Don't count on your doctor to help you with that. Doctors know nothing about nutrition - even less than they know about thyroid! So, you've got to do it yourself.
Serum ferritin level 50ng/ml (10-322) - ferritin should be half way through it's range. You could discuss this result with your GP and see if he will offer an iron supplement. If he won't then you can buy Ferrous Fumarate from Amazon and take one tablet twice a day with 1000mg of Vit C to aid absorption and help prevent constipation. Finish the packet (usually 84 tablets) then re-test. Too much iron is as bad as too little. Take iron 4 hours away from thyroid meds (if you take any) and other meds and supplements as it affects their absorption. Eating liver once a week will also help raise ferritin level.
Serum vitamin B12 level 307ng/L (211-911) - Anything under 500 can cause neurological problems. Recommended level is top of range, 900-1000. You could get some Solgar or Jarrows sublingual methylcobalamin lozenges 5000mcg and take one daily, dissolve under the tongue for absorption directly into the bloodstream, don't chew or swallow as stomach acid destroys it. You could reduce dose to 1000mcg daily after a couple of months and stay on that dose as maintenance.
Serum folate level 2ng/ml (5.4-24) - very low. This should be at least half way through it's range. A B Complex is needed when supplementing with B12. You can supplement with Thorne Basic B or Jarrows B Right, both contain 400mcg methylfolate which will help raise folate level. Eating leafy greens also helps.
B vits should be taken in the morning, no later than lunchtime as they are stimulating.
Don't start all supplements at once. Start with one, give it a week or two and if no adverse reaction then add in the second one and again give it a week or two. If no reaction then add in the next etc. This way if you have a problem you will know what caused it.
Have you had Vit D tested? As everything else is low there's a good chance Vit D will be too.
This is the order I would do it. I would start with the iron supplement and you'll need to start Vit C as well as it aids absorption. Give it a week or two and if no adverse reaction then add in the B12. Give it a week or two and if no adverse reaction then add in the B Complex.
As all your other levels were low, it's very likely that your Vit D is also. As this is just as important as the others I urge you to get it tested privately with a blood spot fingerprick test from City Assays, costs £28 vitamindtest.org.uk/index.html The recommended level is 100-150nmol/L so if yours is less then come back for suggestions for supplementing.
And as Eddie has suggested below, testing antibodies will be very helpful. Ask your GP, he may agree. The NHS only seems to do TPO but you can be negative for TPO and positive for TG and the NHS rarely tests that. You can get them tested privately with Blue Horizon bluehorizonmedicals.co.uk/P...
I strongly encourage you to get your Thyroid Peroxidase (TPO) and Thyroglobulin (TG) antibodies tested. If you have thyroid autoimmunity, it is possible that it is being precipitated by gut enteropathy ("leaky gut") and/or gut dysbiosis. Just the fact that you have nutritional deficiencies, makes me suspicious that you are not absorbing well; it is a bit unusual for a male to show up with iron deficiency. Take a look at Tom O'Bryan's youtube video on "The Autoimmune Fix". O'Bryan explains how food sensitivities (esp. gluten, soy, yeast, dairy) can mess up the gut, precipitating autoimmunity. This is a double whammy to your digestion: a damaged gut can't absorb well, and thyroid autoimmunity precipitated by a damaged gut further degrades digestion, because T3 (required for good digestion) level drops.
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