Human Chorionic Somatomammotropin : hCS (Human Placental Lactogen : hPL) and Estriol Secretion in Abnormal Pregnancy

Abstract

In regard to its biological and immunological characteristics, human chorionic somatomammotropin, otherwise known as human placental lactogen, can be found in its activity as a metabolism regulating hormone during pregnancy. This hCS is produced with a fairly rapid speed in the placenta and is secreted constantly with fairly great reserve. At the same time, its half life is so short that the serum hCS concentration sensitively changes according to the condition at the site of its production.
Therefore the clinical value of systematic measurement of hCS appears to be parameter of the function of placenta and indirectly, fetal growth and maturity.
On the other hand, estriol synthesis begins in the fetal adrenal with production of dehydroepiandrosterone (DHA), the major precursor of urinary estriol. Further metabolism includes 16-α hydroxylation which is performed largely in the fetal liver, and the formation of free estriol from 16-α OH-DHA which takes place in the placenta. So, it is considered that urinary estriol represents the function of feto-placental unit.
Therefore, to understand the clinical usefullness for monitoring the placental and feto-placental function, serum hCS and urinary estriol were measured with systematic serial estimation in comparison with the secretory behavior of these two hormones.
Furthermore, DHA-S dynamic test was performed to evaluate the feto-placental function.
HCS was measured by double antibodies radioimmunoassay and estriol was detected by the modified method of Brown's.
Summarized deta are as follow.
In the cases of normal pregnancy, serum hCS could be detected in the 8th week of gestation (0.02 μg/ml) and serum hCS concentrations showed a pattern of gradual increase reaching a plateau at about the 36th week of gestation (4-10 μg/ml).
Urinary estriol concentration at the 12th week of gestation was 0.5 mg/day and its secretion pattern also showed gradual increase according to the progress of the pregnancy.Urinary estiol level at the term was 10-30 mg/day.
In threatened abortion which terminated in the complete abortion, both estriol and hCS were low, or lowered even though they were in normal range at the beginning.
In the cases of intrauterine fetal death, both hormones were markedly low.
In the pregnancies with anencephalus, only estriol was low. On the contrary, hCS was low in a case of placental insufficiency.
In severe cases of sensitized rhesus incompatibility, estriol was abruptly lowered at the end of the pregnancy, but hCS was in normal range.
In the cases of SFD, hCS levels did not show any increasing pattern from the 28th week to term, but estriol levels were normal.
In the cases of severe toxamia of pregnancy, both hCS and estriol were lowered at the end of the pregnancy.
In the cases of pregnancy complicated with diabetes mellitus or prolonged pregnancy, both hormones were in the normal range.
To illustrate the correlation of these two hormones in the abnormal pregnancy, urinary estriol levels were plotted on the vertical axis and serum hCS was plotted on the horizontal axis. Low estriol zone and low hCS zone were determined and shadowed by drawing a line at the lowest levels of 95 % confidence limit of these hormones in the normal pregnancy. The area on which two shadowed area are superimposed was named as absolutely abnormal zone.
In threatened abortion which terminated in complete abortion, “the point” showing the two hormone levels was plotted in the absolutely abnormal zone from the onset of symptom or the point moved into there during the progress of clinical picture. In the cases of intrauterine fetal death, “the point” was in the absolutely abnormal zone. In the cases of anencephalus, “the point” was in the low estriol zone. In the cases of sensitized rhesus incompatibility,