Thyroid Function in Patients with Cystic Fibrosis: No Longer a Concern?

Area of Science:

• Endocrinology
• Pulmonology
• Medical Research

Background:

• Thyroid dysfunction, including goiter and hypothyroidism, was previously observed in cystic fibrosis (CF) patients, particularly with iodine-based expectorants.
• The prevalence of thyroid dysfunction in current CF populations is unknown due to the decline in routine use of iodine-containing expectorants.

Purpose of the Study:

• To assess the current thyroid function status in a large cohort of cystic fibrosis patients.
• To identify potential predictors of thyroid dysfunction in individuals with CF.

Main Methods:

• A cross-sectional study analyzed sera from 89 ambulatory and hospitalized CF patients.
• Thyroid function tests (TSH, fT4) were measured, and data on demographics, FEV1, and medications were collected.
• Multivariate regression models were used to assess associations between covariates and thyroid function parameters.

Main Results:

• Eight percent of subjects had abnormal TSH levels, and 34% had slightly low free thyroxine (fT4), with 17 cases of isolated mild hypothyroxinemia.
• No significant predictors (age, sex, BMI, FEV1, hospitalization, medication use, TPO antibodies) were identified for TSH, fT4, or thyroid dysfunction.
• A positive correlation was noted between age and BMI, and a negative correlation between age and FEV1.

Conclusions:

• Overt thyroid dysfunction was rare in this cohort of 89 CF patients, although 27% exhibited abnormal thyroid function tests.
• Marginal hypothyroxinemia was observed, potentially linked to nonthyroidal illness rather than primary thyroid disease.
• No significant predictors for thyroid dysfunction were found in this CF population.