Fasting serum gastrin in primary hyperparathyroidism and in chronic hypercalcemia

In order to investigate the frequency of fasting hypergastrinaemia in primary hyperparathyroidism (A) and in chronic hypercalcaemia (B), in 40 and 16 patients respectively gastrin, parathyroid hormone (PTH) and serum calcium levels were measured and compared with those of a control group (40 subjects) with similar distribution of sex and age. Moreover, possible linear relationships between these parameters were investigated. Notwithstanding significant differences in calcium and PTH levels between the three groups (A: high PTH, high Ca++; B: low PTH, high Ca++; C: normal PTH and Ca++ levels), no significant difference in gastrin levels were found. However, in the first group, a marked increase of gastrin was observed in one patient, very probably affected by a gastrin-secreting tumor (positive secretin test). While no linear relationship between PTH and gastrin values was present in all the three groups, a significant correlation between serum calcium and fasting gastrin was detectable in the group A, ruling-out the above mentioned patient. Present data suggest that PTH does not modify gastrin levels and that chronic moderate hypercalcaemia does not raise serum fasting gastrin, at least in clinical conditions. Moreover, the frequency of hypergastrinaemia in hyperparathyroidism is very low and it seems to be present only in patients with gastrin-secreting tumors.