You may be too old to have the mirena for contraception but it is ok as the progesterone part of HRT.
Please see below the info, which is taken from the Treatment option section at the top of the page
"Mirena is a levonorgestrel (type of progestogen) releasing system which sits inside the womb, gradually releasing the progestogen into the womb. It is licensed in the UK and Ireland as a contraceptive agent, for treatment of heavy periods and, from August 2004, also for the progestogen component of HRT. It can be used in both the perimenopause and postmenopause and it is particularly useful for:
Persistent progestogenic side effects from systemic HRT despite changes in type and route of progestogen.
When contraception is required along with HRT in the perimenopause.
When withdrawal bleeds on sequential HRT are heavy, after investigation if indicated. (see WHEN TO BE REFERRED )
With Mirena in place, systemic estrogen alone can be taken as the Mirena provides adequate protection of the womb lining and the estrogen dose and route can be tailored to meet the individual's needs.
Progestogenic absorption throughout the body is minimal so reducing progestogenic side effects. The effect of Mirena on the womb lining can significantly reduce bleeding and when used as part of an HRT regimen, in time, 30 to 60% of women have no bleeding at all. Although Mirena used for contraception is licensed for 5 years, the license for use for the progestogen part of HRT is currently 4 years."