Acromegaly

Regarding a person with acromegaly presenting for transsphenoidal hypophysectomy, which of the following statements is MOST LIKELY to be true?

a) The patient is more likely to be male than female

b) Males with acromegaly are as likely to suffer fromobstructive sleep apnoea as females

c) Patients with acromegaly are more likely to have a distal rather than a proximal myopathy

d) They are likely to have raised adrenocorticotrophic hormone (ACTH) levels

e) They are likely to have raised levels of insulin-like growth factor-1 (IGF-1)

Answer: e

Explanation

Patients with acromegaly can present in a number of ways, but as an anaesthetist one is most likely to encounter them just prior to pituitary surgery as over 90% are secondary to a benign growth hormone (GH) secreting tumour. Of these tumours, 25% also secrete prolactin. The remaining 10% of cases are secondary to either ectopic GH production or due to excess growth hormone-releasing hormone (GHRH). This may be from either a hypothalamic tumour or ectopic GHRH production by tumours of the pancreas, kidneys or lungs. Growth hormone induces the synthesis of peripheral IGF-1, which acts by inducing cell proliferation and reducing apoptosis hence, over time, leading to the characteristic features associated with the condition. Due to local destruction of the anterior pituitary gland by the tumour, production of other pituitary hormones (e.g. adrenocorticotropic hormone and thyroid stimulating hormone) may be reduced. Diagnosis ismade by initial measurement of IGF-1 levels and if this is abnormal proceeding to measurement of GH levels during a standard glucose tolerance test and if this is abnormal, pituitary imaging by MRI scan. Anaesthetic implications of this condition are multiple but include raised intracranial pressure, cardiovascular disease (the most frequent cause of death in untreated acromegaly with up to 50% of patients dying before the age of 50), potential for difficult intubation, obstructive sleep apnoea (more common in males than females) and a proximal myopathy.

Reference

Melmed S. Medical progress: acromegaly. New Engl J Med 2006; 355(24): 2558–73.