ESPE Abstracts

In children, autoimmune thyroiditis is often diagnosed with signs and symptoms such as goiter, short stature, and constipation. Delayed diagnosis of hypothyroidism may result in atypical signs and symptoms at presentation, depending on the severity of hypothyroidism. Von Willebrand disease (vWD) is the most common bleeding disorder caused by the quantitative or qualitative deficiency of von Willebrand factor (vWF). Acquired vWD (avWD) is a disorder characterized by low levels of vWF due to reduced production and/or enhanced removal of vWF from the circulation. It is distinguished from inherited vWD by a lack of prior history of bleeding diathesis in the index case and a negative family history of vWD. Herein, we report a case with acquired vWD due to delayed diagnosis of hypothyroidism due to autoimmune thyroiditis.

Case report: A 9-year-old, prepubertal girl was referred to our pediatric hematology outpatient clinic owing to prolonged gingival bleeding after dental extraction. Past medical history was unremarkable. The physical examination revealed pallor, facial swelling, periorbital puffiness, dry skin and grade 1b guatr. She was 130 cm (-0.54 SDS) tall and body mass index was 21.8 kg/m2 (1.71SDS). The remaining systems’ examination yielded normal findings. Coagulation profile revealed normal platelet count, prothrombin time, activated partial tromboplastin time (APTT), fibrinogen. Additional laboratory work-up revealed macrocytic anaemia (haemoglobin: 9.8 g/dl, MCV:93fL), and severe primary hypothyroidism (fT4: 0,79 ng/dl, TSH:697mU/L). Thyroid autoantibodies were positive and thyroid ultrasound confirmed thyroiditis. In literature, avWD due to hypothyroidism have been reported in children. Although APTT level was normal, we also found decreased levels of factor VIII (74% [N:60-150]), vWF antigen (56.6% [N:50-160) and vWF ristocetin cofactor activity (51% [N: 50-200]) in our case, suggestive of aVWD. Substitution therapy with levothyroxine was initiated. Prolonged bleeding did not recur after commencement of L-T4 treatment. The levels of factor VIII (107%), vWF antigen (132%) and vWF ristocetin cofactor activity (68%) were normalized and macrocytic anemia resolved at the fourth month of L-T4 treatment.

Conclusion: Delayed diagnosis of acquired primary hypothyroidism may lead to atypical signs and symptoms. Patients with bleeding diathesis of unknown origin should also be investigated for hypothyroidism. The pathophysiology of avWD in hypothyroidism is not clear, but it is hypothesized that there is a reduction in the synthesis of Factor VIII and vWF. The increase in levels of Factor VIII and vWF in our case in parallel with normalization of thyroid functions also support this hypothesis.