Vitamin A Status in Patients With Vocal Fold Leukoplakia

Inclusion Criteria:

1. Willing to provide informed consent.
2. Willing to comply with all study procedures and be available for the duration of the study.
3. Ability to take oral medication.
4. At least 18 years of age.
5. Leukoplakia study groups:

   1. Leukoplakia due to hyperkeratosis with dysplasia: biopsy-confirmed diagnosis of hyperkeratosis with dysplasia.
   2. Leukoplakia due to hyperkeratosis with no dysplasia: biopsy-confirmed diagnosis of hyperkeratosis with no dysplasia.
6. Control group: Laryngoscopy showing no evidence of vocal fold epithelial disease.

Exclusion Criteria:

1. History of malignant vocal fold epithelial pathology.
2. History of metabolic or liver disorder.
3. History of anorexia or bulimia.
4. Pregnant, lactating, or planning on becoming pregnant during the study period.
5. History of \>4.5 kg weight loss in the past 90 days.
6. Medical or other inability to complete an 8 hour fast.
7. Acute respiratory or gastrointestinal illness.
8. Currently incarcerated.
9. Impaired decision-making capacity.
10. No or limited English speaking ability; illiterate or low-literacy ability.
11. Profound visual or hearing impairment that limits written or verbal communication.
12. Status relationship with a member of the study team.
13. Not suitable for study participation due to other reasons at the discretion of the investigators.