Treatment of acromegaly with somatostatin analogs (SA) is well-established and are primarily used after insufficient surgical intervention, but also as primary medical treatment in selected patients. Evaluation of treatment control is based on monitoring blood levels of growth hormone (GH) and insulin-like growth factor-I (IGF-I). However, evaluation of disease control during SA treatment is not always straightforward. It is usually based on normalization of IGF-I and achievement of a certain GH level. In approximately 40% of patients discordant values of GH and IGF-I levels are seen after treatment with SA, with normalized IGF-I levels, despite elevated GH levels. The mechanism behind this observation is unknown, but it indicates that SA may affect this difference.

The primary objective of this study is to investigate if disease control during SA treatment is best achieved by monitoring either GH or IGF-I.

Inclusion Criteria:

• Written informed consent
• Age > 18 years
• Capable and of age
• Diagnosed with acromegaly
• Sufficient treated for at least 6 months prior to enrollment

Exclusion Criteria:

• Pregnancy or nursing
• Any disease that may compromise the ability to comply with the protocol, as assessed by the investigator