Pituitary Macroadenoma and Severe Hypothyroidism: The Link between Brain Imaging and Thyroid Function

Area of Science:

• Pediatric Endocrinology
• Neuroendocrinology
• Radiology

Background:

• Primary hypothyroidism can lead to reactive pituitary hyperplasia, potentially presenting as a pituitary macroadenoma.
• This condition can cause growth hormone deficiency, impacting growth velocity and body weight in children.

Observation:

• A 12-year-old boy presented with impaired growth and increased weight, exhibiting low insulin-like growth factor 1 levels.
• Brain MRI revealed a pituitary macroadenoma, initially suspected as the cause of growth hormone deficiency.

Findings:

• Initiation of levothyroxine therapy for hypothyroidism led to a significant decrease in pituitary mass size.
• Growth hormone secretion normalized, and the pituitary gland returned to normal size within approximately 5 years.
• The patient achieved normal adult height and underwent spontaneous puberty.

Implications:

• This case highlights that reactive pituitary hyperplasia in primary hypothyroidism can mimic pituitary macroadenoma in children.
• Accurate hormonal evaluation is crucial for correct diagnosis, preventing unnecessary surgical intervention for pituitary masses.
• Levothyroxine treatment is effective in resolving hyperplasia and normalizing endocrine function in such cases.