Preparing for your Blood Test

All your questions answered

If the phlebotomist is delayed due to reasons beyond their control, you will receive a phone call to advise an estimated time of arrival. If this is not convenient, we will be happy to reschedule or refund you the full amount.

It is imperative you have your blood test form that your GP gave. Without this, the phlebotomist will be unable to know which bloods to take and the laboratory will not know which test to conduct. Please make sure you have the form with you to give to the phlebotomist when they arrive.

Usually a 12 hour fast is required prior to the blood test with nothing to eat or drink. However, it is acceptable to drink plain water right up until your test and you can take your medications if required.

Fasting times: Glucose – 10 hours; Lipids – 12 hours

Diabetic fasting: If you have diabetes and are on tablets or insulin, please do not have your medication until after your blood test. If you are worried about this, please speak to your GP for further advice.

Digoxin levels: bloods should be taken 6-8 hours after you have taken your digoxin dose.

Iron test: ideally avoid taking any iron tablets 24 hours before your blood test
Lithium levels: should be taken 12 hours after the last dose.
For any other drug levels, please ensure you check with your GP about the correct time of taking the blood test to check drug levels.

If you are taking Warfarin or Aspirin, please inform the Phlebotomist taking your blood, immediately prior to your test, as these tablets may affect the time you take to stop bleeding after the test.

We can usually carry out the majority of blood tests that your GP will request, however there are a few tests that we cannot do and your GP should have informed you which tests will need to be carried out at the hospital.

Tests that cannot be done by Blood Tests at Home include:
Renin; Aldosterone; Parathyroid (PTH); Insulin; C-Peptide; Gastrin; Calcitonin; Homocysteine; Lactate; Ammonia; Vasopressin; Cryoglobulin; IGF-1; Vitamin A/B1/B2/B6/E; Chromosomes; TPMT

PLEASE NOTE: THESE BLOODS ARE RARELY REQUESTED BY A GP but please contact us if one of these tests are stated on your form

We do blood tests on all ages however we do ask you to note that in babies and children the technique of holding them is vital to achieving a successful sample.

To ensure the best possibility of getting an adequate sample, we require a second person to assist you, in addition to the phlebotomist. This is because some children can be very strong and any movement can displace the needle requiring repeated attempts.

Correct restraining of the child/baby will mean less pain and distress to the child/baby and a smoother collection of the required quantity of blood.

On some occasions if a first attempt has failed, we reserve the right to refuse a second attempt as the phlebotomist may feel a second attempt be better carried out in the hospital environment.

We are unable to use numbing spray or creams as these take too long to take effect.
However, if you wish to use a numbing cream, it can be purchased at most pharmacies. The cream should be applied to the front of the elbow (antecubital fossa) of both arms about 1 hour before the due appointment time. The cream is held in place with a clear dressing.

Please note that the child may still be distressed due to the anticipation of the test and the restraining process. Firmly holding the child is still the best way to achieving a successful sample with or without the numbing cream.
Ask Your pharmacist for: EMLA cream.

What happens if there is a problem collecting the blood?

In some instances, it is difficult to collect the blood in enough quantities to analyse. This can happen if for example a child is wriggling too much, a needle phobic patient is unable to hold still or infrequently due to veins being too small to collect enough blood.

If this is the case, the phlebotomist will indicate this to yourself and mention this in her report, so the management team at ‘Blood Tests at Home’ are aware that the bloods were unable to be collected or may be reported by the laboratory as insufficient.

If this is the case, please contact us at ‘Blood Tests at Home’ and we can discuss the next steps.

Call us on 020 3039 3344 or email on

Our secretary is available from Monday to Friday 9am to 5pm.

If our secretary is otherwise engaged when you call, please leave a message with your contact details and we will aim to contact you back on the same working day within our office hours.

If you need to contact us outside these hours, please leave a message on the answerphone and we will do our best to return your call as soon as we can within office hours.

You can download this guide for your record

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