RESUMEN
BACKGROUND: Delayed diagnosis of hypothyroidism may result in atypical presentations. Here, we report a case with decreased serum level and activity of von Willebrand factor due to untreated profound hypothyroidism. OBSERVATION: A 9-year-old girl, presented with prolonged gingival bleeding after dental extraction. Clinical findings of the case were consistent with hypothyroidism, and the laboratory workup results revealed decreased serum level and activity of von Willebrand factor associated with profound hypothyroidism. Restoration of euthyroidism normalized the coagulation parameters. CONCLUSION: Delayed diagnosis of hypothyroidism may lead to atypical presentations such as bleeding diathesis. Profound hypothyroidism should be considered in the differential diagnosis of acquired von Willebrand disease to avoid undue treatment.