Serum copper in long-term users of copper intrauterine devices.

A study was undertaken to determine whether long-term use of a copper intrauterine device (IUD) was associated with any alteration in the serum copper levels and thereby whether absorption of copper from the device in utero could result in copper toxicity. Serial estimations in copper IUD wearers showed that there was no alteration in serum copper levels for a period of up to 24 months. The mean range and frequency distribution of serum copper levels in long-term copper IUD wearers was similar to that seen in the normal population. There was no difference in the mean 24-hour urinary copper excretion between the control group and the copper IUD wearers. Data suggest that the copper released from a copper IUD may not be readily absorbed from the uterine fluid. This hypothesis needs verification.