Endocrine Abstracts

Introduction: The biochemical diagnosis of acromegaly is based on elevated plasma growth hormone (GH) that fail to suppress after an oral glucose load. Elevated insulin like growth factor 1 (IGF1) supports the diagnosis. Traditionally GH level of less than 2 miliunits per litre rules out acromegaly. With advent of recent sensitive GH assays, lower levels of GH are increasingly being recognized. We describe a case of acromegaly which differed from the traditional presentation.

Case Report : 52 year old male had migraine like headaches associated with visual disturbances in the form of difficulty in focusing. These episodes happened thrice. He denied having excessive perspirations, increase in hands and feet, change of facial features, hyperosmolar or cardiac symptoms or entrapment neuropathy signs. Basal Metabolic Index 33 ( all his siblings were 'big'), blood pressure 150/80 milimetre of mercury. No macroglossia, skin tags or entrapment neuropathy signs. Facial appearance normal and proportionate hands and feet. Visual fields were full on confrontation. Routine haematology and biochemistry normal. Prolactin, gonadotrophins, testosterone and thyroid function tests were normal. IGF1 raised at 51.4 nanomol per litre and GH suppressed to l miliunit per litre on oral glucose tolerance test (OGTT). Magnetic resonance imaging (MRI) of pituitary gland showed 8milimetre diameter tumour. Cabergoline was started and three months later IGF1 was still high and tumour size did not change on MRI. GH day profile was in the range of 1.6 to 4.9 miliunits per litre. Transphenoidal adenomectomy was done in September. Post operative IGF1 30.7 nanomol per litre. Further post operative dynamic pituitary function tests awaited.

Conclusion: Highly sensitive growth hormone assays will have a significant impact on our recognition of acromegaly. GH criteria for interpretation of OGTT for diagnosis and follow up of acromegaly need to be refined. IGF1 must be measured to support the diagnosis.