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Hashimoto’s and Fatigue: 3 Tips to deal with Pernicious Anemia

by | May 30, 2022 | Symptoms

Hashimoto’s tends to come with debilitating fatigue, weakness, and brain fog. Worse yet, often getting on thyroid hormone medications doesn’t take away all of these symptoms. This is when you want to look at other issues like pernicious anemia, which can cause similar symptoms.

Up to 55% of Hashimoto’s patients have pernicious anemia due to a vitamin B12 deficiency! [1] In this article, we’ll cover what pernicious anemia is, how to know if you have it, and what you should do about it.

What is pernicious anemia?

Pernicious anemia (PA) refers to a vitamin B12 deficiency that happens despite eating enough B12. Pernicious anemia develops because your body cannot absorb the B12 you eat, due to one of the following factors:

  • Low stomach acid
  • Low intrinsic factor, a protein essential for B12 absorption
  • Stomach inflammation

How is B12 Absorbed?

Vitamin B12 requires many steps to absorb, including:

  1. Stomach acid and enzymes release B12 from meat or other animal-based food
  2. B12 binds to a protein called intrinsic factor in the stomach
  3. B12 bound to intrinsic factor travels to the lower small intestine and then gets absorbed

Parietal cells, a type of specialized cells in your stomach, produce intrinsic factor and stomach acid. If something happens to these cells, then you don’t make enough acid or intrinsic factor, you can develop pernicious anemia.

What Causes Pernicious Anemia and How is it Linked to Hashimoto’s?

Pernicious anemia can present very similarly to Hashimoto’s. They also have similar risk factors and triggers. So, if you have Hashimoto’s and are still struggling to get your symptoms under control, you should get checked for pernicious anemia and B12 deficiency.

Low stomach acid 

Low stomach acid can reduce B12 absorption. Causes of low stomach acid may include:

  • Medications (antacids) 
  • Stress
  • Aging
  • Low-thyroid function
  • Gastric bypass
  • Eating when stressed or in a hurry


If you have one autoimmune condition, you’re much more likely to have another one especially if the inflammation isn’t well-managed. So, if you already have Hashimoto’s, you are more likely to develop antibodies that interfere with B12 absorption [2-3]. Conversely, many people who started with autoimmune gastritis are at 3 – 8 times greater risk to develop autoimmune thyroid condition [2-4].

These antibodies can bind to intrinsic factor, block B12 absorption, or attack the parietal cells. When autoimmune antibodies attack parietal cells, it inflames the stomach, causing gastritis.

Helicobactor pylori

Helicobactor pylori (H. pylori) is a common bacteria that infects the stomach. The bacteria can also inflame and damage your stomach lining, reducing both stomach acid and intrinsic factor production.

H. pylori can also trigger autoimmune attacks on your parietal cells. Your immune system may confuse your parietal cells with the similar proteins in H. pylori, and then attack them both [5-6].

How Pernicious Anemia Can Make Hashimoto’s Worse

Pernicious Anemia can aggravate Hashimoto’s symptoms

Hashimoto’s and PA have some very similar symptoms. Both include fatigue, muscle weakness, brain fog, depression, and tingling in the extremities. So, you want to test for vitamin B12 deficiency and anemia, especially if you are on thyroid medications and these overlapping symptoms remain unimproved. 

You may feel better once it is clear what symptoms were caused by which condition.

Unmanaged Hashimoto’s can reduce stomach acid, so you absorb less B12. This means you want to address both conditions.

Elevated Homocysteine

Both pernicious anemia and Hashimoto’s can each increase homocysteine. Homocysteine is a toxic amino acid that can increase your cardiovascular risk. 

Aside from symptoms of B12 deficiency above, high homocysteine can contribute to depression and fertility problems [7-8], which affect many Hashimoto’s patients.  

How is pernicious anemia diagnosed?

PA often develops slowly over time, since your body has a B12 store that can last a few years. You may have no symptoms until your deficiency becomes very bad. Sometimes people will simply get used to the symptoms and think they’re normal.

When symptoms do show up, they can be in any of the areas listed here.

  • Changes in red blood cells: paleness, fatigue, shortness of breath, increased heart rate, lightheadedness, and decreased mental and physical function
  • Digestive: diarrhea, bloating, loss of appetite, weight loss
  • Nervous system: peripheral neuropathy and/or paresthesia (numbness and tingling), weakness, trouble walking, forgetfulness, psychosis
  • Cardiovascular: shortness of breath, palpitations, edema (swelling)

Thankfully, conventional medicine recognizes pernicious anemia, so you can simply speak to your doctor and get a blood test for a diagnosis.

Your doctor will order common lab tests including Complete Blood Count (CBC) and vitamin B12 level. They will look at the report for specific signs of anemia and cell changes. 

If you have anemia from B12 deficiency, your red blood cells enlarge (megaloblastic) and decrease in number (anemia).  If B12 is on the low end of the normal range, your red blood cells look normal, and B12 deficiency is highly suspected, your doctor may also order the methylmalonic acid (MMA) test since it is a more sensitive test for B12 deficiency.

To pinpoint the exact reason for B12 deficiency, your doctor may also order tests for anti-intrinsic factor and parietal cell antibodies.

Pernicious Anemia Treatments

Pernicious anemia treatments involve replenishing your B12 levels until they reach normal levels. This may require high doses. Then, the goal is to keep them at the normal range by whatever means necessary. 

Sublingual (under the tongue) B12

Some B12 forms can be absorbed under the tongue as tablets or liquid drops. Depending on the severity of the deficiency, sublingual B12 may work to maintain B12 levels once your B12 reaches normal ranges. However, for frank B12 deficiency, you may need a vitamin B12 injection or intravenous infusion.

B12 Injection

Some people need intramuscular B12 injection. They tend to inject inactive forms such as cyanocobalamin or hydroxocobalamin, and then allow the body to activate them. One of the two active forms of B12, methylcobalamin, is also readily available for intramuscular injection. Your doctor can help you find out the combination of B12 forms that work best for you.

IV B12

In the most serious cases, B12 can be given in a clinical setting via an intravenous (IV) infusion.

Intrinsic Factor

Some B12 supplements also include intrinsic factor in the formulation. This may be helpful in maintaining B12 levels once your levels are normalized with injection or IV.

Betaine HCl 

Betaine HCl can help increase your stomach acidity when taken with meals [9]. It helps with both B12 absorption and many other aspects of digestion.


If you have Hashimoto’s and your symptoms aren’t under control, even with thyroid medications, you should speak to your doctor about screening for Pernicious Anemia. Thankfully, if caught early enough, you can easily restore your vitamin B12 levels and prevent further damage from B12 deficiency. Also consider seeing a functional medicine doctor to investigate a potential H. pylori infection or low stomach acid, as well as more advanced thyroid testing. 


  • Hashimoto’s often comes with Pernicious Anemia
  • If your symptoms are not better despite thyroid medications, it could be pernicious anemia.
  • H. pylori can cause pernicious anemia.
  • Treatment for pernicious anemia requires repleting low B12 levels and then maintaining healthy levels
  • Betaine HCL and intrinsic factor supplements may help with B12 absorption from food


How do you know if you have a Thyroid Issue?

Learn the 10 telltale signs you’re struggling with a thyroid issue.

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Article References

1  Antonijević, N., Nesović, M., Trbojević, B. and Milosević, R. (1999) [Anemia in hypothyroidism]. Med. Pregl. 52, 136–140.

2 Tozzoli, R., Kodermaz, G., Perosa, A. R., Tampoia, M., Zucano, A., Antico, A. and Bizzaro, N. (2010) Autoantibodies to parietal cells as predictors of atrophic body gastritis: a five-year prospective study in patients with autoimmune thyroid diseases. Autoimmun. Rev. 10, 80–83.

3 Rodriguez, N. M. and Shackelford, K. (2021) Pernicious Anemia. In StatPearls, StatPearls Publishing, Treasure Island (FL).

4 Lahner, E., Centanni, M., Agnello, G., Gargano, L., Vannella, L., Iannoni, C., Delle Fave, G. and Annibale, B. (2008) Occurrence and risk factors for autoimmune thyroid disease in patients with atrophic body gastritis. Am. J. Med. 121, 136–141.

5 Uibo, R., Vorobjova, T., Metsküla, K., Kisand, K., Wadström, T. and Kivik, T. (1995) Association of Helicobacter pylori and gastric autoimmunity: a population-based study. FEMS Immunol. Med. Microbiol. 11, 65–68.

6 Chmiela, M. and Gonciarz, W. (2017) Molecular mimicry in Helicobacter pylori infections. World J. Gastroenterol. 23, 3964–3977.

7 Folstein, M., Liu, T., Peter, I., Buell, J., Arsenault, L., Scott, T. and Qiu, W. W. (2007) The homocysteine hypothesis of depression. Am. J. Psychiatry 164, 861–867.

8 Ocal, P., Ersoylu, B., Cepni, I., Guralp, O., Atakul, N., Irez, T. and Idil, M. (2012) The association between homocysteine in the follicular fluid with embryo quality and pregnancy rate in assisted reproductive techniques. J. Assist. Reprod. Genet. 29, 299–304.

9 Litvak, Y., Byndloss, M. X. and Bäumler, A. J. (2018) Colonocyte metabolism shapes the gut microbiota. Science 362.


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