Louisa was born in 1826 to Christian Tetzner and Anna Sophie Mordhorst. Her birthplace was the town of Krusendorf in the German portion of the Dano-German duchy of Schleswig (now in Germany, just south of Denmark). In 1849, Louisa left her home in disgrace after having a child by her Danish boyfriend. She, with her baby son, followed him north into central Denmark where she met Hans Madsen. In 1851, Louisa and Hans married in the town of Erritsų, just south of the city of Fredericia.
For a continued overview of Hans, Louisa, and their children, see Family of Hans and Louisa Madsen.
Details of the life of Louisa Tetzner Madsen, Hans Madsen, and especially their son, P.W. Madsen, can be found in The Madsen Family History by W. Dee Halverson.