The Influence of the Sampling Point on Testicular Steroid Concentrations in Spermatic Venous Blood: A Physiological Approach to Evaluate Testicular Secretion

Abstract

In the present study, we have evaluated the influence of the location of the blood sampling in the spermatic vein on the steroid concentrations observed. Simultaneous blood sampling at two different points of the spermatic vein (iliac level and pampiniform plexus) was perfomed in the same patients during a surgical protocol for varicocelectomy. In order to further evaluate which of the two sampling points is more useful to investigate testicular secretion, we have performed both forms of sampling in 4 volunteers given an HCG stimulation 24 h before the surgical procedure. It was found that levels of testosterone (T) and 17α-hydroxyprogesterone (17-OHP) were higher in the pampiniform plexus (scrotal) than at the iliac sampling point (T scrotal 1,168.343 ± 142.65 nmol/l, iliac 850.63 ± 143.411 nmol/l, n = 21, p < 0.01; 17-OHP scrotal 260.130 ± 43.14 nmol/l, iliac 164.46 ± 31.02 nmol/l, n = 17, p < 0.01). This indicates that spermatic blood collected at the scrotal sampling point has received more blood coming from the testis than the blood collected at the iliac point. We did not observe significant differences in progesterone and Δ4-androstene-dione (Δ4) levels between the two samplings. The T/Δ4 ratio was significantly lower in the iliac than in the scrotal sampling (T/Δ4 scrotal 31.420 ± 6.69; iliac 15.41 ± 3.84; p < 0.05). After HCG stimulation, testosterone concentrations were higher in the pampiniform plexus than in the iliac sample. This suggests that the first sampling point is more proper for studying testicular secretion. Both T/Δ4 and T/17-OHP ratios were significantly higher at the iliac sampling (median T/Δ4 scrotal 33.909, iliac 17.64, 0.03 > p > 0.02; median T/17-OHP scrotal 4.86, iliac 3.06, p < 0.05). These results show that the ratio between testosterone and its precursors is also influenced by the point of blood collection in the spermatic vein.