Two different entities of spontaneous ovarian hyperstimulation in a woman with FSH receptor mutation.

Spontaneous ovarian hyperstimulation syndrome (OHSS) is an extremely rare event. Normally OHSS is seen in the context of IVF. In 2003 a mutation of the FSH receptor (FSHR D567N) was identified for the first time as a cause of spontaneous OHSS. In most FSHR mutations, a hypersensitivity to human chorionic gonadotrophin (HCG) or thyroid-stimulating hormone (TSH) is described. This clinical case presents for the first time two occurrences of spontaneous OHSS in a single woman with a FSHR mutation and two different entities. Pathophysiology of both pregnancies was completely different. During the first pregnancy, elevated HCG and androgen concentrations led to spontaneous OHSS and finally to miscarriage. The second pregnancy with spontaneous OHSS was dominated by a latent hypothyroidism and normal HCG concentrations and ended in a delivery of a healthy female newborn. Due to the unusual courses of the pregnancies, the study looked for a mutation in the FSHR and surprisingly identified the same mutation previously described. This report confirms for the first time the in-vitro findings in a single clinical case that TSH as well as HCG leads to spontaneous OHSS in patients with FSHR D567N mutation. Hypothyroidism has to be treated or ruled out.