Resistance to a long-acting somatostatin analog (SMS 201-995) reversed by surgery in acromegaly.
A 42-year-old woman had acromegaly and a large macroadenoma with supra- and parasellar extension. Her GH levels (median 85 ng/ml, range 63-170 ng/ml) were not responsive to TRH (200 micrograms iv), GHRH (100 micrograms iv) and bromocriptine (Br 2.5 mg po) acute tests; Sm-C level was 8 U/ml. She was treated with octreotide (SMS) (up to 1500 micrograms daily) for 3 months. No changes of clinical, biochemical and radiological findings were seen, therefore she underwent transsphenoidal surgery. After surgery, hypopituitarism and diabetes insipidus appeared: GH levels remained high (median 45 ng/ml; range 37-56 ng/ml), but became responsive to Br acute test. The patient was given SMS again, and this resulted in clinical improvement, marked reduction of GH and Sm-C levels and slight shrinkage of the residual tumor. Speculative hypotheses about this previously unreported phenomenon might be either an excess of both GHRH and somatostatin, caused by a primary increase of dopaminergic tone, or a primary excess only of GHRH; in both cases the surgical lesion of the hypothalamic-pituitary region might have impaired the neurohormones inflow to the residual pituitary and so let SMS and Br exert their inhibitory actions on GH secretion.
Attanasio
R
R
Divisione di Endocrinologia, Ospedale Niguarda, Milano, Italy.
Chiodini
P G
PG
Liuzzi
A
A
Orlandi
P
P
De Palo
C
C
Dallabonzana
D
D
Lodrini
A
A
Cozzi
R
R
D000172:Acromegaly / Q000188:drug therapy / Q000601:surgery / Q000628:therapy*; D000236:Adenoma / Q000150:complications / Q000601:surgery; D000328:Adult; D004351:Drug Resistance; D005260:Female; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D015282:Octreotide / Q000627:therapeutic use*; D010911:Pituitary Neoplasms / Q000150:complications / Q000601:surgery; D011388:Prolactin / Q000097:blood; D011863:Radioimmunoassay; D014057:Tomography, X-Ray Computed
D011388:Prolactin; D013006:Growth Hormone; D015282:Octreotide