Serum copper in long-term users of copper intrauterine devices

Effect of a novel copper chloride gel on endometrial growth and function in healthy volunteers

RESEARCH QUESTION

Does the application of a micro-dose of copper chloride gel increase endometrial production of vascular endothelial growth factor (VEGF) without compromising endometrial function or producing embryo toxicity?

DESIGN

An estimate of optimal dose was made based on cell culture studies. Ten healthy participants received an initial uterine application of placebo gel, followed by copper chloride gel (37.5 μM, 75 μM, or 150 μM dose) in a later hormone replacement cycle. Endometrial biopsies (day 5.5 luteal) and pelvic ultrasound were carried out during each cycle to evaluate endometrial function and growth. Uterine fluid was assessed for residual copper levels on the day of biopsy, and copper chloride gel underwent mouse embryos assay assessment for potential embryo toxicity.

RESULTS

The copper gel significantly increased endometrial VEGF expression (quantitative polymerase chain reaction), and also increasing endometrial thickness by an average of 2.2 mm compared with matched control cycles. The copper gel did not adversely affect endometrial morphology or maturation (histological dating and molecular receptivity testing), and mouse embryos assay studies showed no evidence of embryo toxicity. Furthermore, uterine cavity flush samples mostly lacked copper, with only negligible amounts present in one sample.

CONCLUSION

Applying copper chloride gel to the uterine cavity upregulated endometrial VEGF and significantly increased endometrial thickness and volume. No adverse effects on the endometrium or embryos were observed. Copper chloride gels show promise for treating suboptimal endometrial thickness if the results of this study are confirmed by larger randomized controlled trials.

Re-evaluation of the existing health-based guidance values for copper and exposure assessment from all sources

Copper is an essential micronutrient and also a regulated product used in organic and in conventional farming pest management. Both deficiency and excessive exposure to copper can have adverse health effects. In this Scientific Opinion, the EFSA 2021 harmonised approach for establishing health-based guidance values (HBGVs) for substances that are regulated products and also nutrients was used to resolve the divergent existing HBGVs for copper. The tightly regulated homeostasis prevents toxicity manifestation in the short term, but the development of chronic copper toxicity is dependent on copper homeostasis and its tissue retention. Evidence from Wilson disease suggests that hepatic retention is indicative of potential future and possibly sudden onset of copper toxicity under conditions of continuous intake. Hence, emphasis was placed on copper retention as an early marker of potential adverse effects. The relationships between (a) chronic copper exposure and its retention in the body, particularly the liver, and (b) hepatic copper concentrations and evidence of toxicity were examined. The Scientific Committee (SC) concludes that no retention of copper is expected to occur with intake of 5 mg/day and established an Acceptable Daily Intake (ADI) of 0.07 mg/kg bw. A refined dietary exposure assessment was performed, assessing contribution from dietary and non-dietary sources. Background copper levels are a significant source of copper. The contribution of copper from its use as plant protection product (PPP), food and feed additives or fertilisers is negligible. The use of copper in fertilisers or PPPs contributes to copper accumulation in soil. Infant formula and follow-on formula are important contributors to dietary exposure of copper in infants and toddlers. Contribution from non-oral sources is negligible. Dietary exposure to total copper does not exceed the HBGV in adolescents, adults, elderly and the very elderly. Neither hepatic copper retention nor adverse effects are expected to occur from the estimated copper exposure in children due to higher nutrient requirements related to growth.

A Literature Review of the Effects of Copper Intrauterine Devices on Blood Copper Levels in Humans

Copper is a trace mineral that is essential to human health but can be harmful in excess. Since the introduction of copper-containing intrauterine devices in the 1970s, their possible relationship to abnormal/toxic blood copper levels has been researched. Here, we summarize and interpret 12 studies that evaluate blood copper levels in users of copper-containing intrauterine devices. The data are inconclusive, with the results of eight studies indicating no increase in blood copper levels with use and the results of four studies showing significant increases in blood copper levels with use. Investigators in all studies reviewed appear to have evaluated for total copper rather than free copper (the form of copper that is toxic), which raises questions about the clinical significance of all research on this subject to date.

Long-term indwelling copper intrauterine device (IUD) found during primary infertility work up

Infertility is a public health concern worldwide. Hysterosalpingogram is a useful diagnostic tool to both evaluate the contours of the uterine cavity and to assess tubal patency. Intrauterine devices (IUDs) are the world's most prevalent form of long-acting reversible contraception. In this case, a 30-year-old P0 female, an immigrant from Jamaica, was referred for hysterosalpingogram for primary infertility workup. Under fluoroscopic imaging, an unexpected T-shaped IUD was visualized in the expected location of the uterus. The IUD lacked portions of the radiopaque copper lining. The patient initially denied IUD insertion. However, after further investigation, the patient's mother admitted IUD insertion at the age of 14 in Jamaica. This case raises a concern for the possibility of unexpected IUD discovery during infertility work up and emphasizes the importance of clinician awareness of the changes that may be seen on imaging when these devices are in place long-term.

Blood copper levels in Mexican users of the T380A IUD

OBJECTIVE

Copper T380A is one of the most commonly prescribed intrauterine devices (IUDs). However, there are few reports of its systemic health effects. This study evaluates the association between the use of T380A IUD and blood Cu levels in a group of Mexican users.

METHODS

Eighty-six T380A users and eight nonusers were recruited. Blood Cu levels were measured using an atomic absorption spectrophotometic technique.

RESULTS

In IUD users, mean blood Cu level was significantly higher than in nonusers, 216.63 vs. 107.47 microg/dL (p<or=.001), and above the normal blood Cu level range of 80-160 microg/dL. No significant difference in blood Cu levels was observed by age or length of time of IUD use.

CONCLUSIONS

The observed higher blood Cu levels among T380A user stands out in sharp contrast to previous reports of other types of Cu IUDs. Further research should evaluate if the observed levels are associated to toxic effects with the general population or special groups.

Serum and endometrial copper, zinc, iron and cobalt with inert and copper-containing IUCDs

Serum and endometrial copper (Cu), zinc (Zn), iron (Fe) and serum cobalt (Co) were measured in the mid-follicular and mid-luteal phases of the menstrual cycles in 30 Lippes loops users, 30 CuT-200 IUCD users and 24 matched controls by atomic absorption spectrophotometry. In the control group, there was no statistically significant difference in mean mid-luteal, compared to mid-follicular, levels of serum Cu, Zn, Fe and Co and endometrial Zn. Mid-luteal endometrium contained significantly higher mean Cu, and lower mean Fe levels. In Lippes loop users, compared to controls, the only statistically significant differences were lower mean mid-follicular serum Zn, lower mean endometrial Zn and Fe, and higher mean mid-luteal endometrial Fe. In CuT-200 users, compared to controls, there was significantly higher mean mid-follicular serum Zn and lower mean mid-luteal serum Co, higher mean mid-follicular endometrial Cu and lower mean mid-follicular endometrial Fe levels. Compared to Lippes loop, CuT-200 users had significantly higher mean mid-follicular serum Co and endometrial Cu and Zn, and lower mean mid-follicular endometrial Fe.