Abstract and Introduction
Disease activity of acromegaly can be measured in many ways. Growth hormone (GH) and insulin-like growth factor 1 (IGF1) concentrations are the main biochemical markers used to measure the response to treatment. Both GH and IGF1 have been associated with prognosis, in particular mortality. In this review, we discuss the available parameters to assess disease activity in acromegaly.
Acromegaly is a rare disease that is most often caused by a growth hormone (GH) secreting benign pituitary tumour. The autonomous increased production of GH results in increased insulin-like growth factor 1 (IGF1) concentration and both cause signs and symptoms. This disease is characterized by soft tissue enlargement and excessive skeletal growth with characteristic acral enlargement and coarse facial features. Complications related to excessive secretion of GH and IGF1 include cardiomyopathy and sleep apnoea syndrome, and result in a two- to threefold increase in mortality if left untreated.
Growth hormone and IGF1 are the "classical" biochemical parameters used to diagnose acromegaly and to assess disease activity during treatment. Several studies have related control of acromegaly, defined by a normal IGF1 and/or a certain GH concentration, to an improved mortality risk and to prevalence of several co-morbidities.[2–10] However, in the near normal range, both biochemical markers have limited ability to discriminate active and adequately controlled acromegaly, because of broad normal ranges, assay limitations and individual factors. Therefore, GH and IGF1 levels may not always adequately reflect disease activity as measured by acromegaly symptoms, while patients may well be subjected to ongoing GH and IGF1 excess, and GH-induced tissue damage. Quality of life (QoL), assessed by questionnaire, is a measure of a patient's perception of their general health, and an important goal to aim for in the treatment of chronic diseases. QoL can be used as a biomarker to study disease control in acromegaly in certain circumstances.
In the later section, we will discuss the parameters of disease activity, GH, IGF1 and QoL. Although they will change concordantly in the majority of patients with treatment, in some patients clinical and biochemical markers may dissociate. In this review, we will discuss the relevance and limitations of different disease parameters.
Clin Endocrinol. 2012;76(5):609-614. © 2012 Blackwell Publishing