Cyclic thrombocytopenia is a
rare disease characterized by cyclic oscillations of platelet counts from very low to normal or higher. Severe
hemorrhage may occur during the thrombocytopenic phase. To date, treatments for this disorder have been disappointing. Its pathophysiology is unknown. We report a successful outcome using
danazol therapy. Prior to
danazol treatment, the patient had
a 7 year history of
cyclic thrombocytopenia, refractory to
glucocorticoids,
splenectomy,
azathioprine,
vinca alkaloids, plasma infusions, and hormonal manipulation with
Premarin-
Provera. Her platelet counts were found to be oscillating in a 21 day cycle between 1 x 10(9)/L and 500 x 10(9)/L. Platelet-associated
antibodies were positive and
chromium-labeled platelet survival time was shortened. Following 2 months of
danazol therapy, her platelet counts at the nadirs were significantly higher than at previous nadirs, and at no time thereafter dropped to the critically low values seen before
danazol. Also at 2 months of
danazol treatment, the patient reported amelioration of
petechiae, and at 9 months it was completely cleared. However, platelet-associated
IgG remained positive and platelet counts continued to oscillate, typically between 100 x 10(9)/L and 300 x 10(9)/L in the second year, but stabilized at 3 years, when platelet-associated
IgG also disappeared.
Danazol was discontinued after 3.5 years. The patient remains in unmaintained remission today, approximately 5 years after discontinuance of
danazol. It can be argued that the long-term outcome was due to spontaneous remission. However, significant improvement was noted from the outset of
danazol therapy, and further improvement with long-term
therapy, as seen in the response of chronic
ITP to
danazol therapy.
Danazol may offer lasting benefit in
cyclic thrombocytopenia.