Acquired von Willebrand syndrome type 1 in hypothyroidism: Reversal after treatment with thyroxine

In 16 cases, acquired von Willebrand syndrome (AvWS) and hypothyroidism hav e been described that occur with each other: 15 women and one man, at a mea n age of 32 years, range, 13 to 82 years of age. Activated partial thrombop lastin time (APTT) was normal in six patients, and five patients had factor VIII concentration (factor VIIIc) levels in excess of 60%. The bleeding ti me was prolonged in nine of 13 evaluable patients. Activated partial thromb oplastin time was prolonged in seven patients, and five of these had factor VIIIc levels between 18 and 45%, with two patients having levels in excess of 60%. A deficiency of other coagulation factors, including factor VII, V , IX, and X, caused by a generalized diminution in protein synthesis in hyp othyroidism, may have contributed to the prolongation of the APTT. The AvWS was very likely type 1 in all cases because of a normal von Willebrand fac tor antigen/ristocetin cofactor (vWF Ag/RCF) ratio. Acquired von Willebrand syndrome was documented via cross immunoelectrophoresis in three patients and via multimeric analysis of vWF in six patients. A definite diagnosis of AvWS type I has to be confirmed by a normal response to 1-desamino-8-D-arg inine vasopressin (DDAVP). Treatment of hypothyroidism with thyroxine was a ssociated with the disappearance of the AvWS and the bleeding diathesis. De creased factor VIIIc, vWF Ag and vWF RCF levels (50%, 33%, and 36% respecti vely) before thyroxine treatment increased to normal values (97%, 93%, and 107% respectively) after treatment. The absence of bleeding, or mild bleedi ng, symptoms, in relation to those more commonly recognized with hypothyroi dism, has led to the complication of acquired vWF deficiency being underdia gnosed. Acquired von Willebrand syndrome type I should be considered whenev er hypothyroidism is diagnosed and thyroid biopsy or surgery is contemplate d. The complete relief of AvWS via treatment of hypothyroidism with thyroxi ne is the final proof of this association and causal relationship.