The study, “Iodine deficiency and subclinical hypothyroidism are common in cystic fibrosis patients,” was published online ahead of print in October 2012. It appears in the Journal of Trace Elements in Medicine and Biology.
The study authors hypothesized that an association may exist between CF and thyroid disorders because of the iodine deficiency that occurs in many patients with CF. They argue that a lack of iodine might be responsible for problems with thyroid function.
To test this hypothesis, the researchers examined data on 129 people (children, adolescents, and adults) who were living with CF. All of the participants lived in the northern portion of Bavaria/Germany. Data was collected about participants’ lung function and their levels of malnutrition. Additionally, the researchers examined the patients’ urinary iodine excretion, thyroid-stimulating hormone (TSH), and free thyroxine (fT4). These indicators were measured in relation to a set of population-based, age-adjusted references.
The results of the study showed that subclinical hypothyroidism (defined as having normal fT4 and elevated TSH) was found in 11.6% of the study participants. Additionally, 83.7% of the patients were found to have iodine deficiency. The researchers did not find any correlations with the participants’ age, malnutrition level, lung function, or body mass index.
The researchers conclude that their study results demonstrate significant iodine deficiency in their sample of patients with cystic fibrosis. They argue that abnormally low levels of iodine can lead to subclinical hypothyroidism and that some patients with CF may require iodine supplementation to assist with thyroid function.