Evaluation of Metformin Effect on the Fertility of Women Treated With 131I for Thyroid Cancer

Inclusion Criteria: 1. Female subjects in reproductive age \>18 \<45 years. 2. Subjects with diagnosed papillary thyroid carcinoma with various pathological stage TNM (I-II). 3. Subjects not treated with 131I 4. Willingness to comply with protocol procedures. Exclusion Criteria: 1. Hypersensitivity to metformin. 2. Subjects with polycystic ovarian syndrome or other diseases of the ovaries (primary / secondary ovarian failure). 3. Subjects taking metformin during last week. 4. Subjects with liver malfunction and abnormal hepatitis marker results (ALT and AST activity \>3ULN.\* 5. Subjects with eGFR below 45ml/min/1.73m2.\* 6. Subjects with lactic acidosis or having history of metabolic acidosis. 7. Subjects with serum AMH concentration\* below lower range norm. 8. Subjects with history of congestive heart disease NYHA stage III/IV. 9. Subjects with acute myocardial ischemia (CCS 3-4). 10. Subjects with history of sepsis or severe infection. 11. Subject with lung disease (uncontrolled asthma based on GINA 2000 Guidelines and COPD GOLD ≥ 3 stage). 12. Positive result of pregnancy test or pregnancy planned during the study. 13. Alcohol or other substance dependent syndromes. 14. BMI \<18.5 kg/m2. 15. Accompanying diseases with poor prognosis in the opinion of the researcher. 16. As per Investigator (or his designee) judgement, subject cannot participate in the study due to reasons (i.e. medical, psychiatric and/or social reason). 17. Unreliability or lack of cooperation. \*based on the laboratory results from screening visit