Abnormal thyroid function: an unusual presentation of pituitary stalk interruption syndrome

Area of Science:

• Pediatric Endocrinology
• Neuroendocrinology
• Rare Diseases

Background:

• A previously healthy 11-year-old girl presented with pallor, initially found to have low free thyroxine (T4) and normal thyroid-stimulating hormone (TSH).
• Subsequent evaluation revealed a pattern suggestive of primary hypothyroidism, but with a TSH level disproportionately low for the degree of free T4 reduction.

Purpose of the Study:

• To investigate the cause of central hypothyroidism in a pediatric patient.
• To highlight the diagnostic approach for pituitary stalk interruption syndrome (PSIS).

Main Methods:

• Clinical evaluation and repeated laboratory testing including thyroid function tests.
• Multi-pituitary hormone assessment.
• Magnetic Resonance Imaging (MRI) of the pituitary region.

Main Results:

• Laboratory studies and MRI confirmed panhypopituitarism secondary to pituitary stalk interruption syndrome.
• The patient was clinically euthyroid despite biochemical evidence of hypothyroidism, indicating central origin.

Conclusions:

• Pituitary stalk interruption syndrome is a critical cause of panhypopituitarism in children.
• Central hypothyroidism requires a high index of suspicion in cases of low free T4 with an incongruous TSH level.
• Comprehensive pituitary hormone assessment and MRI are essential for diagnosing PSIS.