Verbatim · Ayatollah A. Sistani
The bleeding that women above the age of sixty (lunar years) experience is not ruled as Haydh, and as obligatory precaution it is considered as Istihadha, and there is no difference in ruling if she was a Sayyidah or not. As for the bleeding between the age of fifty and sixty years (lunar) years it is considered Haydh, if it has the attributes of her menstruation (monthly period), whether she was a Sayyidah or not. *Sixty lunar years is equivalent to approximately fifty eight solar years and eighty days. *A Sayyidah is a female descendant of Hashim, the great grandfather of Prophet Mohammed (Peace be upon him).
Ayatollah A. Sistani sistani.org Q&A #26338 other marjas may differ
A note on lunar years: 60 lunar years ≈ 58 solar years and 80 days. The Tuhr menopause calculator handles the conversion and shows the A. Makarem variant alongside (per ISSUE 194: 50 for non-Qurayshi women, 60 for Qurayshi); A. Khamenei does not issue a binding ruling on this question and refers muqallids to another mujtahid.