The effect of endogenous oestradiol levels on protein S concentration during a menstrual cycle and after GnRH analogues and gonadotropin therapy

Normal ranges and genetic variants of antithrombin, protein C and protein S in the general Chinese population. Results of the Chinese Hemostasis Investigation on Natural Anticoagulants Study I Group

BACKGROUND

Inherited deficiency of antithrombin, protein C and protein S, three important, naturally occurring coagulation inhibitors, might play a major role in the occurrence of venous thromboembolism in Chinese. The establishment of age- and gender-related normal ranges of these inhibitors is crucial for an accurate diagnosis of these deficiencies.

DESIGN AND METHODS

We designed a prospective cross-sectional study recruiting healthy adults from four university-affiliated hospitals in China. Antithrombin, protein C and protein S were studied by measuring their activity. Gene analysis was performed when natural anticoagulant deficiency was suspected. Polymorphisms of the factor V gene were searched for among subjects who were positive for activated protein C resistance.

RESULTS

In 3493 healthy Chinese adults (1734 men, 1759 women; age 17-83 years), we found higher age-adjusted activities for protein C and protein S in men than in women but no sex difference for antithrombin. In women, mean protein C and protein S activities increased with age. In men, mean protein C levels increased with age up to the age of 49 but decreased after 50 years old; mean protein S levels decreased after 50 years of age. Antithrombin levels remained stable over time in women but decreased significantly after 50 years of age in men. Reference values according to age and sex allowed the identification of 15 genetic variants (protein C:10, antithrombin:3, protein S:2) in subjects with protein activity below the 1(st) percentile.

CONCLUSIONS

This is the largest survey ever conducted in the healthy general Chinese population. These normal ranges provide the essential basis for the diagnosis and treatment of thrombosis in Chinese.

Frequency of protein S deficiency in general Japanese population

We measured protein S (PS) activity in a large group of Japanese subjects to study the frequency of PS deficiency. The study group comprised 213 men, ages 18-58 years, and 179 women, ages 18-60 years. PS activity in the total 392 subjects was 58-135% (mean +/- 2 SD), 65-135% in the men and 54-120% in the women. The men showed significantly higher levels of PS activity than the women (p<0.001). We identified 8 subjects (4 men and 4 women) in whom PS activity was lower than the mean-2SD for men and women, respectively. Moreover, we examined the classifications of PS deficiency. The frequency of PS deficiency in this study was 2.04% (Type I: 0.51%, Type II: 1.02%, Type III: 0.51%). Based on our findings, it would appear that the frequency of Type II PS deficiency in the Japanese population is approximately 1%. The screening of PS decrease should be judged by activity.

The role of matching menstrual data with hormonal measurements in evaluating effectiveness of postcoital contraception

The effectiveness of postcoital contraception can only be estimated. The most commonly used method of calculation compares the expected pregnancy rate in the exposed population to the resultant pregnancies after treatment. Estimation of the fertile period and the day of ovulation are critical to calculate the expected pregnancies. The aim of this study was to improve the accuracy of calculations by evaluating the hormonal status on the day of contraceptive treatment. A total of 483 consecutive women requesting postcoital contraception was included in a prospective observational trial. A blood sample was obtained at the moment of consultation to measure serum luteinizing hormone, estradiol, and progesterone concentrations. An ethinylestradiol-levonorgestrel combination (100 micrograms/500 mg for two doses, 12 h apart) was then prescribed. The fertile period was estimated according to previous hormonal studies in the normal cycling population. Of 483 women, 64 (13.25%) women were excluded because they presented irregular menstrual cycles and 37 (7.6%) women were lost to follow-up. Two pregnancies occurred in the remaining 382 women. Following Wilcox's and Trussell's methods, 21.1 and 17.75 pregnancies should be expected, yielding an overall treatment effectiveness of 90.52% (95% confidence interval [CI] 62.58%-97.6%) and 88.73% (95% CI 55.93%-97.12%), respectively. Hormonal data were available in 356 women; 303 of whom presented with regular cycles. Hormonal information in this group restricted the number of exposed cases to 88 women. Of the women included in Trussell's method of analysis, only 51 (51.5%; p < 0.05) were at risk using hormonal data. Fifty-six percent (95% CI 34.9%-75.6%) of women with luteinizing hormone levels > 20 IU/L were not between days-1 and +1 of the cycle. Hormonal studies suggest that methods based on pregnancy risk calculated by cycle day do not faithfully reflect the real exposure.