A 68-year-old man with benign prostatic hyperplasia presents with lower urinary tract symptoms. Regarding the pathophysiology and medical management of BPH, all of the following statements are correct EXCEPT:

Question

Accepted Answer

B. Muscarinic antagonists are first-line agents for reducing prostate size and are superior to alpha-blockers in symptom relief. ## Pathophysiology and Medical Management of BPH

### Role of Alpha-1 Adrenergic Antagonists

**Key Point:** Alpha-1 blockers (tamsulosin, alfuzosin, doxazosin) are **first-line agents** for symptomatic BPH. They relax smooth muscle in the prostatic capsule, bladder neck, and proximal urethra, reducing dynamic outlet obstruction and improving flow rates within days to weeks.

### Role of 5-Alpha Reductase Inhibitors

**Key Point:** Finasteride and dutasteride block conversion of testosterone to dihydrotestosterone (DHT), the primary androgen driving prostate growth. These agents **reduce prostate volume by 20–30%** but require 6–12 months for maximal effect. They are indicated in men with large glands (>40 g) and are more effective at preventing progression than alpha-blockers.

### Role of Antimuscarinic Agents

**High-Yield:** Antimuscarinics (oxybutynin, tolterodine, solifenacin) are **NOT first-line** for BPH and do **NOT reduce prostate size**. They are reserved for **overactive bladder symptoms** (urgency, frequency) in men already on alpha-blockers. They work by relaxing detrusor muscle, not by shrinking the prostate. **Antimuscarinics are inferior to alpha-blockers as monotherapy** for BPH and carry risk of urinary retention in obstructed men.

**Warning:** The stem option claiming antimuscarinics are "superior to alpha-blockers in symptom relief" is **factually incorrect** — this is the wrong statement.

### Combination Therapy

**Clinical Pearl:** Alpha-blocker + 5-alpha reductase inhibitor combination is indicated in:
  - Large prostate (>40 g)
  - Moderate-to-severe LUTS
  - Elevated PSA
  - Risk of progression

This combination reduces symptom progression by ~65% compared to monotherapy [cite:Harrison 21e Ch 305].

### Summary Table

| Agent Class | Mechanism | Onset | Effect on Volume | First-Line? | Indication |
| --- | --- | --- | --- | --- | --- |
| Alpha-blockers | Smooth muscle relaxation | Days–weeks | Minimal | **Yes** | All symptomatic BPH |
| 5-alpha inhibitors | DHT reduction | 6–12 months | **20–30% reduction** | No (adjunct) | Large prostate, progression risk |
| Antimuscarinics | Detrusor relaxation | Variable | **None** | No | OAB symptoms only |

Answer

A. Alpha-1 adrenergic antagonists relax smooth muscle in the prostatic capsule and urethra, reducing outlet obstruction

Answer

C. 5-alpha reductase inhibitors block conversion of testosterone to dihydrotestosterone, reducing prostate volume over 6–12 months

Answer

D. Combination therapy with an alpha-blocker and 5-alpha reductase inhibitor is indicated in men with large prostates (>40 g) and moderate-to-severe symptoms

A 68-year-old man with benign prostatic hyperplasia presents with lower urinary tract symptoms. Regarding the pathophysiology and medical management of BPH, all of the following statements are correct EXCEPT:

Explanation

Practice similar questions