# Severe Primary Hypothyroidism in a Child Presenting as a Pituitary Tumour: A Case Report

## TL;DR

A child with severe hypothyroidism was initially misdiagnosed with a pituitary tumor, but symptoms resolved after thyroid hormone treatment.

## Contribution

This case highlights the importance of checking thyroid function before pituitary surgery in children.

## Key findings

- Severe hypothyroidism can mimic a pituitary tumor due to pituitary hyperplasia.
- Levothyroxine therapy reversed pituitary hyperplasia in this patient.
- Thyroid function testing is crucial to avoid unnecessary pituitary surgery in children.

## Abstract

Primary hypothyroidism in children often manifests as short stature, and if untreated, it can result in pituitary hyperplasia due to chronic thyrotropin-releasing hormone (TRH) drive resulting from the loss of negative feedback by low circulating thyroid hormones, potentially leading to unnecessary surgery. We report the case of a nine-year-old patient with a persistent headache with a suspected diagnosis of a pituitary mass. Blood tests revealed severe hypothyroidism (extremely elevated thyroid-stimulating hormone (TSH) and suppressed free thyroxine (T4). The initial MRI led to a misdiagnosis of pituitary adenoma. Reversible pituitary hyperplasia completely regressed following levothyroxine therapy. This case highlights the relevance of considering hypothyroidism when evaluating pituitary masses. Thyroid function should always be assessed before considering pituitary surgery in children.