Gastrectomy osteopenia in the rat: the role of vitamin B12 deficiency and the type of reconstruction of the digestive tract

Abstract

1. The mechanisms underlying gastrectomy osteopenia are not yet clear. The gastrectomy-associated cobalamin (vitamin B12) deficiency may favour osteopenia and skeletal fractures. Also, the exclusion of the duodenum from the food passage may contribute to gastrectomy osteopenia. To investigate this, rats were gastrectomized and the passage of nutrients restored either with the duodenum excluded (Roux Y) or included (Longmire). Sham-operated rats served as controls. In half of the rats in each gastrectomy group the serum B12 levels were normalized by parenteral administration of B12.2. Four months post operation, both gastrectomy groups showed a similar degree of osteopenia. There was normal bone mineralization; serum levels of parathyroid hormone were normal, but decreased for 25-hydroxyvitamin D, and elevated for 1,25-dihydroxyvitamin D; in urine there was decreased pH and excessive hyperphosphaturia.3.B12 therapy had no influence on any of the essential bone and mineral metabolic parameters.4. We conclude that osteopenia in the gastrectomized rat (i) is not due to B12 or folic acid deficiency, calcium deficiency or secondary hyperparathyroidism; (ii) is independent of the type of anatomic reconstruction of the digestive tract; (iii) appears to be related to disturbed vitamin D, phosphorus and acid-base metabolism.

Vitamin K₂ Improves Femoral Bone Strength without Altering Bone Mineral Density in Gastrectomized Rats

“…After GX in humans, pigs, and rats, serum gastrin decreases, calcium absorption is impaired, serum calcium and 25(OH) D decrease, and 1,25(OH)2D increases (5,10,(29)(30)(31). GX in rats induces osteopenia (reduced BMC and BMD) (21,25,26,(32)(33)(34).…”

Gastrectomy in the Rat Using Two Modifications of Esophagojejunal Anastomosis

“…The serum levels of free fatty acids and ·-amino nitrogen were normal in all rats. Microcytic anemia developed in GX rats, an observation that has previously been made [9,13]. The hematocrit was lower in the GXR groups than in the GXL groups, anemia was most severe in GXR-S rats.…”

“…Based on the adjusted correlation coef- ficient in each of the two models, the influential variables studied explained about 63 and 56% of the variation in bone density and hematocrit, respectively. Additional factors must therefore contribute to low post-GX bone density and hematocrit [5,13]. Evidently, food intake is only a weak indicator of the mineral metabolic and the hematopoietic state of bone.…”

“…For clinical chemistry determinations, routine procedures were used, several of which have been described previously, including the radioimmunoassays of gastrin and rat osteocalcin [5,13].…”

“…Removal of the stomach is frequently followed by long-term metabolic disturbances such as anemia [9,13] and osteopenia [1, 3-5, 7, 8, 13]. Chronic inflammation has been reported to induce anemia in man [14] and osteopenia in the rat [15][16][17].…”