Circulating immunoreactive somatostatin in man. Effect of age, pregnancy, growth hormone deficiency and achlorhydria

Abstract

Abstract. Plasma immunoreactive somatostatin (IRS) levels were measured fasting at 09.00 h in groups of adult individuals and children of different ages, as well as in pregnant women, in patients with pernicious anaemia documented to be achlorhydric, and in children with growth hormone deficiency. There was a gradual rise in the mean level of IRS from the third decade (mean 35.8 ± 3.8 pg/ml), which reached significance at the seventh (61.1 ± 8.4 pg/ml), eighth (66.7 ± 5 pg/ml) and ninth decade (82.6 ± 13.8 pg/ml). No change was observed in the second 28.3 ± 3.8 pg/ml) and third (31.1 ± 3.2 pg/ml) trimester of pregnancy when compared with matched, non-pregnant controls (29.7 ± 2.2 pg/ml); however, the children aged under 2 years (69.6 ± 11.2 pg/ml) had significantly higher values than the eldest group (12 to 16 years old) (46.3 ± 7.2 pg/ml) (P < 0.05). In achlorhydric patients, basal (27.2 ± 3.7 pg/ml; P < 0.01) and postprandial IRS (42.8 ± 7.7 pg/ml; P < 0.001) was significantly lower than in a matched, normal control group (basal 59.4 ± 7.2; postprandial 132.1 ± 26.3 pg/ml). Growth hormone deficiency was not associated with any differences in circulating IRS, basally or after insulin hypoglycaemia, when compared with values in normal children. These results would suggest, 1) that age has a significant effect on plasma IRS, and should be considered in the interpretation of fasting plasma levels of IRS; 2) that pregnancy and growth hormone deficiency is not accompanied by any changes in circulating IRS and presumably, somatostatin binding proteins; 3) that gastric acid is necessary for a normal release of IRS from the gastrointestinal tract to the circulation.