The Effect of Dietary Supplements for Pregnant Women on Levothyroxine Absorption

NCT04988802 | Unknown

• 1 other identifier: ZG2712TL
• Study Type: interventional
• Target: 37
• Locations: 1 country
• Sites: 1

Brief Summary

Hypothyroidism is a common disease that is successfully treated with the replacement of thyroid hormones in the form of levothyroxine. Levothyroxine is drug used in the first line of substitution therapy because it appropriately mimics physiological secretion of thyroxine (T4) and its peripheral conversion to triiodothyronine (T3). However, due to its narrow therapeutic index, and because it is administered at very low doses (micrograms - μg), it is particularly sensitive to the absorption phase interactions, which are due to its narrow therapeutic index, mainly clinically significant. In pregnancy, one of the goals is to maintain the values of thyroid stimulating hormone (TSH) in the lower part of the reference interval (below 2,5 milli-International units - mIU/L) for a proper child development. Also, due to increased nutritional needs during pregnancy, nutritional supplements are commonly used by pregnant women on their own initiative, but also often recommended by healthcare personnel. Reviewing the literature, we did not find high quality evidence to suggest the existence or to refute the interaction between dietary supplements for pregnant women and the absorption of levothyroxine. The aim of this study is to investigate this potential interaction between dietary supplements used in pregnancy and levothyroxine absorption in order to test the safety of the use of these preparations in pregnant women who are on replacement therapy with levothyroxine.

Conditions

Hypothyroidism Primary

Keywords

nutritional supplements; levothyroxine; pregnancy; safety

Outcome Measures

Primary Outcomes (1)

• Change in thyrothropin

  Change in thyrothropin larger than 1mIU/L

  8 weeks

Study Arms (2)

Patients taking food supplement with levothyroxine

ACTIVE COMPARATOR

Patients will start taking food supplement with levothyroxine in the evening, and the other tablet of the food supplement in the evening for 8 weeks.

Dietary Supplement: Prenatal Nutrients Solgar

Patients taking placebo with levothyroxine

PLACEBO COMPARATOR

Patients will start taking placebo with levothyroxine in the evening, and the other tablet of the placebo in the evening for 8 weeks.

Other: Placebo

Interventions

Prenatal Nutrients Solgar DIETARY_SUPPLEMENT

Patients will take dietary supplement Prenatal Nutrients from Solgar

Patients taking food supplement with levothyroxine

Placebo OTHER

Placebo capsules based on starch.

Patients taking placebo with levothyroxine

Eligibility Criteria

• Age: 18 Years+
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• female patients older than 18 on stable levothyroxine therapy for at least 6 months

You may not qualify if:

• Pregnancy
• thyroid carcinoma
• high cardiovascular risk
• coeliac disease
• Giardia Lamblia infection
• atrophic gastritis
• Helicobacter pylori infection
• previous bariatric surgery

Sponsors & Collaborators

• University Hospital Dubrava: lead

Study Sites (1)

Dubrava University Hospital

Zagreb, City of Zagreb, 10000, Croatia

RECRUITING

Related Publications (7)

• Fish LH, Schwartz HL, Cavanaugh J, Steffes MW, Bantle JP, Oppenheimer JH. Replacement dose, metabolism, and bioavailability of levothyroxine in the treatment of hypothyroidism. Role of triiodothyronine in pituitary feedback in humans. N Engl J Med. 1987 Mar 26;316(13):764-70. doi: 10.1056/NEJM198703263161302.

  PMID: 3821822 BACKGROUND

• Mandel SJ, Brent GA, Larsen PR. Levothyroxine therapy in patients with thyroid disease. Ann Intern Med. 1993 Sep 15;119(6):492-502. doi: 10.7326/0003-4819-119-6-199309150-00009.

  PMID: 8357116 BACKGROUND

• Toft AD. Thyroxine therapy. N Engl J Med. 1994 Jul 21;331(3):174-80. doi: 10.1056/NEJM199407213310307.

  PMID: 8008032 BACKGROUND

• Wiersinga WM. Thyroid hormone replacement therapy. Horm Res. 2001;56 Suppl 1:74-81. doi: 10.1159/000048140.

  PMID: 11786691 BACKGROUND

• Kabadi UM, Jackson T. Serum thyrotropin in primary hypothyroidism. A possible predictor of optimal daily levothyroxine dose in primary hypothyroidism. Arch Intern Med. 1995 May 22;155(10):1046-8.

  PMID: 7748047 BACKGROUND

• Helfand M, Crapo LM. Monitoring therapy in patients taking levothyroxine. Ann Intern Med. 1990 Sep 15;113(6):450-4. doi: 10.7326/0003-4819-113-6-450.

  PMID: 2143640 BACKGROUND

• Vrhovac i sur. Interna medicina. 3. izdanje. Medicinska biblioteka; 2003. str.1242-1244.

  BACKGROUND

MeSH Terms

Conditions

Hypothyroidism

Condition Hierarchy (Ancestors)

Thyroid Diseases; Endocrine System Diseases

Central Study Contacts

Tomo Lucijanic, MD

CONTACT

+385989375846; tomolucijanic@gmail.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: SUPPORTIVE CARE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: July 25, 2021
• First Posted: August 4, 2021
• Study Start: October 20, 2021
• Primary Completion: July 30, 2022
• Study Completion: September 30, 2022
• Last Updated: October 20, 2021

Record last verified: 2021-10

Data Sharing

• IPD Sharing: Will not share

Locations

CR (1)