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How to Use GenderGP Home Blood Test Kits


You will need to do these tests “fasting” i.e. nothing to eat from 9pm the night before doing the test. Then do the test in the morning and post back the same day.

Please try to make sure the tests are carried out at the appropriate time depending on your medication:

Testosterone injections: 2nd week of the injection.
Testosterone or Oestrogen gel: 4 – 6 hours after the gel is applied.
Oestrogen tablets: At any time.
Oestrogen patches: The day after a patch change.
Blockers: At any time.

Please make sure that tests are carried out in the morning and posted back the same day.

If you are using gels, make sure that gel won’t have been near the fingers you use for the test for at least 48 hours before the test otherwise you may get contamination and an abnormally high test result.

Please follow the instructions given in the pack as closely as you can. However, for additional help – when you get to step two try bathing your hand in some warm water before pricking your finger, to encourage the blood well into the fingertips. You can also take a warm shower or do some gentle exercise beforehand to encourage a good flow, as well as making sure you are well hydrated. Let gravity help by standing up to take your sample. If the blood flow stops, wipe the area with a clean tissue. If it still does not flow use a spare lancet and prick another finger.

You may receive more than one sample tube – you will need to fill all tubes to the second line. You may find it better to do one from one finger and the other from another, this limits the chance of damage to the cells. There is an excellent instruction video

Make sure you keep the form in the grey pre-paid envelope and send it with your sample to our laboratory in London. They will then process the sample and send us the results.

The details on the form must match the details on the tube label or the lab will not process the sample.

It is very important you only post the sample back between Monday and Wednesday. Although the lab operates 24/7, the Royal Mail doesn’t and the sample may become unusable if it sits untested for more than a day. If you post the sample back between Thursday and Sunday, the sample is likely to spoil and we will have to charge for a retest.

Most samples are processed without a problem, but there are three common things that can go wrong and mean we need to arrange for a retest, but the laboratory still charge for processing the error sample, and we will need to charge you for a retest sample as well.

  • ‘Sample haemolysed’ – this can happen when you squeeze your finger too hard to get the blood out, and the blood cells are damaged on the way out. Be gentle when squeezing your finger to avoid this.  It can also happen if you shake the tube too hard to mix it.
  • ‘Sample clotted’ – if the blood is allowed to clot in the tube before it is mixed with the liquid in the tube. Gently invert the tube to mix the blood.
  • ‘Insufficient sample’ – always make sure you fill the blood to the line.

Please watch this video as it will really help you to make the most out of your test: