I’m wondering what the interplay is between our thyroid hormone replacement medication and vitamin B12. Does B12 affect how thyroid medication is absorbed? Does sufficient B12 make our thyroid medication work better? If you have high B12 levels can you take less thyroid replacement?
Thanks!
Donna5658,
The connection is the gut. People with low thyroid hormone often suffer absorption issues so VitB12 deficiencies are extremely common. Many Hashi sufferers also have other autoimmune conditions such as PA, and any absorption issues will also effect absorption/conversion of thyroid hormone.
The further implications are far reaching, and could be seen as raised homocysteine when inadequate VitB12 impairs it conversion to methionine and the reduced clearance rate caused by low thyroid thyroid hormone will elevate homocysteine further.
Too little thyroid hormone to stimulate lipolsis (beakdown of cholesterol) & clear excess LDL with raise cholesterol levels. Homocysteine further stimulates the production & secretion of cholesterol so these levels will increase further.
Many symtoms of VitB12 deficiency & low thyroid hormone mimic each other. Often the best areas to address first regarding nutrient deficiencies are the gut & the liver. When I refere to low thyroid hormone it does not necessary relate to the circulating levels in our blood which could be good but the amount that is effectively working (ie converting, uptake, excretion, etc).
Being under medicated and therefore still hypothyroid will frequently result in low stomach acid
Low stomach acid leads to low nutrient absorption and low vitamin levels
Extremely common to have low vitamin D, folate, ferritin and B12 and need to supplement to improve vitamin levels
Hi Slow Dragon, will the B12 be improved once we are correctly medicated with thyroxine? Or is the harm to our stomach irreversible?
Depends on how good your conversion of Ft4 to ft3 is
If you have poor conversion (many with Hashimoto’s do) ….then Ft3 will remain low
Low Ft3 tends to result in low vitamin levels
Also great answer! Thanks for clearing this up! Is there a threshold (still in the normal range) below which one doesn't want to fall? “Normal” range is extremely broad for B12. In other words, is higher better? Also would low stomach acid or low thyroid level result in low absorption of iron? I have normal ferritin but plummeting iron (bottom of normal range). Hematocrit and hemoglobin also normal.
Donna5658,
Yes, gut absorbtion issues will impair iron levels and serum iron is usually the first to decrease. Ferritin will be shifted back into the blood stream for use and this is when storage levels then become low as can not be replaced.
As time goes on ferritin levels become harder & harder to raise as the mechanisms that protect us from having too much or too little iron become skewed. Low ferritin and low/medium levels of serum iron are very common on the forum.
Marz has answered re VitB12 below.
B12 molecules in food are bound up in Intrinsic Factor in the stomach - secreted from the Parietal cells. This protects the B12 on its onward journey into the duodenum and beyond to the Terminal Ileum. Here it is netabolised, returning via the bloodstream for storage in the liver.
Many thyroid folk have gut issues that prevent this happening efficiently - myself included. >500 is a good level to prevent cognitive decline ....
Thank you! Mine is in the low 400s at the moment so I will shoot for 500. I have been plagued by GERD for the last couple of years and have been on an H2 blocker (I am attempting to wean off) for the last three months. That obviously is contributing to low stomach acid and impaired absorption of vitamins and minerals, not to mention my thyroid medication (Armour plus a bit of Synthroid). I am eternally grateful that this group exists to help us put the pieces of our individual healthcare puzzles together.
H2 blocker is to treat high stomach acid patient.info/digestive-heal...
Low stomach acid can be a very common hypothyroid issue
Thousands of posts on here about low stomach acid
healthunlocked.com/search/p...
Web links re low stomach acid and reflux and hypothyroidism
nutritionjersey.com/high-or...
articles.mercola.com/sites/...
thyroidpharmacist.com/artic...
stopthethyroidmadness.com/s...
healthygut.com/articles/3-t...
naturalendocrinesolutions.c...
meraki-nutrition.co.uk/indi...
huffingtonpost.co.uk/laura-...
lispine.com/blog/10-telling...
Protect your teeth if using ACV with mother
healthunlocked.com/thyroidu...
Ppi
Omeprazole will lower vitamin levels even further
gov.uk/drug-safety-update/p...
webmd.com/heartburn-gerd/ne...
pharmacytimes.com/publicati...
PPI and increased risk T2 diabetes
gut.bmj.com/content/early/2...
Thank you for the comprehensive answer!
Under active thyroid and B12
Lichen sclerosis and B12 connection?
Loading dose b12 + thyroid test
Should Thyroid Patients Self-Medicate?An Editorial from Mary Shomon 
