Checking for a Vitamin B12 Deficiency: the Urine Test
Often, checks for a vitamin B12 deficiency are carried out by determining the concentration of vitamin B12 in blood serum. However, this value isn’t actually all that significant, since the test also measures the vitamin B12 which the body cannot use. Unfortunately, a clinical deficiency within the cells can be present even when vitamin B12 levels show up as normal in the blood.
A more worthwhile way of testing is to measure either the bioavailable vitamin B12 alone (HoloTC test) or the concentration of various metabolic products which change with the occurrence of a cellular vitamin B12 deficiency; namely the concentrations of homocysteine and methylmalonic acid (MMA).
Methylmalonic Acid – Clear Indication of a B12 Deficiency
During a vitamin B12 deficiency, the concentration of methylmalonic acid rises both in the blood and in the urine. Since there is only one, vitamin B12 dependent metabolic pathway for conversion of MMA, the methylmalonic acid urine test is a reliable indicator as to whether a functional vitamin B12 deficiency is present or not. A distortion in results is only clinically possible with certain rare hereditary diseases, serious nutritional deficiencies and a rare bacterial overgrowth in the intestinal tract.
As a result of this, the MMA urine test is seen as the most reliable method, alongside the the HoloTC test, for determining a vitamin B12 deficiency.
Vitamin B12 Deficiency Urine Test: Method and Cost
Carrying out a urine test is just as easy as you’d imagine. A urine sample from the morning is all that is required for the test. This is then sent to a corresponding lab and tested there. Unfortunately, it is not possible to carry out a self-examination with a medical dipstick or similar.
Analysis of a Vitamin B12 Urine Test
Analyzing the test is just as simple as taking it. The concentration of MMA is measured in comparison with the concentration of creatine, to account for variation in the excretion capacity of the kidneys.
up to 3.6 mmol MMA/mol creatine
up to 2 mg MMA/g creatine
No vitamin B12 deficiency
over 3.6 mmol MMA/mol creatine
over 2 mg MMA/g creatine
Vitamin B12 deficiency
Interpretation of Test Values and Treatment Guidelines
After receiving the individual test results, the question naturally arises as to how to view them and above all what to do next. Unfortunately, the boundary for a deficiency is set by each laboratory individual, as do the units for measurement used. Most give a value in mg of vitamin B12 per g of creatine. Current boundaries for deficiency stand at 2 mg/g creatine and 2.6 mg/g creatine.
We are of the opinion that a deficiency can be expected even at a value of 2 mg/g, so subsequently this is the limit that we take. The following table shows a possible interpretation of the results of a urine test and gives suitable treatment guidelines.
Recommendations for supplements
|clearly under the limit|
< 1.5 mg/g
No B12 deficiency
roughly around the limit
B12 deficiency possible
It is recommended to take a low dosage supplement to defend against any minor symptoms
5 – 10 µg oral/day
|Clearly over the limit|
> 2.5 mg/g
|Begin taking supplements. Seek the cause of the deficiency.|
250 – 500 µg oral/day
> 5 mg/g
Severe B12 deficiency
Begin taking supplements. Seek the cause of the deficiency.
A consultation with a therapist is often worthwhile.
Consider taking a blood test for HoloTC and homocysteine with a doctor, to verify the result.
|500 µg oral/day|
1000 µg/week intramuscular for 4 Weeks
Who Should Take a Vitamin B12 Deficiency Test?
The elderly, Vegetarier und Veganer should check their vitamin B12 levels regularly, as these are the most common sufferers of a deficiency. Additionally, testing is highly recommended for anyone who shows several symptoms of a vitamin B12 deficiency. In particular, patients with anemia, dementia, multiple sclerosis, fibromyalgia and chronic fatigue syndrome should certainly check their vitamin B12 status, since a vitamin B12 deficiency may be worsening the symptoms here.
Most doctors and naturopaths recommend first carrying out a test, before beginning to take vitamin B12 supplements.
What can be done if a Vitamin B12 Deficiency is Present?
If the test reveals a vitamin B12 deficiency, it is recommended to begin taking vitamin B12 supplements. At the same time, it is important to begin looking into what caused the vitamin B12 deficiency. If the diet isn’t the cause, then it is probable that an absorption problem exists, which should be explored further. In the majority of cases, stomach and intestinal tract diseases play a decisive role here. These are explored further in our article on the causes of a vitamin B12 deficiency.
When taking supplements, it’s important to choose a generous dose in order to replenish the body’s B12 store, which is likely to be very low. After this, it is usually recommended to transfer over to a lower, maintenance dose, to cover the body’s daily requirement. More information on the choice and dosages of vitamin B12 supplements can be found in the corresponding article.