Pituitary Hyperplasia Secondary to Prolonged Undiagnosed Hypothyroidism in a 13-Year-Old Female

Abstract Pituitary hyperplasia is often overlooked as a potential complication of chronic hypothyroidism. When hypothyroidism persists, the disruption of the negative feedback loop from the thyroid can lead to increased thyrotropin production in the pituitary, resulting in hyperplasia. This case report aims to explore pituitary hyperplasia as a reversible complication of untreated primary hypothyroidism, highlighting the importance of timely diagnosis and appropriate treatment to prevent unnecessary interventions. We reported a 13-year-old female presented with psychosis, crying spells, and emotional instability, which led to an initial psychiatric evaluation. Laboratory tests revealed severely elevated thyroid-stimulating hormone (TSH) levels greater than 100 mIU/L, low free thyroxine (T4) levels at 0.1 ng/dL, and high thyroid peroxidase antibodies (> 600 IU/mL), confirming a diagnosis of Hashimoto's thyroiditis and severe primary hypothyroidism. A pituitary magnetic resonance imaging showed signs of pituitary hyperplasia. Following the initiation of levothyroxine therapy, the patient's TSH levels normalized, and the pituitary hyperplasia significantly regressed. The patient has since remained stable and asymptomatic. This case report details a 13-year-old female diagnosed with Hashimoto's thyroiditis and pituitary hyperplasia. Following levothyroxine treatment, both thyroid function and pituitary size normalized, leading to significant clinical improvement. This case highlights the importance of recognizing pituitary hyperplasia as a reversible condition caused by hypothyroidism. It underscores the critical need for timely diagnosis and appropriate treatment to prevent unnecessary surgical interventions.