Ovarian cyst regression with levothyroxine in ovarian hyperstimulation syndrome associated with hypothyroidism

Background: Spontaneous ovarian hyperstimulation syndrome (sOHSS) can occur following hypothyroidism. Ultrasonography facilitates diagnosis and monitoring of this syndrome. We describe ovarian sonographic changes in a hypothyroid patient with sOHSS after treatment with levothyroxine (l-T(4)). Case presentation: A 15-year-old girl presented with abdominal pain and distension for a few months. On examination, she had classical features of hypothyroidism. Abdominal and pelvic ultrasound revealed enlarged ovaries with multiple thin-walled cysts and mild ascitic fluid. On follow-up, abdominal ultrasound showed significant reduction of ovary size after 6 weeks of initiation of l-T(4). Normal ovary size with complete regression of ovarian cysts was seen after 4 months. Conclusion: Serial ultrasound in sOHSS associated with hypothyroidism showed regression of ovarian cysts and ovarian volume after 4 months whereas in other studies, it is reported to happen in various durations, presumably according to its etiology. LEARNING POINTS: OHSS can rarely occur due to hypothyroidism. This type of OHSS can be simply treated by l-T(4) replacement, rather than conservative management or surgery in severe cases. Ultrasound follow-up shows significant regression of ovarian size and cysts within 6 weeks of initiation of l-T(4). Ultrasound follow-up shows normal ovarian size with complete resolution of ovarian cysts 4 months after treatment.