most important thing is to read the instructions first!



  1. Carefully open the test kit box, as you will need to reuse it later.
  2. First, you should clearly complete the name label. Make sure that the information matches the information on the testing kit order form, and do not put the label on the tube until you have finished collecting your sample. Check that all the components of the testing kit are present.
  3. Wash your hands in warm soapy water and dry them thoroughly with a clean towel.
  4. The protective packing wallet that comes with the test is designed to hold the blood collection tube during the process. Insert the tube into the plastic as shown in the instructions.
  5. Disinfect the collection site with the alcohol swab and dry thoroughly with a clean towel. It is important that the site is completely dry or the blood will not form a droplet. The best collection site is the side of the little finger.
  6. Remove one lancet by twisting and removing the blue stick. If you are unsure about this process, follow the instructions. Position the lancet firmly against the side of the finger, and press the tip against the skin, then activate it. This will pierce the skin and a small drop of blood will warm.
  7. Wipe away the first drop of blood with a clean tissue. Then, holding your arm and hand downwards, firmly massage the side of your hand down to your little finger to encourage blood flow. Carefully ‘milk’ your finger to fill the blood collection tube to the upper line on the side of the tube. If blood flow stops before the tube is full, you can wipe the site with a dry tissue and wait 5-10 seconds for blood drops to reform. Alternatively, you can repeat the process using a spare lancet on the other hand.
  8. Once you have finished collecting, apply the plaster to the collection site to stop bleeding. Screw the cap onto the tube until you hear an audible click. Then, gently invert the collection tube 5 to 10 times. Do not shake the tube as this can lead to a failed sample.
  9. Put the label on the tube, then put the tube in the protective packing wallet as shown in the instructions. Place the protective packing wallet containing the sample(s) and the used lancet(s) inside the test kit box. Then secure the box with the security sticker.
  10. Place the sealed test kit box into the self-addressed prepaid mailer with your request form. Seal it and post it as soon as possible.


If you’re using hormone medication it can affect the results of your blood tests. To ensure you get the most accurate result possible, you should carry out your blood test at the appropriate time depending on your medication as follows:

  • Testosterone injections: take your test two weeks after your injection.
  • Testosterone gel or oestrogen gel: take your test at least four to six hours after applying the gel.
  • Oestrogen tablets: you can take your test at any time.
  • Oestrogen patches: take your test the day after a patch change.
  • Blockers: you can take your test at any time.

You should always try to carry out and post your test between Monday and Wednesday. This is to minimise the chance of delays in the postal service, which could lead to a spoiled sample.

You should also fast before taking your home blood test. This means that from 9pm the night before until after the test you should consume no food and drink only water.

There are a few common errors that can occur with a home testing kit. Here is how best to avoid them:

  • Sample haemolysed. This means that the blood cells in the sample are damaged. It can happen if you squeeze your finger too hard during the collection process, or if you shake the sample too hard afterwards.
  • Sample clotted. This means that the blood has clotted before it has mixed with the anti-coagulant liquid in the tube. To avoid this, gently invert the tube 5 to 10 times after it has been sealed.
  • Insufficient sample. This means there is not enough blood. Always make sure you fill the tube to the line. Do not apply the label until after the collection process.
  • Bottle labeling error. This means the information on the label does not match the information on the order form. Please make sure these match.

If you use oestrogen gel or testosterone gel there is a substantially increased chance of the sample becoming contaminated. This is because trace amounts of gel remaining on the skin can mix with the sample, producing an elevated result.

There are a few ways to minimise sample contamination by gel. You should use a different hand for taking the sample to the hand you normally use to apply the gel, and carefully apply the gel to your inner thighs or very top of your shoulder only. If you wear gloves while applying the gel it will reduce the chance of contamination. You should always thoroughly wash your hands with soap and warm water and dry them with a clean towel after applying gel and before taking a blood sample.

To avoid the need for a retest, you may also want to consider using a local laboratory. We use a service that has over 170 clinics UK wide, and having a trained phlebotomist carry out the test can substantially reduce the risk of contamination.

Here’s a few best practice tips to get the most out of your home blood testing kit and minimise the need for a retest:

  • Always read the instructions in the pack carefully. Check the contents and prepare everything before you start (but remember not to apply the label to the tube until AFTER the collection process).
  • Carry out your test in the morning (Monday, Tuesday, or Wednesday) and post it back the same day. This will ensure it arrives at the laboratory promptly and does not spoil in the post.
  • You can encourage good blood flow by taking a warm shower or doing some gentle exercise. Make sure you are well hydrated.
  • Make sure that you are working with gravity, not against it. Keep your hand and arm pointed downwards for the duration of the test, and carry out the collection standing.
  • Fill all the tubes you receive – you may have up to three tubes in your pack. Return all tubes together and remember to complete and include your form, as without the form the kit will be rejected. It is important to label the bottle exactly as the form is filled out, as if the names do not match the sample will be rejected.


If you have any questions you can visit our blood testing advice page, or contact our Help Centre.


Photo by Testalize.me on Unsplash