A 45-year-old man undergoes total gastrectomy for gastric carcinoma. Which of the following nutritional/physiological deficiencies will develop EARLIEST, requiring immediate supplementation?
- A Vitamin B12 deficiency — loss of intrinsic factor prevents ileal absorption; however, body stores last 3–5 years
- B Calcium malabsorption — requires gastric acid for solubilization before duodenal absorption
- C Iron deficiency anemia — requires acidic gastric environment for reduction to ferrous form and is absorbed in proximal duodenum ✓
- D Fat-soluble vitamin deficiency — loss of pancreatic stimulation reduces bile acid secretion and fat digestion
Explanation
After total gastrectomy: (1) Iron deficiency is the EARLIEST deficiency because gastric acid converts dietary Fe3+ (ferric) to Fe2+ (ferrous) for absorption, and gastric acid is completely absent. Iron stores are modest (3–4 weeks of erythropoiesis), so deficiency develops within months. (2) Vitamin B12 deficiency (megaloblastic anemia) develops slowly over 3–5 years because hepatic stores are large and the enterohepatic circulation partially compensates before intrinsic factor dependence becomes critical. (3) Calcium absorption is also impaired but less acutely critical. Iron deficiency anemia is the earliest clinical problem post-gastrectomy.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
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