30th April 2024

A 45-year-old woman presents with fatigue, joint pain, and a history of irregular menstrual cycles.

A 45-year-old woman presents with fatigue, joint pain, and a history of irregular menstrual cycles. She reports her father had liver disease. Physical examination reveals mild skin pigmentation. She does not consume alcohol.

Investigations:

Serum transferrin saturation: 50%

Serum ferritin: 600 picomols/L (normal: <200 nanograms/mL for women)

Liver function tests: Elevated ALT and AST

Fasting blood sugar: Elevated

Which additional investigation is most likely to help with the diagnosis?