To investigate the effects of gastrectomy on calcium metabolism, we studied fractional calcium absorption and urinary excretion, as well as changes of ionized calcium and hormones related to calcium metabolism between the pre- and 30 days
post-operative
periods after subtotal gastrectomy in 7 male patients with stomach carcinoma.
The preoperative mean height was 168±5cm, the preoperative mean weight was 57±5kg, and the mean loss of weight was 5kg. Daily calcium intake in the postoperative period was decreased by 24% compared to the preoperative period(652±203mg/d) and
intakes
of calorie, carbohydrate, protein and fat were also decreased by 40-50%. Serum biochemical tests related to calcium metabolism and the ratios of calcium and phosphorus to creatinine in 24-hour urine were not different between two periods.
Fractional calcium absorption test using 45Ca showed delayed peak serum level at 2 hour in the postoperative period while at 1 hour in the preoperative period. However, areas under the curve for 3 hours were not different between two periods. At
the
same time, urinary excretion of 45Ca for 3 hours were also not different.
The preprandial level of gastrin(49.00±42.71 vs. 17.52±11.58pg/ml) was decreased but those of ionized calcium(4.1±0.5vs. 4.4±0.7mg/dl), parathyroid hormone(21.64±5.18 vs. 23.94±5.05pg/ml), calcitonin(45.35±7.49 vs, 47.13±15.97 pg/ml), and
especially vitamin D metabolites of 25(OH)D (16.57±6.39 vs. 12.92±2.6ng/ml) and 1,25(OH)2D(131.7±66.38 vs. 181.57±24.51pg/ml) were not changed after gastrectomy. The postprandial changing patterns of ionized calcium, calcitonin and
parathyroid
hormone were also not different except for absent reponse of gastrin.
In summary, calcium intake was decreased was decreased in spite of encouraged high calcium diet but both fractional calcium absorption and urinary excretion were not changed after gastrectomy. There was also no change in the postprandial patterns
of
ionized calcium, parathyroid hormone and calcitonin except for absent response of gastrin in postoperative period as well as in the fasting levels of vitamin D metabolites such as 25(OH)D and 1,25(OH)2D.
It may be concluded that calcium balance is not maintained due to inadequate oral calcium intake rather than poor calcium absortion in 30 days after subtotal gastrectomy. We need longterm follow-up study and also comparative study between total
and
subtotal gastrectomy to clarify the effects of gastrectomy on calcium metabolism.
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