Gerdien is a medical doctor who obtained her MBChB degree from the University of the Free State in 2014. She completed her internship and community service in Kimberley (Robert Mangaliso Sobukwe Hospital and Diskobolos Military Sick Bay respectively) after which she worked in resource limited primary healthcare for two years.

In the beginning of 2020, she started working as a volunteer (and later a research assistant) in the Division of Clinical Haematology at Groote Schuur Hospital during the Covid-19 pandemic. Currently she is the National Training Coordinator of BLOODSA (part time) and spends some of her time as Medical Officer in the Combined Specialist HHT (Hereditary Hemorrhagic Telangiectase) clinic and sub-Investigator in Clinical Trials at Groote Schuur Hospital.