A recent case study (L Jimenez et al. J Pediatr 2018; 192: 259-61) showed that methylamalonic acid (MMA) can be elevated in the absence of vitamin B12 deficiency.

Background:

• Risk factors for vitamin B12 deficiency: terminal ileal resection and gastric acid blockade
• Manifestations of vitamin B12 deficiency: megaloblastic anemia, bone marrow failure, demyelinating diseases, thrombosis, and psychiatric symptoms
• Early assessment of vitamin B12 deficiency can be aided by MMA levels and homocysteine levels both of which are metabolized via vitamin B12-dependent pathways and are elevated in vitamin B12 deficiency.
• MMA levels have higher sensitivity for vitamin B12 deficiency than vitamin B12 levels alone.

Key findings of this report:

• In three children with short bowel syndrome, MMA levels were persistently elevated despite vitamin B12 supplementation and without other evidence of vitamin B12 deficiency
• MMA levels declined after treatment of bacterial overgrowth
• “It is hypothesized that propionate, a precursor to MMA, produced by excessive gut fermentation, is responsible for the elevation in plasma MMA levels.”

My take: this study is a good reminder of how MMA is useful in detecting vitamin B12 deficiency and points out that bacterial overgrowth may be an alternative explanation for elevated MMA levels.

Related blog posts:

• What I didn’t know about Vitamin B12 deficiency and Crohn’s disease (consider Vitamin B12 deficiency if ileal resection >20-30 cm)
• Risk of Vitamin B12 Deficiency with Persistent PPI Usage
• Are we missing Vitamin B12? | gutsandgrowth
• N2U -Part 2: Poor Growth and Short Bowel Syndrome | gutsandgrowth

Resources for Short Bowel Syndrome:

• http://www.oley.org
• http://www.shortbowelfoundation.org
• http://www.shortbowelsyndrome.com/sign-up.  This website, sponsored by Shire, has a patient’s guidebook available: Parrish, CR. A Patient’s Guide to Managing a Short Bowel, 4th Edition; June 2016; 1-66.

Disclaimer: These blog posts are for educational purposes only. Specific dosing of medications/diets (along with potential adverse effects) should be confirmed by prescribing physician/nutritionist.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

Bright Angel Trail, Grand Canyon