Madrenas has a degree in law from the Autonomous University of Barcelona (UAB) and, after completing her higher education, from 2003 to 2010 she was president of the Girona Property Agents' Association and vice-president of the Catalan Council of COAPI.

During Carles Puigdemont's term as mayor, she became his trusted auxiliary, appearing as his representative during neighbourhood disputes.

[5] In 2011, Puigdemont signed her up to be number three on the list for the Municipal Elections for Girona City Council [ca].

[5][6] In January 2016, after the sudden investiture of Carles Puigdemont as the new president of the Generalitat of Catalonia, Albert Ballesta [ca] became the new mayor of the city and Madrenas continued to head his posts in the city council but adding to them the competence of town planning.

Less than three months later, Albert Ballesta resigned[7][full citation needed] due to the problems he had in reaching agreements with the other parties to approve him as mayor.