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

Summary 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-T4). 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-T4. 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-T4 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-T4. Ultrasound follow-up shows normal ovarian size with complete resolution of ovarian cysts 4 months after treatment.


Background
Ovarian hyperstimulation syndrome (OHSS) is usually iatrogenic and is a potentially life-threatening complication of ovulation induction. Spontaneous OHSS might occur following high levels of human chorionic gonadotropin (HCG) in normal pregnancy, hypothyroidism, or FSH receptor mutation (1). Expanding use of ultrasonography facilitates the diagnosis and monitoring of the treatment of this syndrome (2).
We have described this syndrome in a girl virgin with primary autoimmune hypothyroidism in our previous article (3); we followed her by serial abdominal ultrasound that showed normal ovary size and regression of ovarian cysts after levothyroxine (L-T 4 ) replacement.

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 (3). The abdomen was distended and non-tender with a large palpable mass in the lower abdomen extending to the upper abdomen.

Treatment
She was started on L-T 4 100 mg/day.

Outcome and follow-up
On follow-up ultrasound, the size of the ovaries became significantly smaller 6 weeks after L-T 4 replacement and became normal with complete resolution of cysts after 4 months (Figs 1 and 2).

Discussion
A description of OHSS in two members of a family has recently been published (3), but there are a few studies focusing on ovarian volume and cyst regression after L-T 4 replacement therapy. Imaging findings in OHSS include multiple, large, and thin-walled cysts and ascitic fluid in severe forms (4). The exclusion of diagnosis of ovarian cancer is made by ultrasonography and CT scan or magnetic resonance imaging (MRI), which reveals the classical 'spoke wheel' appearance that is characteristic of theca lutein cysts without solid components. Furthermore, the reduction in ovarian volume and regression of detected cysts during close observational management and ultrasonic follow-up can differentiate OHSS from other diagnoses (5).
Here, we described resolution of ovarian cysts and normalization of the size of the ovaries in our patient 4 months after L-T 4 administration (Fig. 3). It is noteworthy that the kinetics of the symptoms are closely related to the life span of corpus luteum. In the absence of pregnancy, symptoms resolve spontaneously with the onset of menses, while in the presence of pregnancy, symptoms start to improve after the sixth week of pregnancy, before HCG peak (1). However, in OHSS with underlying disease such as hypothyroidism, complicated pregnancies or in the presence of mutated FSH receptor genes, the symptoms have been reported to last longer (6) (7) (8) (9) (10) (11) (12) (13) (14). Mousavi et al. (6) reported normalization of ovarian appearance in ultrasound 6 months after L-T 4 replacement therapy. In other studies on hypothyroid patients (with and without pregnancy), considerable regression of cysts was observed after 3 months (7) (8) (9) (10) (11), with an exception that in three case reports patients experienced total regression 3 months after delivery (12) (13) (14)  endogenous HCG might strengthen the severity of OHSS in pregnant patients and would lead to a more complicated course than patients with hypothyroidism (15).
In conclusion, ultrasonography as well as CT scan or MRI assists the diagnosis of OHSS. By serial ultrasound, we observed regression of ovarian cysts and ovarian volume after 4 months whereas in other studies, it is reported to happen in various durations that may be related to the etiology of this syndrome.