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Stem
A 48-year-old man is referred by his dentist, who noticed widening gaps between his teeth and an enlarged jaw. Over five years his shoe size has risen from 9 to 12, his wedding ring no longer fits, and his wife says his face has coarsened with a prominent brow and jaw. He snores heavily and sweats at night. Examination: BP 158/96, prognathism, frontal bossing, macroglossia, spade-like hands, oily skin, and a bitemporal superior quadrantanopia. Random plasma glucose is 9.6 mmol/L.
Questions
a) What is the most likely diagnosis? Give two clinical features from the stem that support it. (2 marks)
Model answer: Acromegaly (1 mark). Any two of: acral enlargement (shoe and ring size up, spade-like hands), facial coarsening (prognathism, frontal bossing, macroglossia, widened teeth gaps), bitemporal field defect from chiasmal compression, or new hypertension/diabetes/snoring (1 mark).
b) Outline the biochemical investigation, naming the screening and confirmatory tests with their expected results. (3 marks)
Model answer: Screening: serum IGF-1, elevated for age and sex (1). Confirmatory: 75 g oral glucose tolerance test — GH fails to suppress to under 1 ng/mL (under 0.4 with sensitive assays) (1). Localise with pituitary MRI; assess the other anterior pituitary axes (cortisol, free T4, gonadal, prolactin) and screen comorbidities — glucose, echocardiogram, sleep study, colonoscopy, visual fields (1).
c) Describe the first-line treatment and two medical options for residual disease. (3 marks)
Model answer: First-line: transsphenoidal resection of the somatotroph adenoma, curative if complete (1). Residual or inoperable disease: somatostatin analogues (octreotide LAR, lanreotide) that suppress GH secretion (1); pegvisomant, a GH receptor antagonist that blocks GH action and normalises IGF-1 (1). Cabergoline or stereotactic radiotherapy are alternatives.
d) Name two important complications and state the leading cause of death. (2 marks)
Model answer: Any two of: acromegalic cardiomyopathy/heart failure, type 2 diabetes, obstructive sleep apnoea, colonic polyps or colorectal cancer, arthropathy, carpal tunnel syndrome, hypopituitarism (1). Leading cause of death: cardiovascular disease (1).