Acromegaly: unravelling a complex disease.

Acromegaly is a rare endocrine disorder characterized by growth hormone hypersecretion and is usually caused by a pituitary macroadenoma. It is associated with significantly increased patient morbidity and mortality. Molecular biological studies have implicated a causative role for oncogenic mutations (activating Gs alpha mutations and/or chromosomal 11q13 deletions) in less than 50% of cases. The cause(s) in the remaining 50% is speculative. Epidemiological evidence indicates that biochemical cure is achieved when mean GH levels are 5mU/l or less during a day-profile. This GH value correlates well with that required to normalize the serum IGF-1 concentration, a GH-dependent peptide which can be used to monitor the disease activity in acromegaly. Treatment must be carried out under the supervision of a dedicated endocrinologist and tailored to patients needs. The success of any treatment modality (surgery/pituitary irradiation/medical) depends on adenoma size and the extent of pretreatment GH hypersecretion. A combination of therapies is usually required to achieve satisfactory control of adenoma growth and GH hypersecretion. Octreotide, a synthetic analogue of native somatostatin, is particularly effective in controlling GH hypersecretion in this condition and the widespread introduction of a long-acting depot preparation is eagerly awaited. The development of true GH deficiency as a result of treatment is potentially worrying in view of its possible contribution to the increased incidence of cardiovascular mortality associated with hypopituitarism.