Vitamin C supplementation for patients with primary hypothyroidism

Effect of Vitamin C Supplementation in Patients With Primary Hypothyroidism Requiring High Levothyroxine Dosage; a Randomized Control Trial

Phase 2 Interventional United Arab Emirates University · NCT05733078

This study is testing if taking vitamin C can help people with primary hypothyroidism better absorb their thyroid medication and improve their hormone levels.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment40 (estimated)
Ages18 Years to 99 Years
SexAll
SponsorUnited Arab Emirates University Academic / other
Locations1 site (Al Ain, Abu Dhabi)
Trial IDNCT05733078 on ClinicalTrials.gov

What this trial studies

This clinical trial investigates the effects of oral vitamin C supplementation in patients diagnosed with primary hypothyroidism who are already receiving an optimal dose of levothyroxine but still exhibit suboptimal thyroid function. The study aims to determine if vitamin C can enhance the absorption of levothyroxine, potentially allowing patients to achieve normal thyroid hormone levels without increasing their medication dosage. A total of at least 32 adult participants will be recruited from the Tawam Hospital Endocrine clinic, and their biochemical responses will be measured over the course of the trial. The study is designed as a prospective randomized controlled trial to ensure robust results.

Who should consider this trial

Good fit: Ideal candidates are adults over 18 years old with diagnosed primary hypothyroidism who have been on levothyroxine for more than 8 weeks but still have elevated TSH levels.

Not a fit: Patients with coeliac disease, malabsorption syndromes, or those with overt biochemical hypothyroidism may not benefit from this study.

Why it matters

Potential benefit: If successful, this approach could help patients achieve better thyroid function without the need for higher doses of levothyroxine.

How similar studies have performed: While the use of vitamin C in this context is novel, other studies have explored vitamin supplementation in thyroid disorders, but results have been mixed.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Age \> 18; both male or female
* Diagnosed to have Primary hypothyroidism \> 6 months.
* Under follow up in Endocrine clinic in Tawam hospital during the 6 months
* No evidence of secondary hypothyroidism (no pituitary problems/surgery or thyroid surgery/ablation)
* TSH \> 4 despite being on \> 1.6 ug/kg/day of Levothyroxine for more than 8 weeks

Exclusion Criteria:

* Presence of coeliac disease
* Presence of selenium or iodine deficiency
* Gastric/intestinal resection surgery or confirmed malabsorption syndromes
* Known mental health issues affecting compliance
* Patient unable to consent.
* Overt biochemical hypothyroidism with TSH \> 20 or T4 \< 6

Where this trial is running

Al Ain, Abu Dhabi

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions HypothyroidismPrimary HypothyroidismVitamin C Deficiency
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.