Metabolism of HCG in Man

Abstract

The metabolic clearance rate (MCR) of human chorionic gonadotropin (HCG) was determined in normal male and female subjects following the intravenous and intramuscular administration of 10,000 IU of HCG. The mean MCR (I/day) in the iv experiments was 3.38 for men and 3.86 for women. These values are approximately 1/10 of the MCR value reported for human luteinizing hormone. Following the iv administration, the plasma disappearance curve showed an initial fast component with a half-life of 5.1 and 5.6 hr for males and females, respectively, while the half-life for the second, slow component was 23.6 for males and 23.9 hr for females. (J Clin Endocr 29: 92, 1969) H UMAN chorionic gonadotropin (HCG) has been widely used to induce ovulation in women pretreated with either human menopausal or pituitary gonadotropins. The dose and number of injections have been variable and their timing mainly empirical (1, 2). In very few studies has an attempt been made to determine the blood levels of HCG at various intervals following its administration (3,4,32).In the study to be reported here, HCG has been administered either intravenously or intramuscularly to a group of healthy men and women, and plasma concentration of HCG has been measured at frequent intervals up to 120 hours following the injection. The results confirmed previous studies indicating that HCG disappears only slowly from the blood (3), and have made it possible to calculate the rate constant of disappearance, and the metabolic clearance rates of HCG following both iv and im injection. The rate of disappearance of HCG was much slower than that of any other human protein hormone, including human luteinizing hormone (HLH). In some respects this characteristic is therapeutically desirable since it leads to

Regulation of Primate Testicular Luteinizing Hormone Receptors and Steroidogenesis

“…This pattern of response was typical ofthat seen in man (14) and is in marked contrast to the pattern seen in the laboratory rat, perhaps because of the prolonged halflife ofhCG in man when compared with the rat (15,16). Stimulation of the rat testis in vivo leads to a testosterone response within 15 min and a 5-to 10-fold increase by [2][3][4][5][6][7][8][9][10][11][12] h, followed by a decline to normal levels within 1-2 d depending upon the administered dose of gonadotropin (1,2).…”

Metabolic and renal clearance rates of purified human chorionic gonadotropin.

“…We gave purified hCG by continuous infusion, and our value for the MCR of hCG is 3.31+0.23 ml/min (or 1.88+0.08 ml/min per m2). In contrast, previous studies ofhCG metabolism employed analysis ofits disappearance after a single injection of crude preparations ofhCG (2,3,5), or after removal ofhCG-producing tissue, e.g., delivery of the placenta (1,4). For example, Wide et al (2) calculated an MCR based on bioassay measurement of hCG of 2.33 ml/min; when a radioimmunoassay was used to measure hCG, these authors found a substantially different value of the MCR, [6][7][8][9][10] h; however, the latest time point at which the hCG level was determined was 24 h in two subjects and 5 h in the third.…”

“…The metabolism of human chorionic gonadotropin (hCG)1 has been the subject of a number of reports during the past 40 yr (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). It has been established that the hCG molecule has a plasma metabolic clearance rate (MCR) that is quite slow relative to the MCR of the pituitary glycoprotein hormones (1)(2)(3)(4)(5), and that urinary excretion accounts for some, but not all, of the metabolic disposal of hCG (1,2,(5)(6)(7)(8)(9)(10).…”

“…It has been established that the hCG molecule has a plasma metabolic clearance rate (MCR) that is quite slow relative to the MCR of the pituitary glycoprotein hormones (1)(2)(3)(4)(5), and that urinary excretion accounts for some, but not all, of the metabolic disposal of hCG (1,2,(5)(6)(7)(8)(9)(10). Techniques for quantitation of hCG metabolism have varied, and each has its limitations.…”

“…Furthermore, the persistence ofhCG secretion by some residual trophoblastic tissue may complicate the kinetic analysis. Some investigators have injected crude commercial preparations of hCG and have analyzed the kinetics of disappearance of hCG biological or immunological activity from blood (2,3,5). However, crude preparations of hCG contain immunologically active, but biologically inactive hCG-related peptides (5).…”