Human Placental Lactogen Levels Research Articles

Glucose-insulin interaction and the modulation of human placental lactogen (HPL) secretion during pregnancy.

SummaryIn order to define metabolic factors which control human placental lactogen (HPL) secretion two types of experiment have been conducted: (a) hypoglycaemia was induced by intravenously‐injected insulin in 21 normal women in late pregnancy; and (b) a sustained hyperglycaemia was obtained by glucose infusion in six normal women in late pregnancy. Serum HPL was determined using an immunosorbent antibody radioimmunoassay procedure. Blood glucose was estimated in both experiments and plasma immunoreactive insulin in the second. The results show an inverse relationship between blood glucose and serum HPL concentrations. Hyperglycaemia caused the HPL level to fall and conversely insulin‐induced hypoglycaemia caused it to rise. Moreover, declining blood glucose levels after the cessation of a glucose infusion were accompanied by an increase in HPL comparable to that seen during frank hypoglycaemia.

Human placental lactogen levels in the serum during early pregnancy.

HPL is a proteohormone produced by the placenta. The radio-immunological determination is presently used mainly for supervision during late pregnancy. There is no agreement regarding the diagnostic or prognostic significance of HPL during the first half of pregnancy. This may be due to the modification of the method of determination established for late pregnancy necessary for a determination during early pregnancy. The small number of results so far obtained from examinations during early pregnancy may also partly be responsible. For this reason we decided to Start by fixing the HPL range for normal early pregnancies on the basis of accurately defined groups of pregnant women and then to check whether deviating HPL values are to be found in women with uterine hemorrhage during the first half of pregnancy.

Human placental lactogen (HPL) in serum in complicated early pregnancy.

SummaryThe clinical value of maternal serum HPL concentrations determined by radio‐immunoassay in complicated early pregnancy was studied between the 6th and 20th weeks of pregnancy. The subjects were 203 normally pregnant women and 188 whose pregnancy was complicated by uterine bleeding. In threatened abortion where the pregnancy continued successfully (102 patients) the HPL level was generally similar to that in normal pregnancy and showed a pattern of increase in serial determinations. In complicated pregnancies with an unsuccessful outcome (blighted ovum 19, incomplete abortion 42, and missed abortion 25) HPL values were low and decreased in serial samples. A single HPL determination seemed to be a sufficiently reliable index of viable pregnancy from the 14th week onwards, but before that serial HPL samples would seem to be needed.

Human placental lactogen (HPL) levels in maternal serum during abortion induced by intra- and extra-amniotic injection of prostaglandin F2a.

SummaryHuman placental lactogen (HPL) concentrations in maternal serum were measured by double antibody radioimmunoassay in 25 patients who were undergoing abortion by intra‐ and extra‐amniotic injection of prostaglandin F2α (PGF2α) and by extra‐amniotic injection of hypertonic saline in the first and second trimesters of pregnancy. The injection of 150 ml. of 20 per cent NaCl did not change the HPL level but the extra‐amniotic injection of 5 to 6 mg. of PGF2α and the intra‐amniotic injection of 20 to 25 mg. of PGF2α decreased the serum HPL level significantly (p<0.01) in the two hours after the injections. PGF2α administered by intrauterine routes appeared to have a direct effect on the placental synthesis and/or the secretion of HPL in early pregnancy.

Alpha fetoprotein and human placental lactogen levels in maternal serum in multiple pregnancies.

SummaryAlpha fetoprotein (AFP) and human placental lactogen (HPL) concentrations were measured in maternal serum by radioimmunoassay. Compared with normal single pregnancies, both AFP and HPL concentrations were elevated in multiple pregnancies. Among twin pregnancies, AFP levels exceeding the normal 97.5th centile were associated with intrauterine fetal death in 4 of 7 cases, while fetal death occurred in only 1 of 12 where the maternal AFP concentration was normal. HPL levels in twin pregnancies were below the normal median if the fetus died in utero. The combined efficacy of both AFP and HPL levels in the monitoring of twin pregnancies was assessed. The efficacy of either marker was increased by the concomitant application of the other.

Hormone and enzyme levels in normal and complicated pregnancy

A retrospective study of 48 high-risk pregnancies has been made. The values of two hormonal and two enzyme assays have been compared in assessing placental function. Neither of the enzyme levels (serum heat-stable alkaline phosphatase and serum diamine oxidase) were found to be of clinical value. Serum human placental lactogen levels were consistently decreased in essential hypertension and in pregnancies terminating in stillbirth. Urinary estriol estimation proved to be more reliable, especially in monitoring the “light-for-dates baby” pregnancies and those pregnancies associated with perinatal death.

Variations in maternal plasma levels of human placental lactogen (HPL) in normal pregnancy and labour.

SummaryPlasma levels of human placental lactogen (HPL) in normal pregnancy from the 22nd week until delivery were measured with a rapid radioimmunoassay. The HPL concentration in plasma rose steadily up to the 37th week and thereafter gradually decreased until delivery. Individual women followed during the latter part of pregnancy showed a characteristic pattern with very small deviations from their original relative level within the normal range.Significant fluctuations in HPL levels were noted during a 24‐hour period of sampling and during shorter periods. No systematic circadian variation was observed. The variations showed no clear relation to sleep, meals or light exercise. During spontaneous and induced labour significant fluctuations in HPL concentrations occurred but these were of the same magnitude as those during the latter part of normal pregnancy; no correlation between HPL levels and uterine contraction and relaxation was found.Strenuous physical exercise during the last month of pregnancy sufficient to affect the fetal heart rate did not influence the HPL levels.

The effect of posture on serum human placental lactogen (HPL) levels in normal and complicated late pregnancy.

SummarySerum HPL levels were determined in the supine and upright positions at two‐hour intervals in normal and complicated late pregnancies. No significant difference could be demonstrated.

Circulating levels of human placental lactogen in late pregnancy: the effect of glucose loading, smoking and exercise

Abstract Plasma levels of human placental lactogen have been determined in a number of experimental situations. Oral glucose loading produced no change in levels, while an intravenous glucose load produced a consistent fall. Heavy smoking and vigorous exercise resulted in alterations in placental lactogen levels in some, but not in all subjects.

Human placental lactogen levels and intrapartum fetal distress: Meconium-stained amniotic fluid, fetal heart rate patterns, and Apgar scores

Serum human placental lactogen (HPL) levels were serially determined by a solid-phase radioimmunoassay technique. A total of 1,595 samples were obtained on 1,100 women with high-risk pregnancies. The infants were monitored during labor for signs of intrapartum distress. There was no relationship found between the HPL levels and the fetal heart rate patterns recorded during more than 400 hours of labor by continuous invasive electronic techniques. There was also no relationship between the HPL levels and the 5 minute neonatal Apgar score. There was a positive and significant correlation between the level of HPL one day before labor and the one-minute Apgar score. In addition, there were significantly more lower HPL values found in those pregnancies with meconium-stained amniotic fluid and a vertex presentation. These results suggest that HPL may be clinically useful as a placental function test but also that it cannot be the only tool used for the selection of patients for intrapartum biophysical fetal monitoring.

Human placental lactogen levels in pre-eclampsia.

SummaryA prospective study has been carried out on human placental lactogen (HPL) levels in pre‐eclampsia. The general conclusions were as follows: (1) the levels were lower than those in normal subjects; (2) the levels in mild pre‐eclampsia were lower than those in the moderate and severe cases; (3) the levels were lower in multipara than in primipara. The influence of severity and parity may partly explain the discrepancies encountered in earlier studies. Low levels of HPL were found in patients with fetal complications. However, since similar levels may be found in pre‐eclampsia without such complications, it was not possible to reach definite conclusions on the value of HPL determinations as a predictor of fetal well‐being. The results indicate the need for further investigation of the prognostic significance of HPL levels within sub‐groups of patients with pre‐eclampsia.

The degradation of human placental lactogen in normal and nephrectomized dogs.

SUMMARY To determine the site of degradation of human placental lactogen (HPL) the disappearance rate of 125I-labelled and unlabelled HPL was studied in intact normal and nephrectomized dogs. Methods for determining plasma levels of 125I-labelled HPL included measurement of total radioactivities, radioactivities after trichloroacetic acid precipitation and immunoprecipitation, and chromatoelectrophoresis. Plasma HPL levels were determined by a radioimmunoassay method. In the dog, of the several organs studied, only the kidney was found to be involved in the degradation of both labelled and unlabelled hormone. The role of the kidney in the degradation of polypeptide hormones is discussed.

PATTERNS OF SERUM IMMUNOREACTIVE HUMAN PLACENTAL LACTOGEN (IR-HPL) AND CHORIONIC GONADOTROPIN (IR-HCG) IN DIABETIC PREGNANCY

Serum levels of immunoreactive human placental lactogen (IR-HPL) and chorionic gonadotropin (IR-HCG) were evaluated in eighty-four diabetic patients classified according to White. All patients in this group were treated with estrogen/progesterone therapy throughout pregnancy and were compared with a small group of twenty-seven diabetic patients not receiving hormonal therapy. In 164 normal pregnancies, serum IR-HPL is detected first at about six weeks and rises steadily to plateau levels of 6.2 ± 1.4 μg./ml. at thirty-five to thirty-seven weeks. In eighty-four diabetic pregnancies, the pattern of steady rise in IR-HPL levels simulates normal but the mean values are significantly greater than normal with peak values of 10.3 ± 4.7 /μg./ml. at thirty-five to thirty-seven weeks. Serum IR-HCG is first measured in normal pregnancy at about five to seven weeks by this assay, rises rapidly to peak levels of 163 ± 60 IU./ml. at eight to ten weeks and then falls to a nadir of 12.0 ± 2.0 IU./ml. at seventeen to nineteen weeks. Thereafter, there is a gradual secondary rise to a lesser mean peak value of 63 ± 19 IU./ml. at thirty-five to thirty-nine weeks. In diabetic pregnancy, the pattern of serum IR-HCG is similar to normal but with striking quantitative differences. The mean values in the second and third trimesters are significantly higher than normal with extreme variations among different pregnant individuals. The clinical implications of these abnormalities are not clear but suggest that the excessive secretion of HCG may mollify the diabetic imposition of early pregnancy whereas HPL contributes to the exaggerated glucose intolerance in late pregnancy.

Patterns of serum immunoreactive human placental lactogen (IR-HPL) and chorionic gonadotropin (IR-HCG) in diabetic pregnancy.

Serum levels of immunoreactive human placental lactogen (IR-HPL) and chorionic gonadotropin (IR-HCG) were evaluated in eighty-four diabetic patients classified according to White. All patients in this group were treated with estrogen/progesterone therapy throughout pregnancy and were compared with a small group of twenty-seven diabetic patients not receiving hormonal therapy. In 164 normal pregnancies, serum IR-HPL is detected first at about six weeks and rises steadily to plateau levels of 6.2 ± 1.4 μg./ml. at thirty-five to thirty-seven weeks. In eighty-four diabetic pregnancies, the pattern of steady rise in IR-HPL levels simulates normal but the mean values are significantly greater than normal with peak values of 10.3 ± 4.7 /μg./ml. at thirty-five to thirty-seven weeks. Serum IR-HCG is first measured in normal pregnancy at about five to seven weeks by this assay, rises rapidly to peak levels of 163 ± 60 IU./ml. at eight to ten weeks and then falls to a nadir of 12.0 ± 2.0 IU./ml. at seventeen to nineteen weeks. Thereafter, there is a gradual secondary rise to a lesser mean peak value of 63 ± 19 IU./ml. at thirty-five to thirty-nine weeks. In diabetic pregnancy, the pattern of serum IR-HCG is similar to normal but with striking quantitative differences. The mean values in the second and third trimesters are significantly higher than normal with extreme variations among different pregnant individuals. The clinical implications of these abnormalities are not clear but suggest that the excessive secretion of HCG may mollify the diabetic imposition of early pregnancy whereas HPL contributes to the exaggerated glucose intolerance in late pregnancy.

Serum placental lactogen activity in patients with molar pregnancy and trophoblastic tumors—A reliable index of malignancy

Serum human placental lactogen (HPL) activity has been measured in patients with molar pregnancy and trophoblastic tumors of gestational and nongestational origin. The serum HPL activity of patients with molar pregnancy was related to the histologic grading of the tumor and gestational age and did not correlate with the metabolic activity of the trophoblastic tissue as reflected in the HCG titer. The greater the degree of malignancy, the lower the HPL level. Furthermore, malignant trophoblastic tissue appears to have similar HPL-reducing activity regardless of its origin, gestational or nongestational. This observation may form the basis for a useful tool in predicting the neoplastic potential of an hydatidiform mole. The half-life of HPL produced by molar pregnancy appears to be larger than that reported for normal pregnancy at term.

Plasma human placental lactogen in late pregnancy and labor

Human placental lactogen (HPL) is a polypeptide placental hormone secreted in increasing amounts during pregnancy with both prolactin- and growth hormone-like properties. Development of a radioimmunoassay system for this hormone has allowed the authors to follow patients in late pregnancy and labor. When subjected to statistical analysis, the mean plasma HPL levels obtained showed a significant fall when the 40 week specimen is compared to those obtained in late labor. These data indicate that a change in HPL is not involved in the process of the initiation of labor. The observed change in HPL, however, reflects the relative uterine and placental ischemia of labor. The potential use of HPL as an index of placental function is discussed.

Measurement of human placental lactogen by microcomplement fixation: Comparison with radioimmunoassay

A microcomplement fixation method (MCF) is described for the measurement of human placental lactogen (HPL) in maternal pregnancy serum and compared with the radioimmunoassay method (RIA) in 58 women in various stages of pregnancy. MCF is not yet sensitive enough to detect HPL levels before the twelfth week of pregnancy, but thereafter the results are closely comparable by both methods. MCF is less costly and no more time-consuming than RIA and it avoids the possibility of altering the antigen by radioactive labeling. It does require strict attention to environmental conditions, but, nevertheless, should be more easily available for use in routine hospital laboratories and facilitate, thereby, the assessment of the true value of HPL in obstetric management.

Immunoassay of HPL by complement fixation.

A method for quantitative assay of human placental lactogen (HPL) utilizing micro-and normal complement fixation has been developed. This method has excellent reproducibility as well as sensitivity. The sensitivity for HPL is 6ng/ml of the 90% pure Lederle preparation. The standard curve for HPL is linear between 6 and 40 ng/ml. This specific method of assay has been utilized to determine the level of HPL in 0.1 ml pregnancy serum. The results of this inexpensive, sensitive and specific method of assay of HPL are available within 24 hours. Thus this method can be utilized in clinical laboratories if assay of HPL proves to be of clinical use.

SERUM PLACENTAL LACTOGEN LEVELS DURING PREGNANCY AND IN TROPHOBLASTIC DISEASE

A quantitative radioimmunoassay for human placental lactogen (HPL) in serum is described utilizing a highly purified preparation of HPL. HPL was detected in the serum of pregnant women as early as the sixth week of gestation and the levels rose steadily during the first and second trimesters, reaching a plateau during the third trimester. Serum HPL levels show little variation during the day and are not affected by induced hypoglycemia or hyperglycemia. HPL disappears promptly from the blood after delivery with a half-life in serum of approximately 30 min. Relatively small quantities of HPL were detectable in umbilical cord blood, indicating only a minor transplacental transfer of this protein. HPL was measured in the serum of 6 patients with trophoblastic tumors, and the levels were comparable to those of early pregnancy or lower.

Human placental lactogen levels as a measure of placental function

Human placental lactogen levels as a measure of placental function