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Zorluk: OrtaPediatric Endocrine Disorders

A 12-year-old boy is brought to the pediatric endocrinology clinic by his parents due to poor growth and increasing fatigue over the past 12 months. He used to be energetic but now frequently falls asleep in class. He also complains of feeling cold, even during the summer, and reports new-onset frequent morning headaches. Over the past year, his height has plateaued, falling from the 50th percentile to below the 10th percentile. Physical examination reveals a pale, prepubertal boy with dry skin and delayed relaxation phase of deep tendon reflexes. Visual field testing by confrontation reveals diminished peripheral vision bilaterally. Which of the following serum laboratory patterns is most likely present in this patient?

  1. Decreased thyroid-stimulating hormone (TSH) and decreased free thyroxine (T4)Cevap
  2. B
    Elevated TSH and decreased free T4
  3. C
    Decreased TSH and elevated free T4
  4. D
    Elevated TSH and elevated free T4
  5. E
    Normal TSH, normal free T4, and decreased free triiodothyronine (T3)

Cevap

Decreased thyroid-stimulating hormone (TSH) and decreased free thyroxine (T4)
The correct answer is a pattern of decreased TSH and decreased free T4. This patient's clinical presentation (fatigue, cold intolerance, poor growth, delayed reflexes) is highly suggestive of hypothyroidism. However, the addition of morning headaches and bitemporal hemianopsia (loss of peripheral vision) points to a mass effect in the sellar or suprasellar region. In the pediatric population, a craniopharyngioma is a common culprit. A mass in this region compresses the optic chiasm (causing the visual defect) and disrupts the hypothalamic-pituitary axis, leading to panhypopituitarism. The lack of TSH stimulation from the pituitary results in decreased free T4 production from the thyroid gland, defining central (or secondary) hypothyroidism.

Adım Adım Çözüm

1
Analyze the patient's systemic symptoms.
Symptoms include fatigue, cold intolerance, dry skin, delayed deep tendon reflexes, and growth failure.
These findings are classic clinical manifestations of hypothyroidism in a pediatric patient.
2
Analyze the patient's focal neurological symptoms.
The patient has morning headaches and loss of bilateral peripheral vision (bitemporal hemianopsia).
These specific neurological findings strongly suggest a compressive mass in the sellar/suprasellar region, such as a craniopharyngioma, affecting the optic chiasm and raising intracranial pressure.
3
Synthesize findings to determine the most likely underlying pathology and predicted lab values.
A pituitary/hypothalamic mass compressing normal pituitary tissue causes central (secondary) hypothyroidism. This results in decreased production of TSH, leading to a subsequent decrease in free T4 production by the thyroid gland.
Understanding the hypothalamic-pituitary-thyroid axis is essential to correlate central structural lesions with their expected hormonal deficits.

Anahtar Kavram

Central hypothyroidism due to a compressive sellar mass (like craniopharyngioma) presents with hypothyroid symptoms alongside neurological signs (headaches, bitemporal hemianopsia) and is characterized by low or inappropriately normal TSH with low free T4.
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Pediatric Endocrine Disorders

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