Biochemical markers (Table 831.1) can be measured in semen to test the secretions of accessory structures. These include fructose (seminal vesicles), zinc, citric acid or acid phosphatase (prostate), and α-glucosidase or carnitine (epididymis).
Table 831.1 Biochemical variables of semen analysis (World Helath Organization, 1992)
|1. Total fructose (seminal vesicle marker)||≥13 μmol/ejaculate|
|2. Total zinc (Prostate marker)||≥2.4 μmol/ejaculate|
|3. Total acid phosphatase (Prostate marker)||≥200U/ejaculate|
|4. Total citric acid (Prostate marker)||≥52 μmol/ejaculate|
|5. α-glucosidase (Epididymis marker)||≥20 mU/ejaculate|
|6. Carnitine (Epididymis marker)||0.8-2.9 μmol/ejaculate|
TEST FOR FRUCTOSE
Resorcinol method is used for detection of fructose. In this test, 5 ml of resorcinol reagent (50 mg resorcinol dissolved in 33 ml concentrated hydrochloric acid; dilute up to 100 ml with distilled water) is added to 0.5 ml of seminal fluid. The mixture is heated and brought to boil. If fructose is present, a red-colored precipitate is formed within 30 seconds.
Absence of fructose indicates obstruction proximal to seminal vesicles (obstructed or absent vas deferens) or a lack of seminal vesicles. In a case of azoospermia, if fructose is absent, it is due to the obstruction of ejaculatory ducts or absence of vas deferens, and if present, azoospermia is due to failure of testes to produce sperm.