Thyroid disease is a common endocrine disorder. Oral lichen planus (OLP) is a chronic autoimmune disease that occurs on the oral mucosa in 1-2% of the general population.The purpose of this study was to determine whether there is an association between thyroid disease and oral planus lichen in the population of our patients. In the last few years, a couple of studies have been published in the world literature that have studied the possible association of these diagnoses in different populations. Most of the results showed a higher prevalence of thyroid disease in the population of lichen patients, compared with patients without lichen, although some results are contradictory. Some authors believe that the onset of OLP precedes thyroid dysfunction. In the population of Croatian patients with lichen, no research has been done to study the possible connection between these two diseases. The obtained results could help clarify whether there is a connection between these two diagnoses in the population of our lichen patients and enable earlier detection of patients with thyroid hypofunction.

Inclusion Criteria:

• for test group: female patients of the Department of Oral Medicine School of Dental Medicine University of Zagreb with clinically and histopathologically confirmed oral lichen planus
• for control group: female patients of the Department of Oral Medicine School of Dental Medicine University of Zagreb, without oral lichen planus or other immune disorders; age matched to test group

Exclusion Criteria:

• male patients; female patients with immune disorders; female patients which are not age-matched to test group

Oral lichen planus and thyroid diseases are more frequent in female gender. We wanted the groups to be as similar in characteristics as possible so we included only females.

The study included female patients of the Department of Oral Medicine, age matched, with oral lichen planus and without oral lichen planus or other immune disorders. All patients included in the study made blood test and the results were analyzed with statistical methods.