I also take a vitamin B complex which gives 100%NRV of B1, B2, B3, B5, B6, B12, biotin and folic acid. When my levothyroxine was lowered to 100 (to try to increase TSH) my body struggled to use the food I was eating and I ended up with folate deficiency anaemia.
Vit D - your dose is too low. You need 5000iu daily then retest in 3 months. When you have reached the level recommended by the Vit D Council, which is 100-150nmol/L, then you need to find your maintenance dose by trial and error. It may be 2000iu daily, maybe more or less, maybe more in winter than summer so we have to test twice a year to keep within the recommended range.
If you have then your GP should test for B12 deficiency /pernicious anaemia.
According to the book "Could it be B12" by Sally Pacholok, it should be at least 550, and for older people, to help prevent alzheimers, then 900-1000.
There are many people with an original level in the 300s who have B12 injections so a low level can't be dismissed just because it's in range, it's symptoms that are important.
If you don't have any symptoms on that list then you could supplement with sublingual methylcobalamin lozenges along with a good B Complex to balance all the B vitamins.
As for your Folate level, don't let your GP fob you off with "It's only just below range". Ranges are for a reason, not to be ignored.
If prescribed folic acid don't start taking it until further investigation into B12 has been carried out and injections /supplements started as folic acid or Folate in B Complex will mask symptoms of B12 deficiency.
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