Medical investigation unit (metabolic medicine)

This unit carries out specialised tests for consultants, GPs and midwives, including synacthen tests, urea breath tests, and glucose tolerance tests, which can be found below. 

The unit is under the supervision of Dr Hervey Wilcox, consultant, and is staffed by clinical nurse specialists.

Location and contact details

First floor, C Block, St Helier Hospital

Telephone: 020 8296 4340

Having a urea breath test

Your doctor has requested you to take this test to determine if you have a bacterium called helicobacter pylori (H.Pylori) which is sometimes found in the stomach.

It is important that you inform your doctor of any medical condition that you may think will interfere with the test

Test procedure

It is important that you follow the instructions in order to receive a correct test result:

  • You must fast overnight before the test; you may drink water
  • Do not have breakfast, coffee, tea, fruit, biscuits
  • Do not take the following medication before the test:
    • Antibiotics, eg penicillin, for 28 days before the test
    • Proton Pump Inhibitors, eg Omeprazole, Lansoprazole, for 15 days before the test
    • Antacids white medicine, eg Gaviscon or Malox, for 12 hours before the test.

The test takes 10 minutes, using the following procedure:

  1. You be asked to provide two breath samples into two blue topped test tubes. The stopper is unscrewed from the tube. Breathe gently through the straw and slowly pull out the straw while breathing into the tube. As soon as the straw is withdrawn the cap is immediately placed on the tube. It is not necessary to blow hard into the tubes - please breathe normally. The procedure is then repeated with the same straw into the second blue topped tube. The straw will then be discarded.
  2. You will then be asked to swallow a tablet containing urea with a glass of water.
  3. Wait for 10 minutes in an upright position (either standing or sitting)
  4. After 10 minutes, you will be required to collect a further two breath samples in the red topped tubes using the same procedure as above. A second straw will be provided for these samples.

Your doctor who requested the test will inform you of the result of your test. 

Side effects

Like any medications, the urea tablet may rarely cause some side effects, such as stomach discomfort and fatigue.

If you experience any unusual or unexpected symptoms talk to your doctor. The test will not affect your ability to drive or use machinery.

Having a synacthen test

What is a synacthen test?

A synacthen test establishes whether your body is producing enough of the steroid hormone cortisol. Cortisol is needed to keep blood sugar levels stable, look after blood pressure, and for our metabolism, immune system and fluid level balance.

If you do not have enough cortisol, you will probably have felt tired, weak and irritable.

You will be given an intravenous injection in order to assess your cortisol production. ACTH is a hormone secreted by the pituitary gland to control the adrenal gland's production of cortisol. ACTH or synacthen is injected to assess your adrenal function.

The test takes approximately one hour. You may eat and drink normally before the test.

What you can expect

On arrival at the medical investigation unit (MIU) we will insert an intravenous cannula (tiny tube) into a vein in your arm. You can then relax for approximately 30 minutes before we start the test to allow the stress hormones to return to their resting state.

After this rest, we take a sample of blood from the tube and inject synacthen into the same tube. We then take one more blood sample 30 minutes later. The cannula is removed, and you will be offered tea, coffee and biscuits.

Side effects

Occasionally patients feel light headed or dizzy soon after the injection, but this passes within a few minutes.

Extended synacthen test

Sometimes, when you have been taking steroids, your doctor may request an extended test. If you are on steroids, you will be advised either to change to dexamethasone or to stop taking your steroids for three days prior to the test.

  • For prolonged steroid use, a synacthen test will need to be performed over three consecutive days
  • If steroid use has not been prolonged, a one day extended synacthen test will be required, where  blood tests are taken over eight hours on one day and further blood tests the following morning.

Having a glucose tolerance test

This test excludes or confirms the diagnosis of diabetes.

For three days prior to the test you must eat a high carbohydrate diet. The following foods give one portion of carbohydrate. You should eat at least 10 of these portions spread across the day.

Bread (white/brown/wholemeal) 

  • 1 small or 1/2 large roll
  • 1/2 small pitta bread
  • 1/2 6" chapatti
  • 1/2 teacake
  • 1/2 English muffin
  • 1 crumpet
  • 1/2 bagel

Breakfast cereals 

  • 1 Shredded Wheat/Weetabix
  • 25g (4 tbsp) high fibre cereal
  • e.g branflakes
  • 20g (2 tbsp) porridge oats


  • 20g uncooked
  • 75g cooked


  • 20g uncooked
  • 100g cooked


  • 15g uncooked (1 tbsp)
  • 50g cooked


  • 100g raw/boiled/mash
  • 50g roast/chips/baked


  • 1 1/2 digestive/hob nobs
  • 3 digestive fingers
  • 3 rich tea
  • 2 crackers, eg Ryvita
  • 1 cereal bar


  • 1 apple, pear, orange or firm banana
  • 2 kiwisfruit, satsumas or plums
  • 20g dried fruit
  • 100g fruit salad
  • 4 fl oz. (110 ml) fruit juice


  • 1 pot dried fruit flavoured or plain yoghurt
  • 1/4 large tin of low fat rice pudding (110g)
  • 1/3 packet (made up) sugar free whip.


  • 1 small packet crisps
  • 1/2 pint milk

Example of day's intake (portions)


  • 2 weetabix with milk (2)
  • 1 slice toast (1)
  • 1 fruit juice (4 fl.oz/110 ml) (1)

Light meal 

  • 2 slices bread/sandwich with ham/cheese/fish (2)
  • Fruit (1)
  • Crisps (1)


  • 1 1/2 digestive biscuit (1)

Main meal 

  • Meat or fish
  • 3 egg size potatoes (1)
  • Vegetables

Total: 10

You may have more starchy foods than this, please try not to have less.

On the night before the test

After 10pm the night before the test please do not have anything to eat and only plain water to drink, so that you arrive for your test fasting.

The test

The test will take about two hours. When you arrive for the test a blood sample will be taken. You will be given a glass of glucose to drink. A further blood sample will be taken after two hours. During the two hours you can drink plain water, but should not eat or smoke.

Once the test is completed, the results will be sent to your doctor.

Side effects

Occasionally patients feel light headed or dizzy about half an hour after drinking the glucose. This passes very quickly. As the test takes two hours to complete, please bring something to read ordo. You will be required to remain in the unit for the duration of the test. As space is limited we regret that it is not possible to bring a child or relative with you.

If you are unable to attend, please call our pathology laboratory at Epsom on 01372 73 5735 ext 6095 as soon as possible so that your appointment can be offered to someone else.

If you have any questions or problems regarding the above, please do not hesitate to contact us.


  • Follow the high carbohydrate diet for three days before the test
  • Make sure you arrive for the test fasting
  • Bring something to read.


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