Therapy of acromegaly with sandostatin: the predictive value of an acute test, the value of serum somatomedin-C measurements in dose adjustment and the definition of a biochemical 'cure'.

Fifteen acromegalic patient were treated for a mean of 96 weeks with 200-300 micrograms Sandostatin per day. The mean 24 h GH concentration decreased by 86% from 34.3 +/- 6.6 to 4.8 +/- 0.7 micrograms/l (1 microgram/l = 46 pmol/l). There was a close correlation between the mean GH levels from 2 to 6 h after the acute administration of 50 micrograms Sandostatin and the mean 24 h GH levels after chronic therapy (P less than 0.01). Serum Sm-C levels decreased from 6.9 +/- 0.7 to 2.7 +/- 0.5 U/ml (-61%) and normalized in eight of these 15 patients. There was a close correlation between the Sm-C and mean 24 h GH levels after therapy (P less than 0.001). It is suggested that adjustment of the dose and the number of Sandostatin injections can be made in acromegaly on the basis of the measurement of Sm-C levels during the follow-up. This precludes the need of multiple GH determinations throughout the day and/or night. Biochemical 'cure' (as defined by normalized Sm-C levels) was reached in eight patients in whom mean 24 h GH levels were suppressed to 3.3 micrograms/l or less. The normalization of Sm-C levels was even observed in the presence of two or three GH secretory peaks (never exceeding 7.5-10 micrograms/l) during the 24 h period occurring towards the next Sandostatin injection.