Isolated Central Hypothyroidism in an Adolescent With Narcolepsy

Area of Science:

• Pediatric Endocrinology
• Neurology
• Sleep Medicine

Background:

• Isolated central hypothyroidism (ICH) and narcolepsy are uncommon pediatric conditions often presenting with subtle, delayed-diagnosis symptoms.
• Both conditions can manifest with excessive daytime sleepiness and fatigue, complicating differential diagnosis.

Observation:

• A 15-year-old male presented with excessive daytime sleepiness, fatigue, and snoring, initially suspected as obstructive sleep apnea (OSA).
• Sleep studies ruled out OSA but indicated narcolepsy without cataplexy. Modafinil treatment was ineffective.
• Subsequent thyroid function tests revealed ICH, and thyroid replacement therapy led to symptom improvement.

Findings:

• This case presents a rare clinical association between narcolepsy and ICH in an adolescent.
• Narcolepsy without cataplexy shares overlapping symptoms with hypothyroidism, potentially masking or mimicking each other.

Implications:

• The hypothalamus and pituitary gland's involvement suggests a theoretical link between narcolepsy and ICH.
• Clinical vigilance for ICH is warranted in pediatric patients diagnosed with narcolepsy, given the shared symptomatology.
• Screening for hypothyroidism should be considered in adolescents presenting with narcolepsy symptoms.