Iron tests

[Tjqui00]

I spoke to my doctor today as I was concerned about my ferritin of 48 which was tested on 8th May, after reading that with high auto antibodies, which I also just found out I have, my ferritin should be over 100 to not have iron deficiency. She booked me in for iron studies tests next Wednesday at 11.25 am and said I didn’t need to fast, but I read online I do need to. They have an appointment tomorrow at 8.15 am I can have if not. Do you need to fast before iron studies tests? Would I better waiting an extra week until next week rather then tomorrow as I only had ferritin tested on 8th May or won’t it make much difference?

[humanbean]

Do you need to fast before iron studies tests?

I always eat my dinner the night before any iron testing, then stop eating from about 10pm - midnight until the blood is taken in the morning. I drink water freely during this time - being dehydrated will distort results for all sorts of blood tests. I also avoid eating iron-heavy meals for a day or two before the testing. For example, I wouldn't eat liver in the couple of days before a blood sample is taken for testing.

If you look up some lists of high iron foods be wary of what they are telling you.

I found a list once which said that thyme was a very high iron food, and liver was near the bottom of the list. But it was giving me the quantities of iron in mg/100g of each item in the list. I can guarantee that I will never eat 100g of thyme in one sitting in my life! But since I eat meat I could imagine eating 100g (3.5 ounces) of liver at one sitting if I was really, really hungry, although I don't eat liver very often as a general rule.

I'm not suggesting that you rig the result of the iron tests by avoiding iron completely. That would do you no good at all, and would distort your medical history to no purpose. Just eat meals that would commonly appear on your plate in a normal week but without the really iron-heavy meals.

[SeasideSusie Remembering]

Tjqui00

I have come to the conclusion that doctors know very little about fairly basic facts, maybe they've forgotten them.

Read what the NHS website says about fasting blood tests:

nhs.uk/common-health-questi...

Common fasting blood tests

Examples of blood tests that may require you to fast include:

* a fasting blood glucose test (used to test for diabetes) – you may be asked to fast for 8 to 10 hours before the test

* an iron blood test (used to diagnose conditions such as iron deficiency anaemia) – you may be asked to fast for 12 hours before the test

For more information about a wider range of blood tests, go to Lab Tests Online.

and if you go to Lab Tests Online they say this:

labtestsonline.org.uk/tests...

Test Preparation Needed?

Your doctor may request that you fast for 12 hours prior to some iron blood tests. In this case, only water is permitted. You should not take any iron tablets for 24 hours before the test. Iron is absorbed rapidly from food or tablets, and can make your blood iron levels falsely high.

Some other sources:

blood.london/blog/fasting-b...

3. Iron tests

Iron tests determine if the mineral iron in the blood is too low or high. It helps your doctor to diagnose iron-related conditions like anaemia. Fasting is required for at least 12 hours before the test to get an accurate result.

Iron is present in different types of food, and it is easily absorbed into the blood. Eating any food before the test can give wrong results with a very high level of iron. It is also necessary to avoid iron and mineral supplement for at least 24 hours before the test.

medicalnewstoday.com/articl...

Iron blood test

An iron blood test measures the levels of the mineral iron in the blood. This test helps identify conditions that are caused by a lack of iron in the blood, such as anemia.

Iron is contained in some types of food and is absorbed very quickly from food into the blood. Therefore, if a person eats food before the iron blood test, the results may show inflated levels of iron.

To ensure accurate results, a person should fast from midnight the night before the test until after the test is done.

This latter link also mentions liver function test requires fasting, as does electrolyte and kidney tests (amongst others). I have a these done regularly and have never been told to fast, I already knew LFTs need to be done fasting so I ensure I do so, but it just goes to show that doctors, and even the nurse taking the blood, don't mention it.

The iron studies test should be more than just ferritin, hopefully it will be the full iron panel consisting of serum iron, total iron binding capacity (or transferrin), saturation percentage plus ferritin.

[Tjqui00 in reply to SeasideSusie]

I did fast before my last one so I probably should again. Probably should have the blood test tomorrow as they’d the only other appointment they have, but I only had a ferritin test done 2 weeks ago and that’s not enough time for that to change.