Her age is irrelevant. Her decade long history of blood clots, one of which could have killed her in 1998 and another in 2009.
She passed out and had a concussion in 2012, and in 2014 Bill Clinton said it took six months to recover. She started wearing Fresnell lenses for double vision, likely brain damage in 2013. She passed out and had balance problems from 2012 on.
Her severe coughing fits were evident in the Benghazi hearings in 2015 and have become very obvious today. Whether this is due to Parkinson's disease or another neurological problem that makes it hard to swallow, I don't know.
But years of health problems bad enough to say she's disqualified for health reasons no matter her age.