The prostate is a small, muscular gland that is a part of the male reproductive system. This organ is situated just below the bladder, positioned in front of the rectum, and it wraps around the urethra. Its primary biological function is to produce and secrete seminal fluid, which nourishes and transports sperm during ejaculation. Understanding the size of this gland is often the first step in addressing common urinary issues that develop as men age.
Normal Prostate Dimensions and Measurement
For a healthy, young adult male, the prostate is compared in size to a walnut or a chestnut. The average adult prostate weighs between 15 and 25 grams. Clinicians refer to the volume, which measures around 20 to 25 cubic centimeters (cc) or milliliters (ml) in men under the age of 40.
Prostate size is assessed using standard methods. The simplest is the Digital Rectal Exam (DRE), where a doctor manually feels the gland through the rectal wall to estimate its size, shape, and consistency. For a more precise measurement of the prostate’s volume, doctors use a Transrectal Ultrasound (TRUS). This imaging technique provides accurate dimensions used to calculate the volume.
Natural Changes in Size Over a Lifetime
The prostate gland experiences two distinct phases of growth throughout a man’s life. The first phase occurs during puberty, driven by hormonal changes, where the gland roughly doubles in size. The prostate reaches its adult dimensions by the time a man is in his early twenties.
The second phase of growth begins around age 25 and continues indefinitely. This gradual increase in tissue volume is a natural part of aging. The rate of growth varies significantly among individuals, explaining why prostate size differs even among healthy men of the same age.
Benign Prostatic Hyperplasia (BPH)
The continuous, age-related enlargement of the prostate is known as Benign Prostatic Hyperplasia (BPH). The term “benign” signifies that this growth is non-cancerous, but the increase in size can still lead to disruptive urinary symptoms. BPH affects many men starting around age 40 and becomes increasingly prevalent with each passing decade.
The enlargement occurs in the transition zone of the prostate, the tissue directly surrounding the urethra. As this tissue expands, it compresses the urethra, creating a physical obstruction to the flow of urine. This mechanical blockage causes the symptoms associated with an enlarged prostate.
The actual size of the prostate gland does not necessarily determine the severity of symptoms. A man can have a very large prostate and experience no bothersome symptoms. Conversely, a man with a mildly enlarged prostate may experience significant urinary difficulty due to the precise location of the growth. Symptoms are caused by the degree of obstruction, not just the overall volume of the gland.
Recognizing Symptoms and Seeking Evaluation
Changes in prostate size often manifest as Lower Urinary Tract Symptoms (LUTS). These symptoms are grouped into two categories: voiding and storage. Voiding symptoms include a weak or slow urinary stream, difficulty starting urination (hesitancy), straining to empty the bladder, and dribbling at the end of urination.
Storage symptoms relate to how the bladder holds urine. These include increased frequency of urination, a sudden, urgent need to urinate, and waking up multiple times at night (nocturia). If these symptoms interfere with daily life or sleep, consult a healthcare provider. Ignoring these changes can lead to complications, such as urinary tract infections or bladder damage.
The initial evaluation involves a detailed discussion of symptoms, followed by a Digital Rectal Exam (DRE). Doctors may also order a Prostate-Specific Antigen (PSA) blood test, which measures a protein produced by the gland. Additional tests may include uroflowmetry to measure the speed of the urine stream and a post-void residual volume test to determine how much urine remains in the bladder after voiding.