Benign Prostatic Hyperplasia Study Guide

Benign Prostatic Hyperplasia

Study guide:

Definition:
Benign prostatic hyperplasia is nonmalignant adenomatous overgrowth of the periurethral (transitional/central zone) prostate gland.

Epidemiology:

Affects ~ 70% by age 60 and surpasses 90% by age 80.
Family history of first degree relative is found in 90% of the cases.
Moderate to severe symptoms occur in about a third of the patients.
The prostate increases in volume by 2.4 cm3 per year on average from
40 years of age.

Pathophysiology:

Pathophysiology is not well understood yet.
Men castrated before puberty do not develop BPH when they age, supporting the androgen theory.
Excessive androgen → overgrowth of both stromal and glandular elements.

DHT (synthesized in the stromal cells) plays a major role → Stromal cells predominates the hyperplasia → occurs in the periurethral lobes (lateral and median lobes)→ Compression of the urethra → Bladder outflow obstruction →Lower urinary tract symptoms.
Increased sensitivity to DHT!
Activation of α1-adrenergic receptors of the prostate and bladder → smooth muscle contraction → further exacerbation of obstruction clinical symptoms.
Benign prostatic hyperplasia does not progress to prostate cancer.

Clinical Presentation:

Lower urinary tract symptoms:
- Related to storage:
  - Frequency.
  - Noctouria.
  - Dysuria.
  - Urgency.
  - Urge
  - incontinence.

Related to voiding:
- Hesitancy.
- Weak stream.
- Intermittency.
- Straining.
- Post void dribbling.

Diagnosis:

International Prostate Symptoms Score: A score used to assess the symptoms and quality of life

Digital rectal exam: This will reveal an enlarged prostate : Smooth, firm, and diffuse enlargement of prostate.
Transrectal ultrasonography (TRUS): Not indicated for the initial evaluation of uncomplicated LUTS, used to assess the size of the prostate.
Urodynamics: Useful for objective assessment of obstruction.
Blood test:
- Prostate specific antigen (PSA): To screen for prostate cancer, BPH does not cause prostate cancer, but men at risk of BPH are also at risk of cancer (in BPH it is usually <10 ng/mL).
- BUN, electrolytes, and creatinine: Not routinely done, useful to assess renal function in patients who have high postvoid residual (palpable bladder), nocturnal enuresis, recurrent UTI or a history of renal stones.
Urinalysis & Urine cultures: To rule out infections and hematuria.

Management:

Lifestyle modification: Decrease caffeine and alcohol intake, decrease water consumption before bedtime.
Watchful waiting: Used for patients with mild to moderate symptoms.
Medications:
- Non-selective α1 receptor blockers (terazosin):
  - MOA: Relaxes smooth muscle in the prostate and bladder neck, opposing α1-adrenoceptor-mediated prostatic growth, relieving the symptoms of obstruction. It also blocks the α1-B receptor blockers on blood vessels.
  - SE: Postural hypotension in normotensive patients, headache, and nasal congestion.
- Selective α1-A receptor blockers (tamsulosin):
  - MOA: used in normotensive patients as its mechanism of action is to block the α1-A receptors in the smooth muscles of the prostate and bladder and not the receptors on the smooth muscles of blood vessels, and thus not causing postural hypotension.
- 5α-reductase inhibitors:
  - MOA: Inhibits the conversion of testosterone to DHT (which has higher affinity in the prostate).
  - SE: Decreased libido, erectile dysfunction, and gynecomastia.
Surgical (reserved for patients with severe symptoms recalcitrant to medication):
- Transurethral resection of prostate (TURP).
- Holmium laser enucleation.
- Open prostatectomy.

Complications:

Recurrent Urinary tract infection: The presence of residual urine in the bladder due to chronic obstruction increases the risk.
Hydronephrosis: Severe BPH leads to complete urinary obstruction, with resultant painful distention of the bladder, if untreated could lead to hydronephrosis and postrenal failure.

References:

Kumar P, Clark M. Kumar & Clark's clinical medicine.
Kumar V, Abbas A, Aster J, Cotran R, Robbins S. Robbins and Cotran Pathologic Basis of Disease.
Rang H, Dale M. Rang and Dale's pharmacology. Edinburgh: Elsevier/Churchill Livingstone; 2012.
Le T, Bhushan V, Singh Bagga H. First aid for the USMLE step 2 CK. New York: McGraw-Hill Medical; 2010.
Le T, Krause K, Eby E. First aid for the basic sciences. New York: McGraw-Hill Medical; 2009.
Agabegi S, Agabegi E, Ring A. Step-up to medicine. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins; 2013.
Merck Manuals Professional Edition. Benign Prostatic Hyperplasia (BPH) - Genitourinary Disorders [Internet]. 2016 [cited 17 February 2016]. Available from: http://www.merckmanuals.com/professional/genitourinary-disorders/benign-prostate-disease/benign-prostatic-hyperplasia-(bph)
Commons.wikimedia.org. File:Benign Prostatic Hyperplasia nci-vol-7137-300.jpg - Wikimedia Commons [Internet]. 2016 [cited 17 February 2016]. Available from: https://commons.wikimedia.org/wiki/File:Benign_Prostatic_Hyperplasia_nci-vol-7137-300.jpg (Figure 1).
Medtronic-gastro-uro.com.au. Benign Prostate Health Symptom Score Index - Medtronic [Internet]. 2016 [cited 17 February 2016]. Available from: http://www.medtronic-gastro-uro.com.au/bph-symptom-score-index.html (Figure 2).

Written by: Lama Al Luhidan

Reviewed by: Bassam AlGhamdi

Roaa Amer

Format editor: Adel Yasky

Audio recording:

Read by: Bayan Alzomili

Directed by: Rana Alzahrani

Audio production: Bayan Alzomaili