The effects of Norplant on clinical chemistry in Singaporean acceptors after 1 year of use: I. Haemostatic changes.

A longitudinal study of coagulation parameters was carried out on 100 Singaporean acceptors using the levonorgestrel subdermal implants NORPLANT for contraceptive purposes. At the end of 1 year of use, results from this on-going study indicate that these subjects may have an increased predisposition to thrombosis as evidenced by significant increase in platelet count and aggregability. The results also show that NORPLANT acceptors may have an enhanced potential for hypercoagulation - with a significant shortening of their Prothrombin Time and Activated Partial Thromboplastin Time and increases in Factors V and X. As previously documented, mean values for haemoglobin and haematocrit were significantly elevated by the end of 1 year. A number of other parameters achieved statistically significant differences by the end of 1 year but these were probably due to the large sample size involved and were therefore not likely to be of much clinical importance.