0021-972X/91/7205-1042$03.00/0 Journal of Clinical Endocrinology and Metabolism Copyright © 1991 by The Endocrine Society
Vol. 72, No. 5 Printed in U.S.A.
The Effect of Human Chorionic Gonadotropin and Pregnancy on the Circulating Level of Relaxin MARK R. JOHNSON*, ELIZABETH OKOKON, WILLIAM P. COLLINS, VINAY SHARMA, AND STAFFORD L. LIGHTMAN Neuroendocrinology Unit, Charing Cross and Westminster Medical School, Charing Cross Hospital, London, W6 8RF United Kingdom; the Department of Obstetrics and Gynecology, King's College School of Medicine and Dentistry (E.O., W.P.C., V.S.), Denmark Hill, London, SE5 8RX United Kingdom
ABSTRACT. The effect of hCG and pregnancy on the circulating levels of relaxin was investigated in 48 women undergoing in vitro fertilization and embryo transfer (ET) for the treatment of infertility. Subjects were allocated randomly to receive hCG (Profasi; 2000 IU, im) or placebo on the day of ET (day 0) and on day 3 after ET (day 3). Samples of peripheral blood were taken on days —4, 6, and 10. An additional sample was taken on day 22 from women who became pregnant. The subjects were allocated retrospectively to 1 of 4 groups: no pregnancy, no hCG (NP); pregnancy, no hCG (P); no pregnancy, hCG (NPH); and pregnancy, hCG (PH). Two patients with blighted ova and one with a tubal pregnancy were excluded from the analysis. The concentrations of relaxin were similar and rose significantly in all groups at each time point (P < 0.05). On day 6 there was no significant difference in the increment between the groups, but by day 10, circulating levels in the P compared to the NP and those in the PH compared to the NPH group were significantly greater (P < 0.05). By day 22 the difference between
the PH and the P groups was significant (P < 0.05). Relaxin levels correlated with progesterone levels on day 10 in the NP and P groups (r = 0.633; P < 0.05 and r = 0.697; P < 0.05, respectively) and with estradiol levels in the P group only on days 6 and 22 (r = 0.659; P < 0.05 and r = 0.783; P < 0.05, respectively). These data demonstrate that in women undergoing in vitro fertilization, relaxin levels increase during the luteal phase, and in those women who establish a pregnancy, the values are significantly greater by day 10. The administration of hCG in the early luteal phase, before implantation, to women who subsequently become pregnant significantly increased the level of circulating relaxin on day 22. The positive correlation between relaxin levels and ovarian steroid levels in the groups not receiving exogenous hCG suggests that a common factor may control the release of both. (J Clin Endocrinol Metab 72: 1042-1047, 1991)
R
ELAXIN can first be detected in peripheral plasma 6 days after the midcycle surge of LH; 4 days later, the concentration is significantly higher if conception has occurred (1). During pregnancy, the level of serum relaxin, as measured by a homologous RIA, is highest by the 10th week, at about 900 pg/mL, it then falls to a plateau of about 500 pg/mL for the remainder of the pregnancy (2); in contrast to pigs and rats (3, 4), there is no evidence in man for a prepartum surge in relaxin levels (5). The similarity in the patterns of serum relaxin and hCG levels throughout pregnancy (2) suggests that a causal relationship may exist between the two. This possibility is supported by the observation that exogenous hCG stimulates the release of relaxin in women Received September 24, 1990. Address all correspondence and requests for reprints to: Dr. Mark R. Johnson, Neuroendocrinology Unit, Charing Cross and Westminster Medical School, Charing Cross Hospital, Fulham Palace Rd, London W6 8RF United Kingdom. * Supported by a Williams Fellowship from London University and recipient of a Joint Research Committee grant from the Trustees of the Westminster Hospital Group.
during the late luteal phase (6). We have undertaken a systematic study to determine the extent to which hCG and pregnancy may affect the release of relaxin and other ovarian hormones around the periimplantation period in infertile women who are being treated by in vitro fertilization (IVF) and embryo transfer (ET).
Subjects and Methods Subjects Forty-eight patients undergoing IVF who were under 38 yr of age and had tubal damage only as a cause of their infertility were entered in the study. All subjects received clomiphene citrate (Clomid, Merrel Dow Pharmaceuticals Ltd., Uxbridge, Middlesex, United Kingdom; 100 mg, orally) on days 2-6 of their menstrual cycle, human menopausal gonadotropin (Pergonal, Serono Laboratories, Welwyn Garden City, Herts, United Kingdom; two to six ampoules per day, im, depending on previous responses) was started on days 2-4 (depending on the length of the normal cycle) and continued until the leading follicle reached a mean diameter of 17 mm and at least three follicles greater than 14 mm were present. hCG (Profasi, Ser-
1042
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 23 November 2015. at 01:44 For personal use only. No other uses without permission. . All rights reserved.
EFFECT OF hCG AND PREGNANCY ON RELAXIN
1043
TABLE 1. The concentrations of plasma hormones [geometric mean and range (in parentheses)] before and after ET in women undergoing IVF (14 with and 12 without hCG luteal phase support) who did not become pregnant Day relative to ET -4
+
-
Luteal support: Relaxin (pg/mL)
30 (32-42) 16 (4-65) 4587 (2164-7879)
Progesterone (nmol/L) Estradiol (pmol/L)
10
6
+
47" (27-87) 103° (53-220) 19936 (890-6645)
28 (20-94) 16 (3-34) 4357 (2486-5599)
+
6
51 (22-103) 12 (3-45) 3976 (89-1295)
70° (23-212) 248° (120-550) 3206h (1580-9795)
71 6 (20-310) 17 (6-132) 675" (300-4485)
° P < 0 . 0 1 us. basal value. 6 P < 0.05 us. basal value. TABLE 2. The concentrations of plasma hormones before and after ET in women undergoing IVF (8 with and 12 without hCG luteal phase support) who became pregnant Day relative to ET -4
Progesterone (nmol/L) Estradiol (pmol/L)
22
10
-
+
-
+
-
+
-
+
28 (20-61) 16 (3-58) 5046 (2936-11316)
25 (20-50) 8.5 (3-23) 5267 (3449-7364)
54" (28-100) 95b (40-210) 2323* (1545-3470)
110° (30-624) 284° (158-690) 4726 (1700-12945)
4726 (180-1181) 1646 38-425) 20246 (475-3770)
791° (241-1923) 270° (138-645) 5679 (2230-14855)
2194° (1136-4682) 1806 (46-325) 4139 (1260-9795)
6052° (2705-12333) 290" (110-735) 8627 (3695-34735)
Luteal support: Relaxin (pg/mL)
6
° P < 0.05 vs. basal value. P < 0.01 vs. basal value.
b
ono, Welwyn Garden City, Herts, United Kingdom; 5000 IU, im) was administered, and oocytes were collected 34-38 h later. Two days later, two or three embryos were transferred to the uterus. Subjects were allocated randomly to receive hCG (2000 IU, im) or placebo on the day of ET (day 0) and on day 3. Blood samples were taken on days —4, 6, and 10, and on day 22 in subjects who became pregnant. Blood was taken into lithium-heparin tubes, and the plasma was separated by centrifugation and stored at —20 C before analysis. Pregnancy was defined as a positive immunochemical pregnancy test (hCG, >25 U/L) 14 days after ET and was confirmed by the presence of a gestational sac (as observed by transvaginal ultrasonography 7 days later). The protocol was approved by the Ethics Committee of King's College Hospital. Methods The concentration of relaxin was measured in unextracted plasma by a noncompetitive enzyme-labeled immunoassay (7). The standards, from 20-1250 pg/mL, were prepared in pooled normal male plasma. The working range of the assay (defined as the lowest and the highest value with a coefficient of variation of
Vol. 72, No. 5 Printed in U.S.A.
The Effect of Human Chorionic Gonadotropin and Pregnancy on the Circulating Level of Relaxin MARK R. JOHNSON*, ELIZABETH OKOKON, WILLIAM P. COLLINS, VINAY SHARMA, AND STAFFORD L. LIGHTMAN Neuroendocrinology Unit, Charing Cross and Westminster Medical School, Charing Cross Hospital, London, W6 8RF United Kingdom; the Department of Obstetrics and Gynecology, King's College School of Medicine and Dentistry (E.O., W.P.C., V.S.), Denmark Hill, London, SE5 8RX United Kingdom
ABSTRACT. The effect of hCG and pregnancy on the circulating levels of relaxin was investigated in 48 women undergoing in vitro fertilization and embryo transfer (ET) for the treatment of infertility. Subjects were allocated randomly to receive hCG (Profasi; 2000 IU, im) or placebo on the day of ET (day 0) and on day 3 after ET (day 3). Samples of peripheral blood were taken on days —4, 6, and 10. An additional sample was taken on day 22 from women who became pregnant. The subjects were allocated retrospectively to 1 of 4 groups: no pregnancy, no hCG (NP); pregnancy, no hCG (P); no pregnancy, hCG (NPH); and pregnancy, hCG (PH). Two patients with blighted ova and one with a tubal pregnancy were excluded from the analysis. The concentrations of relaxin were similar and rose significantly in all groups at each time point (P < 0.05). On day 6 there was no significant difference in the increment between the groups, but by day 10, circulating levels in the P compared to the NP and those in the PH compared to the NPH group were significantly greater (P < 0.05). By day 22 the difference between
the PH and the P groups was significant (P < 0.05). Relaxin levels correlated with progesterone levels on day 10 in the NP and P groups (r = 0.633; P < 0.05 and r = 0.697; P < 0.05, respectively) and with estradiol levels in the P group only on days 6 and 22 (r = 0.659; P < 0.05 and r = 0.783; P < 0.05, respectively). These data demonstrate that in women undergoing in vitro fertilization, relaxin levels increase during the luteal phase, and in those women who establish a pregnancy, the values are significantly greater by day 10. The administration of hCG in the early luteal phase, before implantation, to women who subsequently become pregnant significantly increased the level of circulating relaxin on day 22. The positive correlation between relaxin levels and ovarian steroid levels in the groups not receiving exogenous hCG suggests that a common factor may control the release of both. (J Clin Endocrinol Metab 72: 1042-1047, 1991)
R
ELAXIN can first be detected in peripheral plasma 6 days after the midcycle surge of LH; 4 days later, the concentration is significantly higher if conception has occurred (1). During pregnancy, the level of serum relaxin, as measured by a homologous RIA, is highest by the 10th week, at about 900 pg/mL, it then falls to a plateau of about 500 pg/mL for the remainder of the pregnancy (2); in contrast to pigs and rats (3, 4), there is no evidence in man for a prepartum surge in relaxin levels (5). The similarity in the patterns of serum relaxin and hCG levels throughout pregnancy (2) suggests that a causal relationship may exist between the two. This possibility is supported by the observation that exogenous hCG stimulates the release of relaxin in women Received September 24, 1990. Address all correspondence and requests for reprints to: Dr. Mark R. Johnson, Neuroendocrinology Unit, Charing Cross and Westminster Medical School, Charing Cross Hospital, Fulham Palace Rd, London W6 8RF United Kingdom. * Supported by a Williams Fellowship from London University and recipient of a Joint Research Committee grant from the Trustees of the Westminster Hospital Group.
during the late luteal phase (6). We have undertaken a systematic study to determine the extent to which hCG and pregnancy may affect the release of relaxin and other ovarian hormones around the periimplantation period in infertile women who are being treated by in vitro fertilization (IVF) and embryo transfer (ET).
Subjects and Methods Subjects Forty-eight patients undergoing IVF who were under 38 yr of age and had tubal damage only as a cause of their infertility were entered in the study. All subjects received clomiphene citrate (Clomid, Merrel Dow Pharmaceuticals Ltd., Uxbridge, Middlesex, United Kingdom; 100 mg, orally) on days 2-6 of their menstrual cycle, human menopausal gonadotropin (Pergonal, Serono Laboratories, Welwyn Garden City, Herts, United Kingdom; two to six ampoules per day, im, depending on previous responses) was started on days 2-4 (depending on the length of the normal cycle) and continued until the leading follicle reached a mean diameter of 17 mm and at least three follicles greater than 14 mm were present. hCG (Profasi, Ser-
1042
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 23 November 2015. at 01:44 For personal use only. No other uses without permission. . All rights reserved.
EFFECT OF hCG AND PREGNANCY ON RELAXIN
1043
TABLE 1. The concentrations of plasma hormones [geometric mean and range (in parentheses)] before and after ET in women undergoing IVF (14 with and 12 without hCG luteal phase support) who did not become pregnant Day relative to ET -4
+
-
Luteal support: Relaxin (pg/mL)
30 (32-42) 16 (4-65) 4587 (2164-7879)
Progesterone (nmol/L) Estradiol (pmol/L)
10
6
+
47" (27-87) 103° (53-220) 19936 (890-6645)
28 (20-94) 16 (3-34) 4357 (2486-5599)
+
6
51 (22-103) 12 (3-45) 3976 (89-1295)
70° (23-212) 248° (120-550) 3206h (1580-9795)
71 6 (20-310) 17 (6-132) 675" (300-4485)
° P < 0 . 0 1 us. basal value. 6 P < 0.05 us. basal value. TABLE 2. The concentrations of plasma hormones before and after ET in women undergoing IVF (8 with and 12 without hCG luteal phase support) who became pregnant Day relative to ET -4
Progesterone (nmol/L) Estradiol (pmol/L)
22
10
-
+
-
+
-
+
-
+
28 (20-61) 16 (3-58) 5046 (2936-11316)
25 (20-50) 8.5 (3-23) 5267 (3449-7364)
54" (28-100) 95b (40-210) 2323* (1545-3470)
110° (30-624) 284° (158-690) 4726 (1700-12945)
4726 (180-1181) 1646 38-425) 20246 (475-3770)
791° (241-1923) 270° (138-645) 5679 (2230-14855)
2194° (1136-4682) 1806 (46-325) 4139 (1260-9795)
6052° (2705-12333) 290" (110-735) 8627 (3695-34735)
Luteal support: Relaxin (pg/mL)
6
° P < 0.05 vs. basal value. P < 0.01 vs. basal value.
b
ono, Welwyn Garden City, Herts, United Kingdom; 5000 IU, im) was administered, and oocytes were collected 34-38 h later. Two days later, two or three embryos were transferred to the uterus. Subjects were allocated randomly to receive hCG (2000 IU, im) or placebo on the day of ET (day 0) and on day 3. Blood samples were taken on days —4, 6, and 10, and on day 22 in subjects who became pregnant. Blood was taken into lithium-heparin tubes, and the plasma was separated by centrifugation and stored at —20 C before analysis. Pregnancy was defined as a positive immunochemical pregnancy test (hCG, >25 U/L) 14 days after ET and was confirmed by the presence of a gestational sac (as observed by transvaginal ultrasonography 7 days later). The protocol was approved by the Ethics Committee of King's College Hospital. Methods The concentration of relaxin was measured in unextracted plasma by a noncompetitive enzyme-labeled immunoassay (7). The standards, from 20-1250 pg/mL, were prepared in pooled normal male plasma. The working range of the assay (defined as the lowest and the highest value with a coefficient of variation of
