RESUMO
Pituitary stalk interruption syndrome (PSIS) manifests as an isolated or combined pituitary hormone deficiency (CPHD) and is usually diagnosed by magnetic resonance imaging (MRI). We describe a patient with PSIS who presented with central hypothyroidism. The patient was born at 35 weeks’ gestation and weighed 1,980 g. Newborn screening test including thyroid-stimulating hormone (TSH) were normal; however, follow-up tests revealed low serum free thyroxine and mildly elevated TSH levels. Thyroid hormone replacement was initiated on the 29th day of birth. At 13-month-old age, the TRH stimulation test showed a delayed and prolonged increase in serum TSH levels, suggesting tertiary hypothyroidism. The combined pituitary stimulation test revealed CPHD and hyper-responsiveness of prolactin to TRH, suggesting hypothalamic-pituitary disconnection. MRI of the pituitary gland revealed the absence of the pituitary stalk, a small anterior pituitary, and an ectopic posterior pituitary located in the hypothalamic area. Replacement therapies with corticosteroid and growth hormone were initiated and then she reached catch-up growth. The TRH stimulation test can be helpful for diagnosing central hypothyroidism, which may be an early presentation of PSIS. Therefore, patients with central hypothyroidism should be considered for PSIS, thereby patients can be treated earlier and reach normal growth and development.