Vitamin B12 monitoring — what worked for you?

bri_stats said:

I started taking a multivitamin as insurance and then found out that two of the things I was actually short of were the two it barely contains.

Blood count monitoring for micronutrients: my doctor noticed my MCV (mean corpuscular volume) trending up at month 6: 89 → 98 fL. This flagged potential B12 or folate deficiency.

Sure enough, B12 had dropped from 620 to 340 pg/mL. Started B12 injections monthly and MCV normalized within 2 months. GLP-1 agonists can impair B12 absorption — this is a real clinical concern that deserves routine monitoring.

BethLabQueen said:

Blood count monitoring for micronutrients: my doctor noticed my MCV (mean corpuscular volume) trending up at month 6: 89 → 98 fL.

Vitamin and mineral labs to check while on micronutrients — my doctor orders these quarterly:

• B12: Can drop due to reduced GI absorption. Mine went from 650 to 380 — now supplementing.
• Iron/Ferritin: Reduced food intake = reduced iron. Ferritin dropped from 56 to 23. Supplementing.
• Vitamin D: Was already low (23 ng/mL), now taking 5000 IU daily.
• Folate: Stable, no issues.
• Zinc: Slightly low, added a multivitamin with zinc.

Nutritional deficiencies are a real risk when you're eating significantly less. Don't skip your labs!

bri_stats said:

I started taking a multivitamin as insurance and then found out that two of the things I was actually short of were the two it barely contains.

Same pattern here, and in the same order. I had assumed I was the exception until I read this.

Clinical perspective, offered as context rather than as advice.

Iron studies on micronutrients — important especially for women:

My ferritin cratered at month 6 from reduced dietary intake. Iron bisglycinate 36mg with vitamin C brought it back up. Don't wait for anemia symptoms — test proactively.