Fasting Requirement for Levothyroxine Presents Challenges

TOPLINE:

Nearly all patients reported receiving instructions to take levothyroxine (LT4) while fasting, but a third did not adhere to this.

Approximately half of patients reported being burdened with postponing breakfast and two thirds expressed a preference for non-fasted LT4 ingestion. About a quarter skipped breakfast because of the fasting requirement.

METHODOLOGY: 

• Between April 14, 2023, and October 7, 2023, 410 patients taking LT4 from a Dutch outpatient internal medicine clinic completed questionnaires regarding their experiences and feelings (of a total 463 invited).

TAKEAWAY:

• Of the total 410 patients, 89.5% reported receiving fasting instructions, ie, to wait 30-60 minutes after taking LT4 before eating breakfast.
• While 67.1% reported adhering to the instruction, 22.4% took LT4
• Two thirds (60.5%) reported preferring ingestion together with breakfast.
• Nearly half (49.5%) reported feeling burdened with the need to postpone breakfast, rating the burden with a median score of 7 on a Likert scale from 0 (no burden) to 10 (severe burden).
• One quarter (24.9%) reported omitting breakfast and 13.4% reported forgetting their medication.
• One third (33.7%) reported using other medications that potentially interfere with LT4 (such as certain vitamins/supplements, proton pump inhibitors, and H2 receptor antagonists).
• Of those 85 patients using interfering medications, only 31.8% (n = 27) reported being told to maintain a 4-hour interval between taking them and LT4, and of those 27, fewer than half (n = 11) adhered to that.
• There was a statistically significant association between non-fasted LT4 ingestion and use of co-medication (odds ratio, 2.82; P 1 year (1.76; P = .04), and male sex (1.67; P = .04).

IN PRACTICE:

“Our study highlights the significant challenges and burdens associated with postponing breakfast to adhere to the current recommendation for fasting LT4 ingestion, leading to non-adherence, irregular LT4 intake and omitting breakfast with potential adverse effects on [quality of life] and cardiovascular health. Given the clear preferences towards LT4 ingestion together with breakfast, further research into alternative non-fasting administration methods without compromising treatment efficacy is warranted,” the authors wrote.

SOURCE:

Conducted by Jeresa I.A. Willems, MD, of the Department of Internal Medicine, Zuyd Thyroid Center, Zuyderland Medical Center, Sittard/Heerlen, the Netherlands, and colleagues, the study was published online October 21, 2024, in the Journal of the Endocrine Society.

LIMITATIONS:

Potential selection bias of survey respondents. Some patients may have forgotten about received instructions.

DISCLOSURES:

There was no funding for this work and the investigators have no disclosures.