This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of pituitary gland, Subject name: Medicine
Which of the following is the leading cause of GHRH mediated acromegaly? 
Select and explain. 
A. Hypothalamic Hamaoma, B. Choristoma, C. Carcinoid tumour, D. Pluri-hormonal adenoma
C: Carcinoid tumour
Answer: C: Carcinoid tumour 
Explanation: The leading cause of GHRH mediated acromegaly is chest or abdominal carcinoid tumour. It will present with elevated GH levels and pituitary enlargement on MRI leading to high probability of misdiagnosis as pituitary adenoma. GHRH levels can be used to differentiate a pituitary vs extra pituitary aetiology.