Ketogenic dietary therapies (KDTs) are well-established, safe, non-pharmacologic treatments used for children and adults with drug-resistant epilepsy and other neurological disorders. Ketone bodies levels undergo a significant inter-individual and intra-individual variability and can be affected by several factors. This evidence suggests the need for personalized monitoring for diet optimization, especially at the beginning of the treatment but during whole follow-up. Possible variations in glycemia and ketone bodies' blood level according to different phases of menstrual cycle have not been systematically assessed yet, but this time window deserves special attention because of hormonal and metabolic related changes. We present the methodological protocol for a longitudinal, multicentric study aimed at searching for subtle changes in ketone bodies blood level during menstrual cycle in epileptic female patients undergoing a stable ketogenic diet. The study will be divided into two phases. The first one will be purely observational, aiming at the assessment of ketonemia during menstrual cycle. Whether this finding will be confirmed, a second phase of ketogenic diet therapy adjustment will be scheduled.

Inclusion Criteria:

• Patients with drug resistant epilepsy or GLUT1DS undergoing KD from at least 3 months before inclusion to the study
• Patients who had menarche at least 3 months before inclusion to the study
• Absence of recognized endocrinologic problems/ disease

Exclusion Criteria:

• Patients who experienced secondary amenorrhea
• Patients who have irregular menstrual cycle
• Pregnant patients

• Patients who had menarche at least 3 months before inclusion to the study
• Patients undergoing KDTs from at least 3 months

Eligible participants will be female patients aged 13 years or older, with regular menstrual cycle, who have been undergoing a KDT for at least 3 months and thus previously diagnosed with Drug resistant epilepsy or GLUT1DS.