Footnotes

• Contributors JOS conceptualised the letter, and SCG contributed with original ideas and reviewed the letter prior to submission.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

• Competing interests JOS consults a medical diagnostic laboratory in the laboratory diagnostics of inborn errors of ketone body metabolism.

• Provenance and peer review Not commissioned; internally peer reviewed.