Approximately 30 per cent of the practice of a urologist is dedicated to treating diseases of the prostate gland. This organ attracts a lot of attention because of cancer cases and related public education campaigns. However, many people are unaware of the location and function of the prostate gland. This will be my focus today.

The prostate gland is an organ located in the pelvis, beneath the bladder, in front of the lower rectum and behind the pubic bone. The urinary tube called the urethra traverses the course of the prostate, carrying urine out of the body. Most articles describe the prostate as being the size of a walnut. For those of us who may not regularly see walnuts, the prostate in young men is about 20 grams, the size of a small plum or guinep. However, the organ increases in size with age.

The growth of the prostate is mediated by several factors, inclusive of hormones and growth factors. The testes make 85-90 per cent of the male hormone, testosterone. This hormone is converted to an even more active hormone, dihydrotestosterone (DHT), by enzymes within the prostate. It is the DHT that is responsible for the growth of the prostate. If a male child has absence of the critical enzyme (5-α reductase) then the prostate gland will not develop. This fact was recognised after the discovery of a group of males in a small village in the Dominican Republic who had a congenital absence of 5-α reductase. They were pseudohermaphrodites and physically appeared as females until puberty. These individuals, referred to as “guevedoces” in the Dominican Republic did not develop a normal penis until age 12 years and always had a small prostate. This clinical observation combined with other research resulted in the discovery of a group of drugs to treat adult males with a benign enlarged prostate.

The prostate gland is considered an “accessory sex gland”. Its internal structure consists of a mixture of fibrous tissue and glands. These glands produce secretions which form part of seminal fluid (semen). In fact, the prostate contributes 25 per cent (0.5 ml) of seminal fluid. This fluid is thought to provide a protective effect for sperm, optimising the potential for fertilisation. Zinc and citrate are found in high concentration in the prostate gland. Citrate is present 240 to 300 times the concentration found elsewhere, and zinc is found 30 times the concentration elsewhere. It is thought that these two substances help to maintain the structure of sperm. Additionally, zinc has potent antimicrobial properties thereby having a protective effect on the lower urinary tract. Another substance found in prostate is prostate specific antigen (PSA), which is universally utilised as a tumour marker for prostate cancer. However, physiologically this protein has a role in semen liquefaction thereby increasing sperm motility. Polyamines and acid phosphatase are also found in the prostate. The prostate, which contains smooth muscle, plays an integral part in the process of emission which occurs prior to ejaculation.

The prostate gland is, therefore, necessary for normal male reproductive function. However, there are diseases that may frequently affect this gland. These include benign enlargement, cancer, infection and inflammation. Men can live normal lives in the absence of a prostate and at times surgery is recommended for treatment of some diseases of the prostate. I will discuss these diseases in upcoming issues as well as means to maintain a healthy prostate.

Dr Belinda Morrison

Senior Lecturer and Consultant Urologist

The University of the West Indies