Gonadotropin measurement

The introduction of two-site immunometric assays significantly improved the method for gonadotropin measure-... 

Serum is the preferred specimen for gonadotropin measurements hemolyzed, lipemic, or icteric specimens should not be used. Both hormones are stable for 8 days at room temperature and for 2 weeks at 4 °C for longer periods, the serum specimen should be stored frozen at or below -20 C. Because of episodic, circadian, and cyclic variations in the secretion of gonadotropins, a meaningful clinical evaluation of these hormones may require determinations in pooled blood specimens, multiple serial blood specimens, or timed urine specunens. Urine specimens should not contain preservatives storage at or below —20 °C is recommended. 

Braunstein GD, Karow WG, Gentry WC, Rasor J, Wade ME. Fust-trim ester chorionic gonadotropin measurements as an aid in the diagnosis of early pregnancy disorders. Am J Obstet Gynecol 1978 131 25-32. 

O Leary P, Nichols C, Feddema P, Lam T> Aitken M. Serum progesterone and human chorionic gonadotropin measurements in the evaluation of ectopic pregnancy. Aust NZ J Obstet Gynaecol 1996 36 319-23. 

Cornea, A. and Michael Conn, P. (2002) Measurement of changes in fluorescence resonance energy transfer between gonadotropin-releasing hormone receptors in response to agonists. Methods 27, 333. 

Aizawa et al. developed immunosensors of the first type for syphilis and blood typing [228-230] based on measurements of the transmembrane potential across an immunoresponsive membrane. The potentiometric immunosensor using an antibody against human chorionic gonadotropin (hCG)... 

Gonadotropins are used to treat infertility in women with potentially functional ovaries who have not responded to other treatments. The therapy is designed to simulate the normal menstrual cycle as far as is practical. A common protocol is daily injections of menotropins for 9 to 12 days, until estradiol levels are equal to that in a normal woman, followed by a single dose of hCG to induce ovulation. Two problems with this treatment are risks of ovarian hyperstimulation and of multiple births. Ovarian hyperstimulation is characterized by sudden ovarian enlargement associated with an increase in vascular permeability and rapid accumulation of fluid in peritoneal, pleural, and pericardial cavities. To prevent such occurrences, ovarian development is monitored during treatment by ultrasound techniques and by measurements of serum levels of estradiol. 

Human chorionic gonadotropin is well absorbed after intramuscular administration and has a biologic half-life of 8 hours, compared with 30 minutes for LH. The difference may lie in the high sialic acid content of hCG compared with that of LH. It is apparently modified in the body prior to urinary excretion, because the half-life measured by immunoassay far exceeds that measured by bioassay. 

Receptors in the testis for FSH and LH may be determined for specific investigations, but the information for risk assessment provided by this determination is limited. Incubation of the testis ex-vivo with human chorionic gonadotropin (hCG) is of considerable importance, and that biosynthesis of androgens may be assessed by measurement of the incubation media. 

Total inhibin, measured on day 8 of human menopausal gonadotropin (hMG) in down-regulated cycles, is significantly correlated with estradiol levels, and is correlated with pregnancy (M5). 

One rare phenomenon occurring in patients undergoing IVF is empty follicle syndrome, the failure to aspirate oocytes from follicles. This can be predicted by measuring beta human chorionic gonadotropin levels 36 h after hCG administration (i.e., at the time of oocyte retrieval) (N4). Women with empty follicle syndrome have significantly lower levels of beta-hCG (range 0-9 mU/mliter) than controls without the empty follicle syndrome (range 106-290 IU/liter) (N4). The fact that this syndrome occurs only very rarely, and that at the time the beta-hCG level is known, the laboratory also has concluded that no oocytes are present in the follicular fluid, makes this test not very practical for everyday use. 

K9. Kulin, H. E., Bell, P. M., Santen, R. J., and Ferber, A. J., Integration of pulsatile gonadotropin secretion by timed urinary measurements an accurate and sensitive 3-hour test. J. Clin. Endocrinol. Metab. 40, 783-789 (1975). 

Saketos, M., Sharma, N., Adel, T., Raghuwanshi, M., and Santoro, N., Time-resolved im-munofluorometric assay and specimen storage conditions for measuring urinary gonadotropins. Clin. Chem. 40, 749-753 (1994). 

Radioimmunoassay may be used to measure the urinary ratio of total (free plus conjugated) testosterone to LH. Testosterone is measured in nmol/ litre, and LH in International Units of HMG-IR2/ litre (Human Menopausal Gonadotropin 2nd International Reference Preparation). A ratio in excess of 200 is abnormal. (R. V. Brooks et at, J. Steroid Biochem., 1979, 77, 913-917.)... 

Fig. S. Inhibition of the binding or rabbit anti-HCG to human chorionic gonadotropin (HCG) beads by differing amounts of HCG as measured by inhibition of [ I]PA binding. (A) Effect of varying antibody concentration on assay sensitivity. Inhibition curves were obtained using 13 ig of HCG beads and anti-HCG diluted li ( — 14,2(X) cpm bound), jhi (O—O 80(X) cpm bound), orj W (A—A 4250 cpm bound). (B) Effect of varying bead concentration on assay sensitivity. Inhibition curves obtained using anti-HCG diluted jin and either 40 ng (O—O 23,500 cpm bound), 13 /xg ( — 14,200 cpm bound), or 4.3 fig (A—A 6000 cpm bound) of HCG beads. In each case, 38,000 cpm of [ I]PA were added. From Langone. ...

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