白袍恐懼症

Benign prostatic hyperplasia (BPH)

1.      INTRODUCTION

-A common disorder that increases in frequency progressively with age in men older than 50 years.

2.      Mechanism

-BPH和androgen 有密切相關

-prostate 裡的stromal cell含有type 2 的5α-reductase

-type 2 的5α-reductase使 testosterone→DHT(dihydrotestosterone) 

- DHT使epithelial cell hyperplasia

- hyperplasia主要發生在transitional zone和periurethral zone(prostate內側)

-一般而言，組織病理學上發現有攝護腺肥大的病患僅50%臨床上可發現攝護腺變大，而攝護腺變大的病患只有50%出現臨床症狀。

3.      CLINICAL

-Lower urinary tract symptoms (LUTS): increased frequency of urination, nocturia, hesitancy, urgency, and weak urinary stream.

- digital rectal examination: 正常男性的攝護腺摸起來為圓心型構造，長約2.5公分，兩葉之間可以摸到central sulcus，攝護腺具有橡皮般的彈性。BPH的患者攝護腺摸起來較為平實堅硬，central sulcus可能不明顯，通常會有對稱性變大並且突入rectum space。( prostate size和symptoms非正相關)

-Transrectal ultrasonographic: enlargement of the transitional zone of the prostate.

-Urinalysis

- Serum creatinine

4.      NATURAL HISTORY 

-Age, symptoms, urinary flow rate and prostate volume are risk factors for acute urinary retention

-Serum PSA is a stronger predictor of prostate growth than age or baseline prostate volume

-BPH is not believed to be a risk factor for prostate cancer, although studies have come to conflicting results

- BPH occurs primarily in the central or transitional zone of the prostate, while prostate cancer originates primarily in the peripheral part of the prostate.

5.      DIAGNOSTIC APPROACH 

(1). D/D by history

History of type 2 diabetes=> nocturia=> a risk factor for BPH

Symptoms of neurologic disease => neurogenic bladder

Sexual dysfunction=> LUTS

General health and fitness for possible surgical procedures

Gross hematuria or pain in the bladder region => bladder tumor or calculi

History of urethral trauma, urethritis, or urethral instrumentation => urethral stricture

Family history of BPH and prostate cancer

Treatment with drugs that can impair bladder function (anticholinergic drugs) or increase outflow resistance (sympathomimetic drugs)

  (2). American Urologic Association symptom score (AUA, IPSS)

The International Prostate Symptom Score (IPSS) uses the same questions and scale as the AUA symptom score and adds a disease-specific quality of life question: "If you were to spend the rest of your life with your urinary condition the way it is now, how would you feel about that?"

(3). PE

Digital rectal examination: prostate size and consistency and to detect nodules, induration, and asymmetry, all of which raise suspicion for malignancy. Rectal sphincter tone should be determined, and a neurological examination performed.

(4). Urinalysis

Detect urinary infection and blood, which could indicate bladder cancer or calculi. There is some controversy about whether hematuria is more common in patients with benign prostatic hyperplasia (BPH) than in age-matched controls. However, there is general agreement that the presence of BPH should not dissuade the clinician from pursuing further evaluation of hematuria, particularly since older men are more likely to have more serious disorders such as cancer of the prostate or bladder.

6.      TEST

Measurements of serum PSA, maximal urinary flow rate, and post-void residual urine are optional, but are useful in most men. The performance of other tests (pressure-flow studies, urethrocystoscopy, intravenous urography, ultrasonography and abdominal x-rays) should be reserved for unusual patients and for those being considered for invasive treatments.

7.    Treatment

(1). Mild BPH(IPSS score< 7):觀察即可，42%的病患症狀會改善。觀察期間
要告知可能的併發症，包括急慢性的尿液滯留、反覆的UTI、膀胱結石等等。

(2). Moderate BPH(IPSS score>8):內科治療

α-blocker(最常用)，可降低攝護腺及膀胱頸平滑肌的張力(smooth muscle 
tone)以改善症狀，α-blocker約可改善50%的尿流速度及60-80%的症狀。
doxazosin、terazosin和prazosin屬於非選擇性的α-blocker，前兩者除了用
於攝護腺肥大外對高血壓的控制也有幫助，非選擇性的α-blocker副作用
發生率約7-9%，包括頭暈、姿勢性低血壓、虛弱無力、鼻塞等等。這些
副作用通常都很輕微。睡前給藥而且由低劑量開始給予可以減少副作用
發生的機會。許多研究認為非選擇性性的α-blocker並不會降低正常人的
血壓，不過臨床醫師仍應定期監測病患的血壓。Tamsulosin是高度選擇
性的α1A-blocker，副作用較少而且也不會降低血壓，不過有高達15%的
病患出現射精功能障礙。

5α-reductase inhibit (ex. Finasteride )，抑制5α-reductase以減少testosterone
被轉變為DHT，治療3到6個月後攝護腺的體積約可減少20%。對於攝護腺
體積較大的患者finasteride可以減少急性尿液滯留和接受手術治療的機會
，不過總體而言finasteride的效果仍比α-blocker差，此藥必須使用6-12個
月才能達到完全的效果而且使用12個月後症狀改善率只有20-30%。健保
規定finasteride為攝護腺肥大的第二線用藥，經直腸超音波(TRUS)發現攝
護腺體積大於20 gm或尿路動力學檢查顯示尿流速小於15 ml/sec時才可使
用，副作用發生率約4-5%，包括性慾降低、陽痿和射精障礙，值得注意
的是finasteride會降低40-50%的PSA值，有可能影響攝護腺癌的早期診斷。

(3). Severe BPH(IPSS score>20內科治療失敗的患者): 手術治療

transurethral resection of prostate (經尿道攝護腺切除術, TURP)是最常用的
手術方式，約88%的患者可以改善症狀。TURP較為安全且整體的手術死
亡率只有0.2%，手術的後遺症包括無法解尿、出血、次發性感染、低血
鈉症(dilutional hypernatremia)等等，長期的併發症以逆行性射精
(retrograde ejaculation)佔最多數，高達70%的患者出現此併發症，其次是
陽痿(5-10%)及尿失禁(2-4%)。約有10%的患者五年後需要再治療。

Open prostatectomy是經由恥骨上(suprapubic)或恥骨(retropubic)的途徑切
除攝護腺的內側的組織，約98%的患者可以獲得改善，是最有效的手術
方式。由於具高度侵襲性、易出現併發症且手術死亡率高，一般建議用
於結構異常如攝護腺很大的病患。

TUIP(transurethral incision of the prostate)是利用內視鏡在攝護腺尿道靠近
膀胱頸處做一兩道切口讓膀胱頸打開以減輕膀胱出口的阻力，TUIP主要
是針對攝護腺體不大，確實際造成膀胱出口阻塞的病患，手術時間短且
治療效果並不亞於TURP。TUIP較不會引起性功能障礙，術後出血的情形
也比TURP輕微，不過缺乏長期滿意度和再治療率的研究報告。其他較新
的手術包括TUMT(transurethral microwave thermotherapy)、 TUVP
(trensurethral vaporization of the prostate)、TUNA
(transurethral needle ablation of the prostate)等等，顧名思義這些手術方法
是利用微波(microwave)、電極(electrode)、雷射(laser)或射頻
(radiofrequency)來破壞增生的攝護腺組織，具有低侵襲性且併發症少的
優點，雖然目前這些手術方式並沒有被廣為接受，不過使用率已有逐漸
增加的趨勢。

參考資料:http://www.tafm.org.tw/Data/011/161/181202.htm