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RecruitingNCT05733078Updated Jan 11, 2024

Effect of Vitamin C Supplementation in Patients With Primary Hypothyroidism

A Phase 2 interventional study of Vitamin C and Oral Rehydration Salt Formulations in Hypothyroidism, Primary Hypothyroidism and Vitamin C Deficiency, sponsored by Dr Adnan Agha. Recruiting at 1 site in United Arab Emirates. Open to participants aged 18 Years to 99 Years. Per ClinicalTrials.gov, last updated 2024-01-11.

Sponsored by Dr Adnan Agha · Phase 2, Interventional, and Treatment

From the registry’s dates

  • Primary completion was expected by Mar 2024, 2 years 8 months ago, but the record still lists the study as recruiting.
  • Started Nov 2023; still recruiting 3 years later.
Phase
Phase 2
Study type
Interventional
Enrollment
40
Allocation
Randomized
Ages
18 Years to 99 Years
Sex
All
01

Study summary

Thyroid disease affects almost a quarter of a billion individuals worldwide and more than 50% of them being not aware of this condition. The commonest thyroid disease is iodine deficiency related thyroid dysfunction with nearly 2 billion people around the globe at risk with insufficient iodine intake. Autoimmune thyroid disorders are commonest cause of thyroid dysfunction in iodine sufficient parts of the world. Sub-optimally or untreated hypothyroidism can lead to cognitive decline, dyslipidemia, hypertension, infertility as well as cardiovascular and neuromuscular problems. The prevalence of hypothyroidism can vary in general population with up-to 5.3% people with overt hypothyroidism based on studies from the West, with estimated 10% of the population having subclinical hypothyroidism globally. In the gulf region however, there are no national studies that provide insight into exact prevalence of hypothyroidism, however some cross-sectional screening studies indicate frequency of hypothyroidism to be as high as 5-10%.

Levothyroxine is a synthetic hormone with structure similar to naturally occurring thyroxine, and it is used as replacement monotherapy of hypothyroidism. It is mainly absorbed via small intestine. The optimal daily levothyroxine dosage requirement is 1.6 microgram/kg body weight/day, which can normalize TSH in most patients, however many studies indicate that nearly half the patient on replacement therapy may not attain a normal TSH and require further doses, possibly due to interference or malabsorption. Multiple dose change and repeated diagnostic procedures in these patients can not only increased health costs but increased of ensuing complications secondary to sub-optimally controlled hypothyroidism. Instead of increasing levothyroxine doses and getting variable response, recent study have shown improvement in thyroid function by adding on vitamin C alongside levothyroxine dose, albeit only in a specific subset of patient having gastritis. The effect of Vitamin C on improving levothyroxine also been shown to be effective over a short period in a non-randomized, non-controlled setting. Our study aims to investigate whether addition of vitamin C to levothyroxine can improve the biochemical and clinical thyroid status in a randomized controlled setting.

Read the detailed description

Nearly 20-50% patients with hypothyroidism do not achieve normal TSH on levothyroxine replacement and two common reasons are interference in absorption and compliance. This study aims to evaluate the effects of oral vitamin C given alongside oral levothyroxine in compliant patient with clinical/biochemical hypothyroidism despite being on optimal daily dose of levothyroxine, in terms of biochemical improvement of thyroid function status. This may help patients requiring more than recommended daily dose (> 1.6 ug/kg per day of oral levothyroxine) to achieve euthyroid status without increasing total levothyroxine dose by just adding vitamin C (which authors feel may help with improving absorption of Levothyroxine).

OBJECTIVE:

To measure the biochemical and clinical responses in thyroid status with additional oral vitamin C in patients with features of hypothyroidism who are already on recommended daily dose of >1.6 ug/kg/day of oral levothyroxine.

METHODOLOGY:

STUDY DESIGN:

This is a prospective randomized controlled study in which all adult patients known to have primary hypothyroidism, attending Tawam Hospital Endocrine clinic for the last 6 months, and fulfilling the criteria below, will be selected. We will aim to include minimum 32 patients. The study power calculations for population of Al Ain estimated 650,000 with an estimated global prevalence of hypothyroidism being around 6% and expected 20-50% (taken as 33%) with suboptimal thyroid function, indicates need for minimum 31 patient with confidence interval of 95% and margin of error as 5%. The patients will be randomized to either control or intervention group (16 in each group).

02

Conditions studied

  • Hypothyroidism
  • Primary Hypothyroidism
  • Vitamin C Deficiency

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03

In context

Hypothyroidism

217 studies on the registry are indexed under Hypothyroidism; 50 are open to participants now.

This study's planned enrollment of 40 is below the median of 70 across 109 interventional studies indexed under Hypothyroidism.

Browse Hypothyroidism studies →

Lead sponsor

Dr Adnan Agha is the lead sponsor of 4 studies on the registry; 2 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years to 99 Years
Sexes eligible
All
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

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

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
05

Study design

Phase
Phase 2
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Single (Participant)
Enrollment
40 participants (estimated)

Study arms

  • Placebo comparator
    Control / Crossover

    The patients in control group will have a oral rehydration effervescent tablet to take with their usual dose of Levothyroxine for 12 weeks, with thyroid function tests assessed at 6 and 12 weeks. Crossover: After first 12 weeks, the control group will then be provided vitamin C (intervention) effervescent tablets to use 1 gram daily with their usual dose of Levothyroxine for 12 weeks, with thyroid function tests assessed at 6 and 12 weeks to see if there is any difference on biochemical testing or clinical scores.

    Drug: Oral Rehydration Salt Formulations

  • Experimental
    Intervention

    The patient in test group will be provided vitamin C effervescent tablets to use 1 gram daily with their usual dose of Levothyroxine for 12 weeks, with thyroid function tests assessed at 6 and 12 weeks. The patients who wish to continue at the end of 12 weeks will be provided another 12 weeks supply of vitamin C effervescent tablets to use 1 gram daily with their usual dose of Levothyroxine for with thyroid function tests and clinical score assessed at the end of week 24.

    Drug: Vitamin C

Interventions

  • The patient in test group will be provided vitamin C effervescent tablets to use 1 gram daily with their usual dose of Levothyroxine for 12 weeks, with thyroid function tests assessed at 6 and 12 weeks. The patients who wish to continue at the end of 12 weeks will be provided another 12 weeks supply of vitamin C effervescent tablets to use 1 gram daily with their usual dose of Levothyroxine for with thyroid function tests and clinical score assessed at the end of week 24.

  • DrugOral Rehydration Salt Formulations

    The patients in control group will have a oral rehydration effervescent tablet to take with their usual dose of Levothyroxine for 12 weeks, with thyroid function tests assessed at 6 and 12 weeks. The control group will then be provided vitamin C (intervention) effervescent tablets to use 1 gram daily with their usual dose of Levothyroxine for 12 weeks, with thyroid function tests assessed at 6 and 12 weeks to see if there is any difference on biochemical testing or clinical scores.

    Also known as: Vitamin C

06

What researchers measure

Primary outcomes

  1. Change in Thyroid function (TSH)

    The primary outcome will be assessing the change in TSH levels in mIU/ml before and after supplementation the same levothyroxine dose with and without intervention (1 gram of effervescent vitamin C).

    Time frame: 24 weeks

  2. Change in Thyroid function (T4)

    The primary outcome will be assessing the change in T4 levels in pmol/L before and after supplementation the same levothyroxine dose with and without intervention (1 gram of effervescent vitamin C).

    Time frame: 24 weeks

  3. Change in Thyroid function (T3)

    The primary outcome will be assessing the change in T3 levels in pmol/L before and after supplementation the same levothyroxine dose with and without intervention (1 gram of effervescent vitamin C).

    Time frame: 24 weeks

Secondary outcomes

  1. Change in clinical status

    The clinical response will be assessed by evaluating for any change in Billewicz index scoring scale questionnaires before and after intervention. Billewicz index score ≥ +25 for overt hypothyroidism; score of -30 to +25 (above -30 and below +25) for subclinical hypothyroidism; and score ≤ -30 for excluding hypothyroidism)

    Time frame: 24 weeks

07

Study locations

1 of 1 sites recruiting
08

References and documents

Publications

  • de Benoist B, McLean E, Andersson M, Rogers L. Iodine deficiency in 2007: global progress since 2003. Food Nutr Bull. 2008 Sep;29(3):195-202. doi: 10.1177/156482650802900305. PubMed 18947032 ↗
  • Jubiz W, Ramirez M. Effect of vitamin C on the absorption of levothyroxine in patients with hypothyroidism and gastritis. J Clin Endocrinol Metab. 2014 Jun;99(6):E1031-4. doi: 10.1210/jc.2013-4360. Epub 2014 Mar 6. PubMed 24601693 ↗
  • Virili C, Antonelli A, Santaguida MG, Benvenga S, Centanni M. Gastrointestinal Malabsorption of Thyroxine. Endocr Rev. 2019 Feb 1;40(1):118-136. doi: 10.1210/er.2018-00168. PubMed 30476027 ↗

Individual participant data

Plan to share: No

09

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Jan 11, 2024, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT05733078
Lead sponsor
Dr Adnan Agha
Responsible party
Dr Adnan Agha (Assistant Professor, Internal Medicine, College of Medicine and Health Sciences, United Arab Emirates University, United Arab Emirates University) — Sponsor-investigator
First posted
Feb 17, 2023
Start date
Nov 1, 2023
Primary completion
Mar 2024 (estimated)
Completion
Jun 2024 (estimated)
Last update
Jan 11, 2024

Study contacts

Adnan Agha, FRCP
Contact
adnanagha@uaeu.ac.ae
+971562790723 ext. 7677
Adnan Agha
principal investigator · United Arab Emirates University

Oversight

Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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