MEASUREMENT OF EARLY CHORIONIC ACTIVITY WITH A RADIOIMMUNOASSAY SPECIFIC FOR HUMAN CHORIONIC GONADOTROPIN FOLLOWING SPONTANEOUS AND INDUCED OVULATION*

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1 Copyright 1974 The American Fertility Society FERTLTY AND STERLTY Vol. 25 No.3 March 1974 Printed in U.S.A. MEASUREMENT OF EARLY CHORONC ACTVTY WTH A RADOMMUNOASSAY SPECFC FOR HUMAN CHORONC GONADOTROPN FOLLOWNG SPONTANEOUS AND NDUCED OVULATON* THOMAS S. KOSASA M.D. C.M. LNDA A. LEVESQUE B.S. MELVN L. TAYMOR M.D. AND DONALD P. GOLDSTEN M.D. Department of Surgery (Gyn) Peter Bent Brigham Hospital and Harvard Medical School Boston Massachusetts Accurate measurement of early chorionic activity has been difficult since a practical method for distinguishing human chorionic gonadotropin (HCG) from human pituitary luteinizing hormone (HLH) has not been available. Reports of the measurement of HCG activity in very early pregnancy have been limited since conventional radioimmunoassays have not been able to specifically measure HCG activity without also measuring the activity of serum HLH being secreted by the pituitary gland.:t2 The recent development of a radioimmunoassay using antisera directed against the beta subunit of HCG3 has made it possible to accurately measure HCG activity without endogenous serum HLH interference. 4 5 This has permitted the accurate study of early chorionic activity following spontaneous and induced ovulation. MATERALS AND METHODS Patients Nine women were the subjects of this study. Two women with normal menstrual cycles and azoospermic husbands conceived following donor insemination and spontaneous ovulation. The day of ovulation was determined as precisely as pos- Received July Supported by U.S. Public Health Service Grant No. CA Presented in part at the Twenty Ninth Annual Meeting of the American Fertility Society April San Francisco California. 211 sible by the rise in serum HLH levels and by changes in the basal body temperature and cervical mucus. t has been shown that ovulation usually occurs on the day after the HLH peak. 6 One woman conceived after ovulation induced by 0 mg a day of clomiphene citrate (Clomid Merrell-National Laboratories Cincinnati Ohio) taken for 5 days from day 7 to day 11 of her cycle. Six women with anovulation conceived after human menopausal gonadotropin (HMG) (Pergonal Cutter Laboratories nc. Berkeley Calif.) was administered according to a previously described protocol. 7 An initial dose of 8000 U of HCG (A.P.L. Ayerst Laboratories New York NY) was followed 48 hours later by a second injection of 4000 U. Ovulation presumably occurred the day after the first HCG injection. Radioimmunoassays Human Chorionic Gonadotropin. We used antisera to the beta subunit of HCG (SB6) (provided by Drs. Judith Vaitukaitis and Griff T. Ross) which has a specificity for HCG.38 Highly purified HCG for use as an intermediate standard and for the purpose iodination was obtained from Serono Pharmaceuticals (Rome taly). One nanogram of this preparation is equivalent to 6.6 mili-u of the Second nternational Standard of HCG obtained from Dr. Derek Bangham World Health Organization.

2 212 KOSASA ET AL March 1974 Human chorionic gonadotropin was iodinated at room temperature by a modification of the method of Greenwood et al9 Two mci of low specific activity Na 125 (Amersham/Searle Chicago ll.) was added to 4"g of highly purified HCG dissolved in.025 ml of.4 M Na phosphate buffer (ph 7.5). Chloramine-T (.01 ml of a 25 mg/ ml solution of.01 M phosphate-buffered saline) was added to the hormone. Sodium metabisulfite (.025 ml of a 25 mg/ solution of.01 M phosphatebuffered saline) was used to stop the reaction after 2 minutes. The mixture was then added to a 5 by 0.5 cm column bed of Biogel P- (Bio Rad Labs Richmond Calif.) and collected in 0.5 ml aliquots. The specific activities of HCG ranged from 0 to 240 uci "g. Samples were assayed in duplicate in x 75 mm disposable glass tubes and the following reagents were added to make a final volume of 1.2 ml (All serum samples were added using lambda pipets): 1) Buffer containing.01m phosphate-buffered saline (PBS) % merthiolate and 1 % egg whites; 2) 0.2 ml of anti-hcg-b antisera (1: 0000 final dilution) in.05 M EDTA.01 M sodium phosphate 0.14 M sodium chloride ph 7.0 and 1:400 normal rabbit serum; 3) 0.2 ml of serum to be assayed or 0.2 of HCG standard in male sperm; 4) 0.1 ml of HCG125 containing 0.1 ng of hormone with counts ranging from 000 to cpm depending on the specific activity; and 5) 0.2 ml of sheep anti-rabbit gamma globulin (Antibodies ncorporated Davis Calif.). The previously described procedure used for this assay was: 1) Antisera iodinated hormone and the sample serum were added to buffer and incubated in a 37 C water bath for 2 hours. 2) After removal from the water bath the samples were incubated at 4 C for 2 hours. 3) The second antibody diluted in buffer (sheep anti-rabbit gamma globulin 1:64 initial dilution) was added and the mixture incubated for an additional 24 hours. 4) Tubes were centrifuged at 5000 rpm for minutes in a Sorvell RC-2 centrifuge and the supernatant aspirated by suction. 5) The precipitate was counted in a Nuclear-Chicago automatic well-type gamma counting system. Human Luteinizing Hormone. A double antibody radioimmunoassay was used to determine serum HLH concentrations in the patient being treated with clomiphene citrate and the two patients receiving donor insemination.1o odinated HCG was used as the tracer and the assays were carried out using a 48-hour incubation method.l1 Antisera to HCG generated in rabbits was used in the HLH assay at a final dilution of 1: The Second nternational Reference Preparation of HMG served as the standard for the HLH assays. Analysis of Radioimmunoassay Results. All radioimmunoassay data were analyzed with a computer program utilizing a curvilinear fitting of the quartic polynomial of the log dose.12 Statistical analysis was obtained by comparing the standard curves of consecutive assays and calculating their percentage variation. Each of the eight tubes in the standard curve ranging from 1.25 md ml to 165 md lmil was compared with its counterpart in the preceding assay and the percentage variation calculated. Six duplicate samples were included in every assay and were compared for their variation within the assay and also compared with their counterpart samples in the preceding assay. RESULTS The within-assay coefficient of variation for the HCG beta subunit assay used in this study ranged from 1 % to 4% and 1 1

3 Vol. 25 No.3 MEASUREMENT OF EARLY CHORONC ACTVTY 213 the between-assay coefficient of variation between 3 % and 8 % for the six replicate samples. Two patients receiving donor insemination conceived after spontaneous ovulation. A serum RCG level of 6 md /ml was first measured 8 days following probable ovulation -in one patient and a level of 11 md/ml was measured 11 days after ovulation in the other (Figs. 1 and 2). n the first patient the RCG doubling 0 miu/11 hce blh 1- \ \ \ \ \ \.. ""'----. / Ol~~~~~~~~~~~_ 5.7 e 11 Z~141S1617 \8"202222~~ ~20 ::! E _ kec lh ~ " ' '; 1 " ~ l ) ~=::? S " ~25218 ~ ~ NSEMNAl ON DAY OF CYCLE FG. 2. Serum human chorionic gonadotropin (HCG) and human pituitary luteinizing (HLH) levels in second patient who received donor insemination and conceived after spontaneous ovulation. '-1 --( t! '" c 8 '2 '" 18 e t t NSfM.N f8 e ' ~ ~ NSfMNA TlON DAY OF CYClE FG. i. Serum human chorionic gonadotropin (HCG) and human pituitary luteinizing hormone (HLH) levels in first patient who received donor insemination and conceived after spontaneous ovulation. time was 1.8 days; in the second patient it was 1.7 days (Table 1). One patient conceived after recevmg clomiphene citrate. A rise in her RLR and shift in basal body temperature occurred 9 days after she finished her medication. A serum RCG level of 16.8 md/ ml was measured days after her RLR rise or 9 days after probable ovulation (Fig. 3). Six patients conceived after treatment with RMG/RCG. n three of the patients ReG levels fell to zero within 5 to 8 days following the last administration of RCG. The reappearance of RCG representing chorionic activity could be detected on days 11 and 14 follow- TABLE i.-nitial Measurement of HCG Following Probable Ovulation and Doubling Time of HCG Following mplantation Patient nitial measurement of chorionic activity (days after ovulation) Doubling time ofhcg (days) 1. Spontaneous ovulation Spontaneous ovulation Clomiphene therapy HMG/HCG therapy HMG/HCG therapy HMG/HCG therapy HMG/HCGtherapy HMG/HCG therapy HMG/HCG therapy

4 214 KOSASA ET AL March ~30 "" ~ :po ;1 E hcs lh /' / / J \ \ \ \ c ~ bcg [ 7 9 /3 /5 /7 19 2/ H~H CLOMPMEE ~98 L\ ~- ca97>~~~~q::== S DAY OF CYCLE FG. 3. Serum human chorionic gonadotropin (RCG) and human pituitary luteinizing hormone (RLR) levels in patient who conceived after treatment with clomiphene citrate. ing presumed ovulation (Fig. 4). The RCG doubling times of these patients were and 1.9 days respectively. n three other patients conceiving after 0 bcg." & ~ ~ ~ ~ DAYS FO OV LATiOM HG hc; FG. 5. Serum human chorionic gonadotropin (RCG) levels in three patients conceiving after human menopausal and human chorionic gonadotropin (RMG/RCG) therapy whose RCG levels never disappeared. completely following treatment but began to rise in response to chorionic activity. RMG/RCG therapy the RCG levels never disappeared completely following administration of RCG. One week after the last administration of RCG 14 md /ml 26 md/ml and 31.5 md/ml of RCG could be measured in their serum (Fig. 5). n two patients RCG fell to 11 and 11.5 md /ml by day 11 and began to rise again by day 14. The serum RCG of the third patient fell to 17.5 md/ml on day 12 and by day 15 had risen to over 0 md/ml. The RCG doubling times of these patients were and 1.9 days. MG & DAYS F80M OVULATON hcc FG. 4. Serum human chorionic gonadotropin (RCG) levels in three patients who conceived after human menopausal and human chorionic gonadotropin (RMG/HCG) therapy. DSCUSSON The development of a sensitive radioimmunoassay specific for RCG has made it possible to detect the first signs of chorionic activity and to measure the rate of development of the trophoblast. Other studies have shown that pregnancies resulting from induced ovulation have proceeded normally. The patterns of RCG secretion and the normal outcome of these

5 Vol. 25 No.3 MEASUREMENT OF EARLY CHORONC ACTVTY 215. ~ ~ pregnancies have supported the assumption that these pregnancies were not measurably different from those resulting from spontaneous ovulation'12 One of the purposes of this study was to compare implantation and early trophoblastic development after spontaneous and induced ovulation. The initial detection and pattern of HCG secretion were studied to find any measurable differences between spontaneous and induced ovulation. Among the nine patients studied two conceived after spontaneous ovulation and seven conceived after ovulation induction. Human chorionic gonadotropin was first detected 8 and 11 days following presumed ovulation in the patients ovulating spontaneously. The detection of HCG in the patients conceiving after induced ovulation ranged from to 15 days. No delayed rise in HCG was observed in the group of patients receiving HMG/HCG therapy although this phenomenon has been previously reported.2 The doubling times of HCG in the patients ovulating spontaneously were 1.8 and 1.7 days; this was not significantly different from the range of 1.4 to 2.1 days in the patients conceiving after ovulation induction. The similarity between the initial time of detection of HCG and the subsequent pattern of HCG secretion in pregnancies following either spontaneous or induced ovulation has been observed by others.4 t appears from this study that probably there is no significant difference between implantation and early chorionic activity following induced and spontaneous ovulation. SUMMARY Serum HCG was measured by a radioimmunoassay specific for the beta subunit of HCGin nine patients who conceived after either spontaneous or induced ovulation. Two patients conceived following donor insemination and spontaneous ovulation. One patient conceived after ovulation induced by clomiphene citrate and six patients conceived after HMG/HCG therapy. Serum HCG was first detected 8 and 11 days after presumed ovulation in the two patients who conceived following spontaneous ovulation and donor insemination. Serum HCG was measured 9 days after presumed ovulation in one patient treated with clomiphene citrate and to 15 days after presumed ovulation in six patients receiving HMG/HCG therapy. The doubling times of HCG were measured from 40 mu/ml to 80 mu /ml. Following spontaneous ovulation the doubling times were 1.8 and 1.7 days while the doubling times following induced ovulation ranged from 1.4 to 2.1 days. There appeared to be no significant difference between the initial time of detection of HCG after spontaneous or induced ovulation. There also appeared to be no appreciable difference in the pattern of rising serum HCG levels following spontaneous or induced ovulation. Acknowledgments. The authors wish to express their thanks for the technical assistance provided by William Byer William Donn Rogosin Stephen Kirsch Susan Griffin and Nicholas ula. REFERENCES 1. Marshall JR Hammond CB Ross GT et al:.plasma and urinary chorionic gonadotropin during early human pregnancy. Obstet Gynecol 32: Goldstein DP Miyata J Taymor ML et al: A rapid solidphase radioimmunoassay for the measurement of serum luteinizing hormone-human chorionic gonadotropin (LH HCG) activity in very early pregnancy. Fertil Steril 23: Vaitukaitis JL Braustein GD Ross GT: A radioimmunoassay which specifically measures human chorionic gonadotropin in the presence of human luteinizing hormone. Am J Obstet Gynecol 113:

6 216 KOSASA ET AL March Braunstein GD Grodin JM Vaitukaitis J et al: Secretory rates of human chorionic gonadotropin by normal trophoblast. Am J Obstet Gynecol 115: Kosasa TS Levesque LA Goldstein DP et al: Early detection of implantation using a radioimmunoassay specific for human chorionic gonadotropin. J Clin Endocrinol Metab 36: Yussman MA Taymor ML: Serum levels of follicle stimulating hormone and luteinizing hormone and of plasma progesterone related to ovulation by corpus luteum biopsy. J Clin Endocrinol Metab 30: Taymor ML: nduction of ovulation with human menopausal gonadotropin. n Progress in Gynecology. Vol. V. Edited by SH Sturgis and ML Taymor. New York Grune & Stratton 1970 p Vaitukaitis JL Ross GT: Antigenic similarities among the human glycoprotein hormones and their subunits. n Gonadotropins. Edited by B Saxena H Gandy and C Beling. New York John Wiley & Sons 1972 p Greenwood FC Hunter WM Grover JS: The preparation of131-labeled human growth hormone of high specific radioactivity. Biochem J 89: Aono T Goldstein DP Taymor ML et al: A radioimmunoassay method for human pituitary luteininzing hormone (LH) and human chorionic gonadotropin (HCG) using 125-abeled LH. Am J Obstet Gynecol 0: KosasaTS Thompson E Byer WB: A comparison between gonadotropin radioimmunoassays employing 48 hour and 6 day incubation methods. (Unpublished data) 12. Lee EY Kosasa TS: Computer analysis of radioimmunoassay data. (Unpublished data)