J Clin Endocrinol Metab 42: 983, 1976
AMNIOTIC FLUID REACTIVITY DETECTED BY SOMATOMEDIN C RADIORECEPTOR ASSAY: CORRELATION WITH GROWTH HORMONE, PROLACTIN AND FETAL RENAL MATURATION R.H. Chochinov, A. Ketupanya, I.K. Mariz, L.E. Underwood, and W.H. Daughaday, Department of Medicine, Metabolism Division, Perinatal Unit, Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri 63110, and Department of Pediatrics, University of North Carolina, Chapel Hill, North Carolina 27514. ABSTRACT: Amniotic fluid was assayed by a radioreceptor assay utilizing somatomedin C and placental membranes. Growth hormone and prolactin levels were measured by radioimmunoassay at different gestational ages (8-41 weeks). Somatomedin receptor activity, growth hormone, and prolactin reached high levels during early gestation (8-26 weeks) displaying different patterns of appearance which reflect fetal serum levels of these hormones. After 26 weeks gestation all these hormones decreased in concentration. This decrease showed a strong correlation with fetal renal maturation as measured by amniotic fluid creatinine levels. Amniotic fluid contains varying amounts of glycoprotein and polypeptide hormones during different periods of gestation (1,2,3,4). The origin of these hormones and their relationship to fetal development is unclear. Therefore, in order to study these relationships, amniotic fluid somatomedin (Sm), growth hormone, and prolactin levels were measured at different gestational ages. The relationship between these peptide hormones in amniotic fluid and fetal renal maturation, as assessed by amniotic fluid creatinine levels, has been examined. SUBJECTS AND METHODS Amniotic fluid was obtained by standard amniocentesis techniques on 97 women for the usual indications. This yielded a total of 123 samples. The fluid was spun at 3 g for 10 minutes and the supernatant stored at -IOC until the time of analysis. Gestational age varied from 22-41 weeks. Diabetic patients were excluded from the study. An additional 93 samples were kindly supplied by Dr. Charles Faiman, University of Manitoba. Gestational age varied from 8-20 weeks. Details about their origin and dating have been previously reported (1). Therefore, a total of 216 specimens were analyzed. From the locally Submitted: February 2, 1976.
obtained amniotic fluid there were 71 samples with known gestational age as derived either from the last known menstrual period and/or measuring the fetal biparietal diameter by ultrasound. However, in order to standardize gestational age between the early and late samples, all dates are expressed as time from fertilization. Sm activity was measured by the radioreceptor assay of Marshall et al (5) using human placental membranes. The Sm activity is expressed in terms of figm of Ellis III standards, an impure preparation of 15 U/mgm dry weight or 66 jigm/U. Growth hormone and prolactin were measured by standard double antibody radioimmunoassay techniques in the Radioimmunoassay Laboratory of the Washington University Diabetes Center (6,7). Final dilutions of amniotic fluid gave displacement curves parallel to the standard curve in the SmC, GH, and Prl assays. For determination of SmC radioreceptor reactivity amniotic fluid was tested in a final concentration of 0.5%. For radioimmunoassay of GH concentrations of 2.5% or 0.5%, and for Prl 0.1% and 1% were utilized. Creatinine was measured by the method of Bonsnes et al (8). RESULTS The concentrations of SmC reactiv983
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 15 November 2015. at 21:26 For personal use only. No other uses without permission. . All rights reserved.
JCE & M • 1976 Vol 42 • No 5
RAPID COMMUNICATIONS
984
ity, GH, Prl versus gestational age are shown in Figure 1. In specimens of less than 12 weeks gestation, Sm was undetectable; after that, there was a rise in concentration which peaked at 17-20 weeks and slowly fell until term. Previously undetectable GH levels rose rapidly after 11 weeks, and, in contrast to Sm, peaked at 11-14 weeks, remained high until 25 weeks and then declined to low levels near term. Prl levels were low until 14 weeks, then they rapidly rose to peak at weeks 22-26. Thereafter, these levels rapidly declined to low levels near term. Although the pattern of rise in concentration of these hormones in amniotic fluid in early gestation (8-20 weeks) was different, after 26 weeks all these hormones decreased in concentration in a similar pattern reaching very low
TABLE 1: CORRELATION BETWEEN AMNIOTIC FLUID SOMATOMEDIN, GROWTH HORMONE AND PROLACTIN*
N
Hormone Somatomedin 0.46 Growth Hormone Somatomedin 0.66 Prolactin Growth Hormone 0.67
79
AMNIOTIC FLUID REACTIVITY DETECTED BY SOMATOMEDIN C RADIORECEPTOR ASSAY: CORRELATION WITH GROWTH HORMONE, PROLACTIN AND FETAL RENAL MATURATION R.H. Chochinov, A. Ketupanya, I.K. Mariz, L.E. Underwood, and W.H. Daughaday, Department of Medicine, Metabolism Division, Perinatal Unit, Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri 63110, and Department of Pediatrics, University of North Carolina, Chapel Hill, North Carolina 27514. ABSTRACT: Amniotic fluid was assayed by a radioreceptor assay utilizing somatomedin C and placental membranes. Growth hormone and prolactin levels were measured by radioimmunoassay at different gestational ages (8-41 weeks). Somatomedin receptor activity, growth hormone, and prolactin reached high levels during early gestation (8-26 weeks) displaying different patterns of appearance which reflect fetal serum levels of these hormones. After 26 weeks gestation all these hormones decreased in concentration. This decrease showed a strong correlation with fetal renal maturation as measured by amniotic fluid creatinine levels. Amniotic fluid contains varying amounts of glycoprotein and polypeptide hormones during different periods of gestation (1,2,3,4). The origin of these hormones and their relationship to fetal development is unclear. Therefore, in order to study these relationships, amniotic fluid somatomedin (Sm), growth hormone, and prolactin levels were measured at different gestational ages. The relationship between these peptide hormones in amniotic fluid and fetal renal maturation, as assessed by amniotic fluid creatinine levels, has been examined. SUBJECTS AND METHODS Amniotic fluid was obtained by standard amniocentesis techniques on 97 women for the usual indications. This yielded a total of 123 samples. The fluid was spun at 3 g for 10 minutes and the supernatant stored at -IOC until the time of analysis. Gestational age varied from 22-41 weeks. Diabetic patients were excluded from the study. An additional 93 samples were kindly supplied by Dr. Charles Faiman, University of Manitoba. Gestational age varied from 8-20 weeks. Details about their origin and dating have been previously reported (1). Therefore, a total of 216 specimens were analyzed. From the locally Submitted: February 2, 1976.
obtained amniotic fluid there were 71 samples with known gestational age as derived either from the last known menstrual period and/or measuring the fetal biparietal diameter by ultrasound. However, in order to standardize gestational age between the early and late samples, all dates are expressed as time from fertilization. Sm activity was measured by the radioreceptor assay of Marshall et al (5) using human placental membranes. The Sm activity is expressed in terms of figm of Ellis III standards, an impure preparation of 15 U/mgm dry weight or 66 jigm/U. Growth hormone and prolactin were measured by standard double antibody radioimmunoassay techniques in the Radioimmunoassay Laboratory of the Washington University Diabetes Center (6,7). Final dilutions of amniotic fluid gave displacement curves parallel to the standard curve in the SmC, GH, and Prl assays. For determination of SmC radioreceptor reactivity amniotic fluid was tested in a final concentration of 0.5%. For radioimmunoassay of GH concentrations of 2.5% or 0.5%, and for Prl 0.1% and 1% were utilized. Creatinine was measured by the method of Bonsnes et al (8). RESULTS The concentrations of SmC reactiv983
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 15 November 2015. at 21:26 For personal use only. No other uses without permission. . All rights reserved.
JCE & M • 1976 Vol 42 • No 5
RAPID COMMUNICATIONS
984
ity, GH, Prl versus gestational age are shown in Figure 1. In specimens of less than 12 weeks gestation, Sm was undetectable; after that, there was a rise in concentration which peaked at 17-20 weeks and slowly fell until term. Previously undetectable GH levels rose rapidly after 11 weeks, and, in contrast to Sm, peaked at 11-14 weeks, remained high until 25 weeks and then declined to low levels near term. Prl levels were low until 14 weeks, then they rapidly rose to peak at weeks 22-26. Thereafter, these levels rapidly declined to low levels near term. Although the pattern of rise in concentration of these hormones in amniotic fluid in early gestation (8-20 weeks) was different, after 26 weeks all these hormones decreased in concentration in a similar pattern reaching very low
TABLE 1: CORRELATION BETWEEN AMNIOTIC FLUID SOMATOMEDIN, GROWTH HORMONE AND PROLACTIN*
N
Hormone Somatomedin 0.46 Growth Hormone Somatomedin 0.66 Prolactin Growth Hormone 0.67
79
