Background: Chronic autoimmune thyroiditis is a nosological entity with a lot of genetic and extrinsic predisposing factors. Females are more exposed than males (3-5:1) with a greater incidence in the age of 20 (10-15%) and in middle age (>55 y) in a percentage of 30-33%. The main characteristic of the disease is high levels of antithyroid antibodies in blood in a percentage of 90% of patients and only 10% of them are affected by a subclinical hypothyroidism .
Methods: A 32 years old man, foreigner, prisoner, smoker (25 p/y) is at the last (9th) month of treatment with HR (2HRZE/7HR) due to pulmonary tuberculosis. He reveals generalized edema particularly expressed on his face, hands and inferior extremes. He refers fatigue and appeared hoarseness, psychical rallentation, dry and rough skin, loss of hair while tumefaction, semisolid consistence and abnormal structure of thyroid gland. Pulmonary auscultation reveals rales and crackles at the upper lobes while bradycardia (HR: 50 bpm) is confirmed in both auscultation and electrocardiogram. He also reveals high levels of inflammation indexes and antithyroid antibodies, decreasing of T3, T4, fT3, fT4 and increasing of Thyroid-stimulating hormone (TSH), alteration of liver biochemical tests, hypercholesterolemia, hyperproteinemia, elevated creatine phosphokinase (CPK), anemia, parameters that are emerged by the biochemical exams (normal profile before nine months).
Results: Thyroid gland ultrasound demonstrated a diffused micro nodular heterogenity of both lobes. On the contrary, abdomen and heart ultrasound appeared normal. The patient was submitted for a thyroid Fine-needle aspiration biopsy (FNA) (ultrasound guided) followed by negative results of fast acid bacili test and β-koch culture of the bioptic material, excluding the thyroid TBC and confirming the diagnosis of autoimmune thyroiditis induced by rifampicin. Patient received levothyroxine, the antitubercular therapy was completed with a following melioration in both of clinical appearance and thyroid hormone levels tests.
Discussion: Based in bibliography, levels of thyroid hormones and antibodies in healthy subjects are rarely influenced by rifampin, inducing liver microsomal enzyme activity due to an unknown mechanism. Lots of studies in animals are trying to interpret it. Maybe a recommendation for our diagnostic procedures will be the control of thyroid hormones and antithyroid antibodies as a protocol, before the somministration of antitubercular drugs.
