PARATHORMONE LEVELS DURING TREATMENT OF ACROMEGALY WITH OCTREOTIDE - ONE-YEAR FOLLOW-UP

Serum growth hormone (GH), insulin-like growth factor I (IGF-I), calci um, phosphate, osteocalcin, and intact parathormone (PTH) were measure d in 10 patients with active acromegaly before and after 1, 6, and 12 months of treatment with octreotide (50 to 100 mug subcutaneously TID) . Serum GH and IGF-I decreased after 1 month, and this effect was main tained at 6 and 12 months. A transient decrease in calcium and a persi stent decrease in osteocalcin were also seen. Before treatment, calciu m, phosphate, and osteocalcin levels were higher in the patients with acromegaly than in the 25 healthy controls; at 12 months, only the pho sphate levels remained higher than baseline in the acromegalic patient s. The levels of PTH were comparable in both groups before treatment, but were elevated in the patients with acromegaly after treatment. The lower calcium and osteocalcin levels recorded during octreotide treat ment are similar to those seen after pituitary adenomectomy, but the p hosphate and PTH values suggest that octreotide exerts further actions on calcium homeostasis. In addition to the reduced 1,25-dihydroxyvita min D synthesis caused by the lowered GH levels, octreotide might caus e intestinal malabsorption of calcium, which consequently stimulates P TH secretion.