From the Guidelines
After partial gastrectomy, the main reason for anemia is decreased absorption of iron, not increased intrinsic factor or increased absorption of iron. When part of the stomach is removed, there is reduced production of acid that helps convert dietary iron to its absorbable form, so less stomach means less acid production and consequently reduced iron absorption. The altered anatomy can lead to more rapid transit of food, giving less time for nutrient absorption. These deficiencies commonly manifest as either iron deficiency anemia. Patients who have undergone partial gastrectomy typically require regular monitoring of their blood counts and may need supplementation with oral iron to prevent or treat anemia, as stated in the guidelines for the management of iron deficiency anaemia 1. Key factors contributing to iron deficiency anemia after partial gastrectomy include:
- Reduced acid production in the stomach, which is essential for converting dietary iron into its absorbable form 1
- Altered anatomy leading to rapid transit of food and reduced time for nutrient absorption
- Potential for chronic blood loss, although this is more commonly associated with bariatric surgery procedures like Roux-en-Y gastric bypass 1 It's also worth noting that while bariatric surgery can lead to iron deficiency, the mechanisms and treatments may differ from those after partial gastrectomy, with intravenous iron being a preferred treatment option in some cases 1. However, the primary concern after partial gastrectomy remains the decreased absorption of iron due to reduced acid production and altered anatomy.
From the Research
Main Reason for Anemia after Partial Gastrectomy
The main reason for anemia after partial gastrectomy is due to deficiencies in essential nutrients, particularly:
- Iron deficiency anemia, which was present in 94.4% of gastrectomized patients with anemia 2
- Vitamin B12 deficiency, which was present in 79.2% of gastrectomized patients with anemia 2
Causes of Deficiencies
The causes of these deficiencies include:
- Reduced absorption of iron and vitamin B12 due to the removal of parts of the stomach, which produces gastric acid and intrinsic factor necessary for their absorption 3, 4
- Malabsorption of vitamin B12, which can occur years after gastrectomy due to the depletion of hepatic storage 3
Key Findings
Key findings from the studies include:
- The combination of iron and vitamin B12 deficiencies is the most common cause of anemia in gastrectomized patients 2
- Vitamin B12 deficiency can develop as early as 1 year after total gastrectomy and causes symptoms, which can be treated with enteral B12 supplements 4
- The prevalence of vitamin B12 deficiency is high in patients early after and before gastrectomy, and coexists with iron deficiency anemia 3
Risk Factors
Risk factors for vitamin B12 deficiency after gastrectomy include:
- Type of gastrectomy, with total gastrectomy having a higher risk than distal subtotal gastrectomy 5
- Preoperative vitamin B12 level, with lower levels increasing the risk of deficiency 5
- Age, with elderly patients being more likely to experience vitamin B12 deficiency after distal subtotal gastrectomy 5