Confirmatory investigation for Acromegaly is:

Answer is B (Glucose induced GU suppression): The diagnosis of Acromegaly is confirmed by demonstrating the failure of GH suppression after an oral glucose load. Diagnosis of Acromegaly IGF - I level Age and gender matched serum IGF-I level are elevated in Acromegaly. Elevated IGF-I levels are primarily used as a screening test for Acromegaly and not as a confirmatory test. Random GH Assay GH secretion is episodic and serum concentrations of GH may fluctuate from undetectable levels to significantly high levels during the day. Due to pulsalilty of GH secretion, measurement of single random GH level is not useful for the diagnosis or exclusion of Acromegaly. GH suppression test (Failure of GH suppression in response to Glucose load) The diagnosis of Acromegaly is confirmed by demonstrating the failure of GH suppression to hours of an oral glucose load (75g). Infact, about 20% of patients exhibit a paradoxical rise in GH levels after glucose.