Serum nickel concentration in normal menstrual cycle and after combined contraceptive pill.

Serum nickel concentration in the different phases of the menstrual cycle and after use of a combined contraceptive pill (Anovlar) was determined by atomic absorption spectrophotometry. Twenty ovulating females had their serum nickel level measured on day 5 and on day 27 of their cycle. Forty females using Anovlar for 6 months and 40 females using it for more than 3 years had their serum nickel determined. The serum nickel concentration of the non-pill users was higher on day 5 (2.52 +/- 0.46 micrograms/L) than on day 27 (2.21 +/- 0.37 micrograms/L p less than 0.05). In long-term users, the serum nickel (0.98 +/- 0.38 microgram/L) was less than the short-term users (2.38 +/- 0.35 micrograms/L, p less than 0.01) and the non-users (p less than 0.01). There was a negative correlation between the duration of pill use and the serum nickel level (r = -0.44, p less than 0.01). The significance of the decreased serum nickel level with long-term pill use remains to be determined.