Endocrinology & Diabetes — Flashcards

Flashcard 51: What is the next step in imaging for a patient with biochemically confirmed Cushing's Syndrome?

Answer: Imaging depends on the etiology (after biochemical confirmation): - Cushing Disease (Pituitary): MRI Brain/Pituitary - Adrenal Cushing: CT Adrenals - Ectopic ACTH: CT Chest/Abdomen/Pelvis

Extra: Cushing's syndrome imaging should only be performed AFTER biochemical confirmation of hypercortisolism. 1. If ACTH is low (<5 pg/ml) -> ACTH-independent -> CT Adrenals. 2. If ACTH is high (>20 pg/ml) -> ACTH-dependent -> MRI Pituitary (first-line). 'CT Adrenals' alone is incorrect as the most common cause of endogenous Cushing's is a pituitary adenoma (Cushing Disease).

Flashcard 52: Best test to diagnose Cushing's syndrome?

Answer: Any of the following (First-line screening): 1. Low-dose dexamethasone suppression test (LDDST) 2. 24-hr urinary free cortisol 3. Late-night salivary cortisol

Extra: Once hypercortisolism is confirmed with at least two abnormal first-line tests, the next step is checking plasma ACTH levels to differentiate between ACTH-dependent and ACTH-independent causes.

Flashcard 53: With hypercalcaemia caused by malignancy, what will PTH and PTHrP be?

Answer: • PTH low -> negative feedback of hypercalcaemia • PTHrP high -> released from the tumour e.g. sqamous cell lung cancer

Flashcard 54: Hypoglycaemia with High Insulin levels, but Low C-peptide?

Answer: • Exogenous Insulin Administration • aka Insulin Overdose

Flashcard 55: What is the maximum dose of metformin in T2DM management?

Answer: 2550 mg/day (often rounded to 2.5g) for immediate release; 2000 mg/day for extended release.

Extra: Standard dosing usually starts at 500mg once or twice daily and is titrated up. The FDA-approved maximum for immediate-release metformin is 2550 mg/day given in divided doses.

Flashcard 56: What diabetes medication may cause fluid retention?

Answer: • Pioglitazone *Thiazolidinedione

Flashcard 57: What should be done to an Addison's patients steroid replacement during intercurrent illness?

Answer: • Double the glucocorticoids • Keep fludrocortisone the same *during illness the body usually increases cortisol production as a stress response

Flashcard 58: What is the first-line investigation in suspected primary hyperaldosteronism?

Answer: • Aldosterone/renin ratio

Flashcard 59: Which diabetes medication may have to be stopped in AKI due to risk of toxicity (but doesn’t usually worsen AKI itself)?

Answer: Metformin

Flashcard 60: In T2DM management when should SGLT-2 inhibitors be introduced?

Answer: • Established Cardiovascular Disease (e.g., IHD, Stroke, PAD) • Heart Failure • Chronic Kidney Disease (CKD) • QRISK3 score ≥ 10%

Extra: Current NICE guidelines (NG28) recommend early introduction of SGLT-2 inhibitors (alongside metformin) for patients with T2DM and chronic heart failure or established atherosclerotic cardiovascular disease. They should also be offered if the QRISK3 is ≥ 10% or if the patient has CKD.