What zones of the prostate do BPH and prostate cancer affect?
BPH = transitional zone
Prostatic cancer = peripheral zone
What are the functions of the bladder?
What does the prostate gland secrete? What does this fluid contain?
Slightly alkaline fluid (30% of semen volume), milky/ white colour. Mixture of sugar (energy for the sperm), enzymes and alkaline chemicals. It contains:
- Proteolytic enzymes= breaks down coagulants and proteins to liquefy the semen
- Citric acid
- PSA
- Prostaglandins
What initiates cell growth of the prostate?
Testosterone from the testicles travels to the prostate and is converted to dihydrotestosterone (DHT) via enzyme 5a-reductase. DHT is more potent than testosterone at initiating growth
What area of the brain is involved in the storage and voiding of urine?
Pontine continence centre in the pons = storage
Pontine micturition centre in pons = voiding
What innervates the bladder for storing urine? What does this nerve cause upon stimulation?
Hypogastric nerve (sympathetic)- releases NA:
- Relaxation of detrusor muscle via stimulation of B3-adrenoceptors
- Contraction of internal urethral sphincter via a-1 adrenoceptors
What is receptive relaxation?
As the bladder fills, the detrusor muscle relaxes and sphincters contract. The rugae flatten to increase volume and keep intra-vesicle pressure constant (and lower than urethral pressure).
What innervates the bladder for voiding urine? What does this nerve cause upon stimulation?
Pelvic splanchnic nerve (parasympathetic)- releases ACh:
- Contraction of detrusor muscle via M3 receptors (increases intra-vesicle pressure)
How does BPH manifest? i.e. causes
Aging associated with an enlarged prostate = non-cancerous hyperplasia. Involves proliferation of glandular tissue in the transitional zone. Forms large nodules in the transition zone.
May be due to:
- Impaired apoptosis
- Increased DHT (5a-reductase enzyme increases, so although testosterone declines, DHT is higher)
- Altered estrogen/androgen ratio (increases, i.e. more estrogen, stimulates growth of prostate)
What storage symptoms may be present with BPH?
What voiding symptoms may be present with BPH?
What are some complications of BPH?
When is BPH most common (age)?
50-65
What are some risk factors for BPH?
What investigations may be carried out if BPH was suspected?
What might you feel during a DRE for BPH?
firm, smooth, symmetrical enlarged prostate
After presenting with LUTS symptoms for the first time, should all men have a PSA test?
If aged >50 years (or >40yrs if Black African or Caribbean)
What scan may be done for a BPH diagnosis? What would indicate enlargement of the prostate?
Ultrasound: if prostate >30ml then enlarged (normal 20-25ml /g)
What medication may patients with BPH be started on? (with moderate-severe symptoms)
For alpha-1a blockers, give an example, their MOA, contraindications and side effects
Tamulosin or silodosin
MOA: blocks alpha-1a adrenoceptors in the smooth muscle of prostate and bladder. Reduces obstruction; dynamic component of BPH
Side effects: headaches, postural HTN, retrograde ejaculation, dizziness, sexual dysfunction
Contraindications: history of postural hypotension
Give the benefits of alpha-1a selective blockers over alpha-1 blockers
Less likely to cause heart failure (the predominant receptor in the prostate and bladder neck is 1A so its more specific)
Give an advantage of alpha blockers over 5a-reductase inhibitors
Quick, symptomatic relief within a few days, whereas 5a reductase inhibitors can take months to improve symptoms
For 5a-reductase inhibitors, give an example, their MOA, contraindications and side effects
Finasteride or dutasteride
MOA: inhibit 5a-reductase to reduce the conversion of testosterone to DHT, thereby reducing size of the prostate (static component)
Side effects: sexual dysfunction
Dutasteride: contraindicated in liver disease
How do phosphodiesterase-5 inhibitors work?
Relax smooth muscle by prolonging NO (dynamic component of BPH)