Severe primary hypothyroidism and ovarian hyperstimulation syndrome in a spontaneous pregnancy: a case report

Background: Ovarian hyperstimulation syndrome (OHSS) is a rare ovulation induction therapy side effect. Nevertheless, it can occur in spontaneous ovulation cycles linked to multiple gestation, molar pregnancy, polycystic ovarian syndrome, and hypothyroidism. The pathogenesis of OHSS remains poorly understood. However, in recent studies, it has been observed that increased concentrations of thyroid-stimulating hormone (TSH) can potentially have stimulatory effects on the ovaries due to the homologous structure shared between TSH and gonadotropins. It is recommended to delay pregnancies until euthyroidism is achieved with replacement therapy to reduce potentially fatal problems. Case Description: We describe the case of a 22-year-old female patient who sought medical attention due to a 4-week history of abdominal discomfort and amenorrhea. Upon evaluation, it was determined that she was in the 9th week of pregnancy and experiencing OHSS due to severe primary hypothyroidism. The diagnosis was confirmed through laboratory and imaging data, enabling timely care and preventing complications arising from unwarranted surgical intervention. Administration of levothyroxine led to total regression of the ovarian cysts. Even so, the patient decided to terminate her pregnancy. Conclusions: This case illustrates the occurrence of OHSS in a woman with untreated hypothyroidism. Notably, this syndrome is relatively uncommon, and the patient's ability to conceive while having unviable thyroid hormone levels further adds to this case's exceptional nature.