Which Tests check Absorption of Vitamin B12?

Published on: Modified on:



Difficulty absorbing vitamin B12 is sometimes caused by pernicious anemia. Chronic fatigue is one of many symptoms of vitamin B12 deficiency- pernicious anemia. In order to test absorption of vitamin B12, some blood tests are required.


What is vitamin B12 deficiency?

Vitamin B12 is a mineral that we absorb from animal products like meat, chicken, fish, eggs, and milk.  Vitamin B12 is essential for your nervous system, red blood cell production, DNA synthesis, and cognitive functioning.  Without it, you might experience symptoms like fatigue, memory loss, depression, tingling in the hands and feet, altered sense of taste, difficulty walking steadily, and decreased motor control. (Absorbing Vitamin B12, a Metabolic Gastrointestinal Journey)

Who is at risk for vitamin B12 deficiency?

Most people will never experience vitamin B12 deficiency.  That is because generous amounts of B12 are stored in your liver.  However, an increasing number of people are falling victim to low B12 levels– individuals who are unable to absorb vitamin B12 naturally from foods.

People who cannot absorb vitamin B12 are:

  • Individuals who cannot produce intrinsic factor, a protein required for vitamin B12 absorption.
  • Individuals who have had the part of the small intestine responsible for making intrinsic factor removed, as is common procedure in bariatric surgeries (gastric bypass) and gastrointestinal surgeries for Inflammatory Bowel Disease (IBD), such as Crohn’s disease.
  • Anybody who is unable to produce enough stomach acids in order to absorb vitamin B12- these include the elderly, sufferers of gastric autoimmune diseases, diabetes patients who take metformin, and people who take strong antacid medications for acid reflux, such as heartburn (GERD) sufferers or pregnant mothers.


What if I am not tested for vitamin B12 absorption?

Left untreated, vitamin B12 deficiency could result in red blood cell depletion. Other dangerous side effects that stem from being unable to absorb vitamin B12 are elevated risk for heart attack and stroke, neurological damage, and dementia.

If you suspect you might have vitamin B12 deficiency…

  • if you notice symptoms like being tired all the time, talking in slow, unpronounced speech, more difficulty remembering things than normal,
  • if you’ve been diagnosed with comorbid conditions like fibromyalgia, chronic fatigue syndrome, Crohn’s disease, Celiac disease, or hypothyroidism, or
  • if you’ve had weight loss surgery or another types of gastrointestinal procedure…

…then it’s crucial that you request a B12 blood test for vitamin B12 levels, in addition to a Schilling test that measures your ability to absorb B12.

(Gastrointestinal Surgery for Crohn’s (IBD) and B12 Warnings)


The vitamin B12 absorption Schilling test

The Schilling test is more than just a test for B12 levels.  WHAT TEST CHECKS ABSORPTION OF VITAMIN B12? WWW.B12PATCH.COMWhile the standard test for vitamin deficiency checks vitamin B12 levels, the Schilling test determines the reason for your problem with absorption of vitamin B12.

There are four stages of the Schilling test for B12:

  • In stage one, you take two doses of vitamin B12; one is an oral radioactive dose of cobalamin, and the other is a vitamin B12 injection. A urine test determines your absorption of B12
  • In stage two, you take another radioactive dose of vitamin B12- this time, with intrinsic factor.
  • Before going on to stage three, you are required to take antibiotics for two weeks.  Next, a lab technician determines if bacterial growth is the cause of your lack of B12 absorption.
  • Finally, stage four determines if your vitamin B12 deficiency results from a pancreatic disorder.  You will take pancreatic enzymes for a few days, followed by another radioactive dose of vitamin B12.

Read more about vitamin B12 absorption:

Cruising for a Bruising? Choose Vitamin B12 Shots or Anemia

Balance your B12, Balance your Nerves

6 Degrees of Vitamin B12- B12 Deficiency and Autoimmune Disease


Schilling test: MedlinePlus Medical Encyclopedia

Schilling Test- What is a Schilling Test? (PDF)

The Schilling Test & B12- LIVESTRONG.COM

Image credits, from top:

zhouxuan12345678, Genista,  Hey Paul, Horia Varlan