No items found.
X Fact
July 7, 2021
2 Minute Read
Complexity Rating

uMMA - 'Catch-22' or Catch-all?

The main reason doctors don't order a uMMA (urinary MMA) test for B12 deficiency is because they don't know about it and it is not performed by most clinical laboratories. One could also say that it is not widely available, because doctors don't ask for it - a proverbial 'Catch-22'. This is a pity, because the test has been shown to be especially useful when the B12 blood level test falls in the low-normal range.

For decades, the threshold for diagnosing deficiency from a blood B12 test was 200 ng/L (148 pmol/L). In a recently published study, 490 hospital patients were tested for vitamin B12 status and nearly 30% were found to have a blood B12 level between 201-350 ng/L - i.e. on the low end of a very wide range of what is considered normal (200 - 950 ng/L). If the blood B12 level was used as the sole determinant of their B12 status, the test would be reported as normal. But when taking into account blood MMA and homocysteine levels, 69 out of the 127 with low-normal levels were found to be B12 deficient.

In other words, over half (54.3%) of the patients who would be told they have a normal result on their blood B12 test alone, WERE in fact B12 deficient. The uMMA test confirmed the results and is more accurate than blood MMA or homocysteine levels when individuals have even very slight decrease in kidney function - which is quite common. Is uMMA a 'Catch-All' test for B12 deficiency? No, but it is very useful when the diagnosis is in doubt or when B12 blood levels are in the low-normal range.

Words You May Not Know
Quick View


Methylmalonic acid (MMA) is a compound that reacts with vitamin B-12 to produce coenzyme A (CoA). Coenzyme A is essential to normal cellular function. When vitamin B-12 deficiencies occur, methylmalonic acid levels increase.

Quick View


A creatinine test is a measure of how well your kidneys are performing their job of filtering waste from your blood. Creatinine is a chemical compound left over from energy-producing processes in your muscles. Healthy kidneys filter creatinine out of the blood. Creatinine exits your body as a waste product in urine. A measurement of creatinine in your blood or urine provides clues to help your doctor determine how well the kidneys are working.

Who Wrote This X Fact
Jonathan Bortz MD
Bio Quick View

Jonathan’s background as a practicing diabetes specialist for 15 years and 17-year career developing nutritional prescriptive products for the pharmaceutical industry has contributed to his ability to understand nutrients, how they work and why they are important.

Over the years he has acquired broad and in-depth knowledge in minerals, essential fatty acids and other nutrients, but has special expertise in Vitamin B12 and choline metabolism. He is often asked to speak at national and international venues to articulate why B12, folate and choline are so important to gene function, brain development, liver and cardiovascular health. He applies pharmaceutical standards to nutrient science and has developed a unique ability to translate complicated concepts into simple promotional messages that resonate with practitioners and consumers. He has developed dozens of innovative nutritional products, of which many are category leaders in the US. Jonathan obtained his medical degree from the University of the Witwatersrand Medical School in South Africa and did his fellowship in Endocrinology at Washington University in St. Louis, MO.

Top Picks
Recent X Facts