Autoimmunity puzzle in Down syndrome

One of the most common genetic abnormalities, Down syndrome is associated with intellectual disabilities as well as increased incidence of autoimmune diseases. Endocrine disorders, such as diabetes and thyroid dysfunction are amongst the most common. We describe the case of a 27 year old woman diagnosed with diabetes at the age of 9, who had associated crises of loss of consciousness from the age of 23 and developed primary autoimmune hypothyroidism from the age of 25 years with chronic pericardial effusion. Neurological examination considered the diagnosis of absence crises; therefore she started taking Carbamazepine 400 mg daily since the age of 23. At admission, the patient was obese (BMI =32 kg/m2), with neck localised acanthosis nigricans. The clinical examination revealed signs of hypothyroidism without goitre. Diagnosis was confirmed by TSH = 350 mUI/L, anti TPOAb = 329.9 U/ml as well as pericardial effusion on echocardiography. She started thyroxine replacement therapy, while being on basal/bolus insulin regimen (short and intermediate acting insulin). Full control of diabetes was not achieved until she also received metformin and basal insulin analog. TSH level reached normal values of 2.4 mU/L only after a LT4 substitution dose of 150 µg daily. Evolution of thyroid status and diabetes under progressive thyroxine substitutive treatment is discussed. Compliance to diet, diabetes and myxoedema treatment is severely influenced by her intellectual disabilities. Screening for thyroid status and autoimmunity in order to detect subclinical hypothyroidism, should be performed in patients with Down syndrome.