Vitamin B12: When It Is Actually Low and How to Know

Vitamin B12 is measured with a blood test, and it is worth measuring before you start injecting it. The test is inexpensive, walk-in, and it keeps you from spending months treating something that was never B12.

Fatigue has many causes. B12 is one. Thyroid is another. Iron-deficiency anemia is another. They look a lot alike, and only lab work separates them.

What does B12 do?

According to the U.S. National Institutes of Health, B12 is required to form red blood cells, for DNA synthesis, and for normal nervous system function.

Your body does not make it. It comes from diet — meat, fish, eggs, dairy and fortified foods — and is absorbed in the intestine with the help of a stomach protein. When that absorption fails, eating more does not fix anything, and that is where injections make sense.

What are the symptoms of deficiency?

The ones the NIH describes:

• Fatigue and weakness that rest does not improve
• Tingling or numbness in hands and feet
• Balance problems
• A sore tongue or mouth ulcers
• Trouble concentrating, memory lapses
• Megaloblastic anemia, visible on a complete blood count

The tingling is the most specific. Fatigue is the least — twenty different things cause it.

Who is at higher risk?

• Adults over 50. Absorption drops with age even on a good diet.
• Vegetarians and vegans, and anyone eating very little animal protein.
• People with stomach or intestinal surgery, including bariatric surgery.
• People on metformin for diabetes over several years.
• People on omeprazole or similar medication long term.

If two or more of these describe you, testing once a year is reasonable.

Why test before injecting?

Because if your fatigue is not from B12, injections will not lift it, and meanwhile the real cause goes untreated.

A single draw can check B12, complete blood count, thyroid and glucose — the four most common causes of "I have been exhausted for months". That is done under blood tests and lab work, walk-in and with no prior doctor's order. If thyroid comes back off, we follow it there: thyroid testing and treatment.

And if it really is low?

Treatment depends on the cause. If the problem is diet, an oral supplement is sometimes enough. If the problem is absorption, the injectable route makes sense, because it bypasses the intestine.

That decision — whether you need it, in what form, and how often — is made by our medical team with your results in hand, not before. We administer the injections at the clinic.

Where to get it done

934 E Tidwell Rd, Houston, TX 77022, north Houston. Open seven days a week, 9 AM to 9 PM, walk-in, no insurance needed. Ask the price of the test before the draw.

If you have been tired for months and have never had lab work done, start there. It is the cheapest thing you can do and the one that tells you the most.