High-dose vitamin D with methimazole for children with Graves' disease

Impact of Vitamin D Therapy on Thyroid Function and Antibody Levels in Pediatric Graves' Disease: A Pilot Feasibility Trial

Phase 2 Interventional Northwell Health · NCT07369063

This pilot tests whether adding high-dose vitamin D to standard methimazole helps children 9–17 with newly diagnosed Graves' disease improve their thyroid hormone and antibody levels.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment30 (estimated)
Ages9 Years to 17 Years
SexAll
SponsorNorthwell Health Academic / other
Locations1 site (New Hyde Park, New York)
Trial IDNCT07369063 on ClinicalTrials.gov

What this trial studies

This randomized, single-site pilot feasibility trial will enroll children aged 9–17 newly diagnosed with Graves' disease and randomize them 1:1 to methimazole plus high-dose ergocalciferol versus methimazole alone (with up to 1,000 IU/day vitamin D allowed in the control arm). The primary focus is feasibility—measuring recruitment and adherence rates, completeness of data collection, and barriers to scaling a larger trial—while also collecting exploratory laboratory outcomes. Investigators will track thyroid antibodies (TRAb, TSI) and thyroid hormone panels (Total T3, Free T4, Total T4, TSH) over the study period to explore biological signals. The trial is conducted at Pediatric Endocrinology, Northwell Health in New Hyde Park, NY.

Who should consider this trial

Good fit: Children aged 9–17 years with a new biochemical and antibody-confirmed diagnosis of Graves' disease who are starting methimazole and meet calcium and vitamin D criteria are ideal candidates.

Not a fit: Patients with very high baseline vitamin D (>80 ng/mL), abnormal calcium, conditions affecting vitamin D metabolism, or on medications that alter vitamin D or thyroid function are unlikely to benefit from the intervention.

Why it matters

Potential benefit: If successful, adding high-dose vitamin D could help lower thyroid antibody levels or normalize thyroid hormones faster, potentially improving disease control or reducing treatment duration.

How similar studies have performed: Observational studies have linked low vitamin D to Graves' disease risk, but randomized interventional data—especially in pediatric patients—are limited, so this approach is relatively novel in children.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* All new pediatric participants aged 9-17 years with a new diagnosis of GD who will be started on methimazole, will be offered to participate at the time of diagnosis.
* Biochemical features include:
* Suppressed TSH \<0.1.
* Elevated T3
* Elevated Free T4
* Elevated T4
* Positive TSI or TRAb. The presence of antibodies is diagnostic.
* Our study will offer enrollment to non-English speaking participants

Exclusion Criteria:

* Initial hydroxy vitamin D levels \>80 ng/mL
* Hypocalcemia, corrected calcium based on albumin \<8.4 mg/dL
* Hypercalcemia, corrected calcium based on albumin \>10.5 mg/dL
* Conditions that affect vitamin D metabolism such as: malabsorption, chronic kidney or liver disease, nephrocalcinosis, hyperparathyroidism
* Current use of medications which are known to affect thyroid function or vitamin D metabolism such as thyroid hormone replacement, corticosteroids, anticonvulsants
* Allergy to vitamin D or methimazole
* Diagnosis of Hashitoxicosis or thyrotoxicosis (both TSH receptor antibody (TRAb) and thyroid-stimulating immunoglobulin (TSI) levels are negative)
* Participants under the age of 9 years at the time of diagnosis
* Pregnant participants
* Active or uncontrolled infections, other significant medical conditions deemed by the investigator to interfere with study participation or pose undue risk to the participant.

Where this trial is running

New Hyde Park, New York

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 Graves DiseaseGraves' DiseaseHyperthyroidismvitamin dgraves diseasehyperthyroidism
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.