L. Ekelund et Cb. Laurell, THE PREGNANCY ZONE PROTEIN RESPONSE DURING GESTATION - A METABOLIC CHALLENGE, Scandinavian journal of clinical & laboratory investigation, 54(8), 1994, pp. 623-629
Prospective studies of pregnant women were performed to compare indivi
dual variations in the plasma concentration of sex hormone binding glo
bulin (SHBG) and pregnancy zone protein (PZP) during pregnancy, and to
elucidate the degree of co-variation between these oestrogen sensitiv
e proteins during gestation. The plasma concentration of SHBG manifest
ed continuous increase reaching a 12-fold peak at delivery. The increa
se of the protease inhibitor PZP paralleled that of SHBG reaching a pe
ak with a 25-fold increase by the beginning of the third trimester. Th
en it started to decline, while that of SHBG continued to increase. Th
e synthesis of the protease inhibitor may also continue to increase du
ring late gestation but its elimination from the circulation may be ac
celerated when the syncytiotrophablastic area in contact with the mate
rnal blood approaches its maximum. The unusually wide individual varia
tion of PZP concentrations in nonpregnant women was confirmed. However
, the individual levels increased proportionally during the progress o
f pregnancy, and we may speak of low, medium and high reactors for PZP
. One initial conclusion to be drawn from the present findings is that
the value of the plasma PZP concentration can only be interpreted fro
m a pathophysiologic point of view if the patient's baseline level is
known.