Osmolality and conductance of normal and abnormal human seminal plasma.

The possible correlation between two important general properties of seminal plasma, osmolality and conductance, and the presence of some pathological conditions of human semen, asthenospermia and oligoasthenospermia, have been studied. Osmolality was measured under carefully controlled conditions by the freezing point depression method and conductance with a Wheatstone bridge. In addition, volume, by an isotopic dilution method, and pH were also determined. Osmolality of normal human seminal plasma (366 +/- 16 mOsm/Kg) was found to be higher than the osmolality of human blood serum. Abnormal seminal plasma showed a still higher value (428 +/- 38 and 457 +/- 49 mOsm/Kg respectively for astheno- and oligoasthenospermic subjects). Incubation of normal seminal plasma for 24 hours at room temperature produced a significant increase in osmolality (from 366 +/- 16 to 430 +/- 31 mOsm/Kg) while pathological seminal plasma failed to show any modification. Osmolality and conductance values were found to be correlated with semen ejaculated volume in normal subjects. No difference in mean conductance value was found between normal and asthenospermic individuals (10.4 +/- 1.2 against 9.9 +/- 1.0 mhos X 10(-3) respectively). Oligoasthenospermics showed, on the contrary, a significantly higher conductance (12.4 +/- 1.6 mhos X 10(-3)).