From the Guidelines
Prostate enlargement causing obstructive urinary symptoms typically occurs when the prostate reaches approximately 30 grams or larger. The normal prostate weighs about 20-25 grams, and as it grows beyond this size, it can begin to compress the urethra and cause symptoms such as weak urine stream, hesitancy, incomplete emptying, frequency, urgency, and nocturia. However, the correlation between prostate size and symptom severity is not always straightforward. Some men with moderately enlarged prostates (30-50 grams) may experience significant symptoms, while others with larger prostates (>80 grams) might have minimal complaints. This variability occurs because symptoms depend not only on absolute size but also on factors like the direction of prostate growth (whether it grows into the bladder or compresses the urethra), bladder muscle function, and individual anatomical differences. Key factors to consider in the management of lower urinary tract symptoms (LUTS) attributed to benign prostatic hyperplasia (BPH) include prostate volume and PSA threshold, as indicated in the AUA guideline 1. For instance, a minimum prostate volume of >30cc or PSA >1.5ng/mL is necessary for a reliable response to 5-alpha reductase inhibitors (5-ARIs) like finasteride or dutasteride 1. Treatment approaches range from watchful waiting for mild symptoms to medications (alpha-blockers like tamsulosin or 5-alpha reductase inhibitors like finasteride) for moderate symptoms, to surgical interventions for severe enlargement causing significant obstruction or complications. It's also worth noting that 5-ARIs can reduce the size of the prostate by 15-25% at six months, leading to a reduction in androgenic growth and an increase in apoptosis and atrophy, which can help alleviate symptoms 1. In terms of specific medications, finasteride and dutasteride have been shown to be effective in improving standardized symptom scores, with improvements of 3 to 4 points observed and maintained for 6 to 10 years of follow-up 1. Ultimately, the management of LUTS/BPH should be individualized based on the patient's symptoms, prostate size, and PSA level, as well as other factors such as bladder muscle function and individual anatomical differences.
From the Research
Prostate Size and Obstructive Symptoms
- The relationship between prostate size and obstructive symptoms is complex, and symptoms do not always correlate with prostate size 2.
- A study found that a prostate volume over 40 ml had a positive predictive value for infravesical obstruction of 76% 2.
- However, another study noted that prostate size, symptomatology, and bladder outflow obstruction are distinct concepts that should be considered separately in the evaluation of patients with symptomatic BPH 2.
Prostate Size in Grams and Obstruction
- Unfortunately, there is no direct information available on the specific prostate size in grams that can cause obstructive symptoms.
- Prostate size is typically measured in milliliters (mL) or cubic centimeters (cc), rather than grams.
- A study mentioned that patients with prostate volumes of 87.8 mL and 85.4 mL had similar baseline characteristics, including obstructed urodynamic studies (UDS) 3.
Treatment and Prostate Size
- Finasteride, a 5-alpha reductase inhibitor, has been shown to reduce prostate size and improve symptoms in patients with BPH 4, 5.
- Prostate artery embolization (PAE) has also been found to be effective in reducing prostate size and improving symptoms in patients with BPH 3.
- The choice of treatment depends on various factors, including the severity of symptoms, prostate size, and patient preferences 6, 5.