Screening tests for Cushing Syndrome all except

Correct Answer: A

Rationale: Serum ACTH isn't a screening test for Cushing's differentiates cause (pituitary vs. adrenal) post-diagnosis. Late-night salivary cortisol, low-dose dexamethasone suppression, and dexamethasone-CRH screen hypercortisolism detect excess. ACTH's diagnostic role distinguishes it, key to etiology, not initial screening, unlike cortisol-based tests.

Correct Answer: C

Rationale: Drained volume >1000 mL predicts trial without catheter (TWOC) failure large residuals suggest poor bladder function or obstruction (e.g., BPH), needing prolonged catheterization. Absence of prior LUTS indicates better baseline favorable. Age <65 years ties to stronger detrusor supports success. High detrusor pressure aids voiding positive factor. High volume's negative impact distinguishes it, critical for TWOC prognosis, unlike factors enhancing bladder emptying potential.

Correct Answer: A

Rationale: Vasa recta surround the loop of Henle, enabling countercurrent exchange, unlike peritubular capillaries (PCT/DCT), interlobular arteries (cortex), or efferent arterioles (glomerulus). This specifies medullary circulation, key for urine concentration, contrasting with cortical vessels.

Correct Answer: B

Rationale: Renin cleaves angiotensinogen to angiotensin I, not angiotensin II (product), ACE (enzyme), or aldosterone (downstream). This initiates RAAS, key for blood pressure regulation, contrasting with subsequent steps.

Correct Answer: C

Rationale: PCT actively reabsorbs ~70% of filtered sodium, not 10%, 1%, or 99% (total includes later). This quantifies sodium handling, key for fluid balance, contrasting with full reabsorption myths.