CONTROL Surveillance

Hypothyroidism often results from autoimmune thyroid disease or thyroid resection1. In the majority of cases, hypothyroidism can be treated effectively by oral thyroid hormone supplementation, most commonly with levothyroxine. Key factors adversely affecting levothyroxine performance have been widely reported in the clinical literature. They include comorbid conditions and their treatments, diet, tolerability of medication and compliance with instructions for administration.

Some patients claim allergies to excipient ingredients found in levothyroxine tablet formulations such as food dyes, wheat starch, talc, etc1. Although their clinical significance is unknown, such allergies may adversely affect patient compliance and satisfaction with therapy.

The primary objective of the CONTROL Surveillance Project was to specifically quantify the prevalence of factors that are known to adversely affect levothyroxine performance including:

  • GI conditions known to affect drug absorption
  • Sensitivity to inactive ingredients contained in tablet drug formulations (i.e., excipients)
  • Patient use of Rx and OTC medications, vitamins, foods/beverages
  • Patient understanding and compliance with levothyroxine administration guidelines (e.g., timing before meals)
The protocol and appropriate related documents were reviewed and approved by IntegReview IRB, Austin, Texas. Participants were selected from a large proprietary database and identified as having primary hypothyroidism. They received email invitations and were provided a confidential link for consent to participate in the 21-question online survey.

Inclusion Criteria- each subject was required to meet all of the following criteria:

  • Being treated with prescription medication for hypothyroidism
  • At least 19 years of age
  • A U.S. resident
  • Voluntary agreement to provide informed consent
  • Able to read English
  • Willing and able to complete the survey

Exclusion Criteria – any subject who met the following criterion was excluded:

  • Not taking prescription medications to treat hypothyroidism

Almost half (435/925 or 47.03%) of all respondents reported that they have GI conditions that may affect levothyroxine absorption2

Hypothyroid Patients on levothyroxine receiving medication for relevant concomitant diseases/conditions2,3

Acid reflux or GERD 313 33.8%
 Irritable Bowel Syndrome 90 9.7%
 Lactose intolerance 72 7.8%
 Gastric bypass or bowel resection 28 3.0%
 H. pylori infection 19 2.1%
 Gastroparesis 15 .6%
 Celiac disease 10 1.1%
 Ulcerative colitis 10 1.1%
 Crohn’s disease 6 0.6%
 Atrophic gastritis 1 0.0%
 Other* 157 17.0%
 None of the above 488 52.8%

* Other = numerous GI and non-GI conditions.
Note: because patients could specify more than one concomitant disease or condition, total of last column exceeds 100%.

More than 31% of Patients Have Experienced a Levothyroxine Dose Change within the Past 12 Months with 8% Receiving 2 or More Dose Changes


Patients Self-reporting GI Conditions are More Likely to Experience 2 or More Dose Changes in the Past 12 months

15.2% (141/925) of Patients Surveyed Reported Sensitivities to Foods/Ingredients that Can Affect levothyroxine


*Self- reported allergies to foods or ingredients including food dyes, wheat starch, lactose and sucrose. For a complete list of excipients used in each levothyroxine tablet formulation, please refer to the Full Prescribing Information for each product.
  • Many patients experience frequent levothyroxine dose changes (≥ 2/year). In CONTROL Surveillance, frequent dose changes were associated with the presence of GI comorbidities and the use of drugs to treat them
  • Allergies to foods and food ingredients (food dyes, wheat starch, lactose and sucrose in particular) may be more common than has been generally perceived
  • Reprint – The CONTROL Surveillance Project was published in Drugs R&D January 2015. Click here to view the pdf.
  • Summary – This slide presentation highlight the key findings presented in the CONTROL Surveillance Project pdf

Practice support material to help identify patients who may be at risk for Levothyrosine malabsorption or tolerability issues

For medical inquiries about the CONTROL Surveillance Project, call 1-888-383-1733 or email your request to

Azeez Farooki, MD
Dept. Endocrinology
Memorial Sloan Kettering Cancer Center, New York, NY

To learn more about a levothyroxine free of dyes, gluten(wheat starch), alcohol, lactose, and sugar, click here.


1Khandelwal D, Tandon N. Overt and subclinical hypothyroidism: who to treat and how. Drugs. 2012;72:17-33.
2McMillan M, Vora K, Thevathasan L. Factors Affecting Levothyroxine Therapy and Dosing. Results of the CONTROL Surveillance Project. 2015. 15th International Thyroid Congress. Orlando, FL. Poster No. 169.
3Data on file. Akrimax