Individually she finished sixth at the 2003 European Youth Olympic Festival.

[1] At the Norwegian championships she won gold in 2005–2009 and 2014–2015, and also took four silver medals and one bronze.

[1] She helped breaking the Norwegian record with 44.35 seconds at the 2008 edition, together with Siri Eritsland, Folake Akinyemi and Ezinne Okparaebo.

Slettum helped improve it to 44.29 seconds at the 2014 European Championships with Isabelle Pedersen, Christine Bjelland Jensen and Ezinne Okparaebo; then to 43.94 seconds at the 2015 European Team Championships Super League with Isabelle Pedersen, Ida Bakke Hansen and Ezinne Okparaebo.

Her hurdling result was 0.01 seconds shy of qualification mark for the 2018 European Championships.