Pituitary Hyperplasia from Primary Hypothyroidism

A 10 yearold girl presented with headaches and poor growth, accompanied by clinical findings of dry skin and growth below the third percentile for height. Laboratory tests revealed markedly elevated thyrotropin levels (>150 µU/mL) and low free thyroxine (0.4 ng/dL), consistent with primary hypothyroidism. Magnetic resonance imaging (MRI) identified a diffusely enhancing sellar lesion extending to the optic chiasm, indicative of pituitary hyperplasia secondary to untreated hypothyroidism. Treatment with levothyroxine resulted in resolution of symptoms, normalization of thyrotropin levels, and a 6 cm growth in height over 10 months. Follow up MRI confirmed the regression of pituitary enlargement. This case underscores the importance of recognizing pituitary hyperplasia as a reversible consequence of long standing primary hypothyroidism and highlights the efficacy of thyroid hormone replacement therapy in restoring normal pituitary morphology and function.

A 10 yearold girl presented with headaches and poor growth, accompanied by clinical findings of dry skin and growth below the third percentile for height. Laboratory tests revealed markedly elevated thyrotropin levels (>150 µU/mL) and low free thyroxine (0.4 ng/dL), consistent with primary hypothyroidism. Magnetic resonance imaging (MRI) identified a diffusely enhancing sellar lesion extending to the optic chiasm, indicative of pituitary hyperplasia secondary to untreated hypothyroidism. Treatment with levothyroxine resulted in resolution of symptoms, normalization of thyrotropin levels, and a 6 cm growth in height over 10 months. Follow up MRI confirmed the regression of pituitary enlargement. This case underscores the importance of recognizing pituitary hyperplasia as a reversible consequence of long standing primary hypothyroidism and highlights the efficacy of thyroid hormone replacement therapy in restoring normal pituitary morphology and function.