Intramuscular Cyanocobalamin Treatment in Patients with Corpus Atrophic Gastritis and Vitamin B12 Deficiency: Efficacy and Predictors of Increased Requirement-A Monocentric Longitudinal Real-Life Cohort Study.
Nearly 70% of CAG patients with vitamin B12 deficiency restored their vitamin B12 levels with 20,000 µg/yr of intramuscular cyanocobalamin, while the remaining 30% required 30,000 µg/yr, with switching to higher dosage significantly associated with severe corpus intestinal metaplasia, macrocytosis at diagnosis, and male sex.
Key Findings
Results
The first treatment schedule (TxA, 20,000 µg/yr) efficaciously corrected vitamin B12 deficiency in 68.5% of CAG patients with vitamin B12 deficiency.
146 of 213 CAG patients (68.5%) achieved vitamin B12 normalization with TxA.
TxA consisted of 5000 µg IM cyanocobalamin every 5 days for 3 times, followed by 5000 µg IM cyanocobalamin every 3 months (20,000 µg/yr).
Efficacy was maintained until the longest available follow-up of 42.2 ± 2.6 months.
The treatment endpoint was defined as serum vitamin B12 normalization (≥220 pg/mL).
Results
31.5% of CAG patients required switching to the second treatment schedule (TxB, 30,000 µg/yr) due to persistent vitamin B12 deficiency.
67 of 213 patients (31.5%) were switched to TxB due to persistent vitamin B12 deficiency observed at 12 (6–36) months.
TxB consisted of 5000 µg IM cyanocobalamin every 5 days for 3 times, followed by 5000 µg IM cyanocobalamin every 2 months (30,000 µg/yr).
TxB was maintained until the longest available follow-up of 50.2 ± 4.1 months.
Clinical-biochemical follow-up was scheduled every 12 ± 6 months.
Results
Both treatment schedules significantly increased hemoglobin levels at the longest available follow-up.
TxA: Hb increased from 11.9 ± 0.2 to 13.1 ± 0.1 g/dL (p < 0.001).
TxB: Hb increased from 12.2 ± 0.3 to 13.6 ± 0.2 g/dL (p = 0.003).
At baseline, 48.3% of the 213 CAG patients had anemia and 26.3% had macrocytosis without anemia.
Results
Both treatment schedules significantly increased serum vitamin B12 levels at the longest available follow-up.
TxA: serum vitamin B12 increased from 168 ± 7 to 402 ± 19 pg/mL (p < 0.0001).
TxB: serum vitamin B12 increased from 157 ± 12 to 340 ± 24 pg/mL (p < 0.0001).
Inclusion criteria required vitamin B12 deficiency defined as serum vitamin B12 < 220 pg/mL.
Results
A significant decrease in mean corpuscular volume (MCV) was observed in TxB patients only.
A significant decrease in MCV was shown in TxB only (p = 0.0003).
No significant decrease in MCV was reported for TxA patients.
26.3% of patients had macrocytosis without anemia at baseline.
Results
Switching to the higher-dose treatment schedule (TxB) was significantly associated with three independent predictors in logistic regression analysis.
Severe corpus intestinal metaplasia was the strongest predictor (OR 11.0, 95% CI 2.8–43.7).
Macrocytosis at CAG diagnosis was also a significant predictor (OR 2.7, 95% CI 1.2–6.3).
Male sex was independently associated with requiring TxB (OR 2.4, 95% CI 1.1–5.2).
Methods
The study cohort of 213 CAG patients with vitamin B12 deficiency had a high prevalence of hematological manifestations at baseline.
48.3% of patients had anemia at baseline.
26.3% had macrocytosis without anemia at baseline.
Inclusion criteria required adult age, histological diagnosis of CAG, vitamin B12 < 220 pg/mL, and follow-up of more than 12 months.
This was a monocentric real-life cohort study with longitudinal follow-up.
Schiavone F, Pivetta G, Scalamonti S, Pompili M, Magnante M, Esposito G, et al.. (2026). Intramuscular Cyanocobalamin Treatment in Patients with Corpus Atrophic Gastritis and Vitamin B12 Deficiency: Efficacy and Predictors of Increased Requirement-A Monocentric Longitudinal Real-Life Cohort Study.. Nutrients. https://doi.org/10.3390/nu18020271