Common causes of BPH and Pathophysiology
The outcome of BPH depends on two major factors i.e.
- Anatomical factors: These involve enlargement of the Prostate gland which produces a physical blockage at the neck of the bladder against urinary flow. This results in increased responsiveness of the prostate gland to androgens and estrogens.
- Dynamic factors; These result from excessive sympathetic stimulation via alpha-1 receptors in the prostate gland leading to increased tone at the sphincters of urinary bladder and the prostate.
The pathophysiology of BPH is as follows:
- Resistance. BPH is a result of complex interactions involving resistance in the prostatic urethra to mechanical and spastic effects.
- Obstruction. The hypertrophied lobes of the prostate may obstruct the bladder neck or urethra, causing incomplete emptying of the bladder and urinary retention.
- Dilation. Gradual dilation of the ureters and kidneys can occur.
Resulting symptoms of BPH.
- Urinary frequency. Frequent trips to the bathroom to urinate may be an early sign of a developing BPH.
- Urinary urgency. This is the sudden and immediate urge to urinate.
- Nocturia. Urinating frequently at night is called nocturia.
- Weak urinary stream. Decreased and intermittent force of stream is a sign of BPH.
- Dribbling urine. Urine dribbles out after urination.
- Straining. There is presence of abdominal straining upon urination.
- Urinary retention
- Decrease in force of urinary out put
- Intermittency during urination
Investigations and Diagnosis of BPH
- Digital rectal examination (DRE). A DRE often reveals a large, rubbery, and nontender prostate gland.
- Urinalysis. A urinalysis to screen for hematuria and UTI is recommended.
- Prostate specific antigen levels. A PSA level is obtained if the patient has at least a 10-year life expectancy and for whom knowledge of the presence of prostate cancer would change management.
- Urinalysis: Color: Yellow, dark brown, dark or bright red (bloody); appearance may be cloudy. pH 7 or greater (suggests infection); bacteria, WBCs, RBCs may be present microscopically.
- Urine culture: May reveal Staphylococcus aureus, Proteus, Klebsiella, Pseudomonas, or Escherichia coli.
- Urine cytology: To rule out bladder cancer.
- BUN/Cr: Elevated if renal function is compromised.
- Prostate-specific antigen (PSA): Glycoprotein contained in the cytoplasm of prostatic epithelial cells, detected in the blood of adult men. Level is greatly increased in prostatic cancer but can also be elevated in BPH. Note: Research suggests elevated PSA levels with a low percentage of free PSA are more likely associated with prostate cancer than with a benign prostate condition.
- WBC: May be more than 11,000/mm3, indicating infection if patient is not immunosuppressed.
- Uroflowmetry: Assesses degree of bladder obstruction.
- IVP with post voiding film: Shows delayed emptying of bladder, varying degrees of urinary tract obstruction, and presence of prostatic enlargement, bladder diverticula, and abnormal thickening of bladder muscle.
- Voiding cystourethrography: May be used instead of IVP to visualize bladder and urethra because it uses local dyes.
- Cystometrogram: Measures pressure and volume in the bladder to identify bladder dysfunction unrelated to BPH.
- Cystourethroscopy: To view degree of prostatic enlargement and bladder-wall changes (bladder diverticulum).
- Cystometry: Evaluates detrusor muscle function and tone.
- Transrectal prostatic ultrasound: Measures size of prostate and amount of residual urine; locates lesions unrelated to BPH.
Classification of drugs for BPH
They are classified into 3 major groups;
- 5 alpha-reductase inhibitors
- Alpha-1 selective blockers
- Combined therapies
5 alpha-reductase inhibitors
They inhibit an enzyme 5 alpha – reductase in the prostate thus preventing the conversion of testosterone into active form thus suppressing the activity of androgens in the prostate. The overall effect is decreased growth of the prostate gland.
N.B the effects of these drugs is not prompt and don’t relieve urine retention.
- Finasteride 5mg o.d.
- Dutasteride 0.5mg o.d
Both are administered orally
Alpha – 1 selective blockers
They block alpha I receptors in the prostate and bladder leading to relaxation of sphincter and so improved urine flows.
These are grouped into two;
- Short acting agent e.g. Prazosin, Indamine, and Alfuzosin.
- Long acting agents e.g. Tamucurosin, Doxazocin and Terazosin.
Doses;
- Prazosin 0.5-1mg o.d given at bed time after few days orally then maintained at 1mg b.d * 3/7
- Terazosin 2-10mg o.d
- Doxazocin 1mg o.d.
- Tamucurosin 0.4 mg once daily given with meals orally.
NB: Tamucurocin is a long acting member best indicated since doesn’t interfere with blood pressure
Trazocin should be given at a lower dose then maintained later this is to avoid hypotension while standing
Their effects are faster thus usually combined with Finasteride
Adverse effects:
- Postural hypotension
- Tachycardia reflex
Others rarely used members include; Phentolamine and phenoxybenzamine
Medical Management
The goals of medical management of BPH are to improve the quality of life and treatment depends on the severity of symptoms.
- Catheterization. If a patient is admitted on an emergency basis because he is unable to void, he is immediately catheterized.
- Cystostomy. An incision into the bladder may be needed to provide urinary drainage.
Pharmacologic Management
- Alpha-adrenergic blockers (eg, alfuzosin, terazosin), which relax the smooth muscle of the bladder neck and prostate, and 5alpha reductase inhibitors.
- Hormonal manipulation with antiandrogen agents (finasteride [Proscar]) decreases the size of the prostate and prevents the conversion of testosterone to dihydrotestosterone (DHT).
- Use of phytotherapeutic agents and other dietary supplements (Serenoa repens [saw palmetto berry] and Pygeum africanum [African plum]) are not recommended, although they are commonly used.
- One herbal medication effective against BPH is Saw Palmetto.
Surgical Management
Other treatment options include minimally invasive procedures and resection of the prostate gland.
- Transurethral microwave heat treatment. This therapy involves the application of heat to prostatic tissue.
- Transurethral needle ablation (TUNA). TUNA uses low-level radio frequencies delivered by thin needles placed in the prostate gland to produce localized heat that destroys prostate tissue while sparing other tissues.
- Transurethral resection of the prostate (TURP). TURP involves the surgical removal of the inner portion of the prostate through an endoscope inserted through the urethra.
- Open prostatectomy. Open prostatectomy involves the surgical removal of the inner portion of the prostate via a suprapubic, retropubic, or perineal approach for large prostate glands.