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Zorluk: ZorPediatric Endocrine Disorders

A 9-year-old boy is brought to the clinic for evaluation of poor growth. Over the past 2 years, his height has decreased from the 50th to the 5th percentile, while his weight has increased from the 50th to the 75th percentile. The patient also complains of being constantly tired, feeling cold, and waking up 3 to 4 times a night to urinate and drink water. He has no significant past medical history. His temperature is 36.2∘C36.2^\circ\text{C}, blood pressure is 90/60 mmHg90/60\text{ mmHg}, and pulse is 58/min58/\text{min}. Physical examination shows dry skin and delayed relaxation of the deep tendon reflexes. He is at Tanner stage 1 for pubic hair and genital development.

Laboratory results are as follows:

TestResultReference Range
Serum sodium149 mEq/L149\text{ mEq/L}135−145 mEq/L135-145\text{ mEq/L}
Serum osmolality312 mOsm/kg H2O312\text{ mOsm/kg H}_2\text{O}275−295 mOsm/kg H2O275-295\text{ mOsm/kg H}_2\text{O}
Urine osmolality140 mOsm/kg H2O140\text{ mOsm/kg H}_2\text{O}>800 mOsm/kg H2O>800\text{ mOsm/kg H}_2\text{O} (with water deprivation)
Thyroid-stimulating hormone (TSH)0.2 \muU/mL0.2\text{ \mu U/mL}0.5−5.0 \muU/mL0.5-5.0\text{ \mu U/mL}
Free thyroxine (T4)0.6 ng/dL0.6\text{ ng/dL}0.9−2.3 ng/dL0.9-2.3\text{ ng/dL}

Which of the following is the most likely etiology of this patient's current condition?

  1. A
    Autoimmune destruction of thyroid follicular cells
  2. Cystic epithelial tumor arising from Rathke pouch remnantsCevap
  3. C
    Defective organification of iodide in the thyroid gland
  4. D
    Delayed maturation of the hypothalamic-pituitary axis
  5. E
    Reduced sensitivity of the renal collecting ducts to antidiuretic hormone

Cevap

The most likely etiology is a cystic epithelial tumor arising from Rathke pouch remnants (craniopharyngioma).
The patient presents with signs of acquired hypothyroidism (fatigue, cold intolerance, weight gain, bradycardia, poor growth) and diabetes insipidus (polyuria, polydipsia, hypernatremia, dilute urine). The laboratory profile confirms central hypothyroidism (low free T4 and inappropriately low TSH) and diabetes insipidus. A lesion affecting both the pituitary and hypothalamus is necessary to cause this combination of findings. In children, a craniopharyngioma, which is a benign suprasellar tumor derived from the epithelial remnants of Rathke pouch, is the most common cause of acquired hypopituitarism and central diabetes insipidus. It compresses the pituitary stalk and functional tissue, leading to multiple hormone deficiencies.

Adım Adım Çözüm

1
Interpret the clinical symptoms and physical exam findings.
The patient exhibits growth failure, weight gain, fatigue, cold intolerance, bradycardia, and delayed reflex relaxation, which strongly suggest hypothyroidism. The severe polyuria, polydipsia, and nocturia suggest diabetes insipidus.
Identifying the clinical syndromes present is the first step in diagnosing complex endocrine disorders.
2
Analyze the laboratory results to determine the specific types of endocrine dysfunction.
A low free T4 with an inappropriately low TSH confirms central (secondary) hypothyroidism. Hypernatremia and elevated serum osmolality with a simultaneously low urine osmolality confirm central diabetes insipidus when considered with the hypopituitarism.
Laboratory confirmation distinguishes primary from secondary/central endocrine failure, which localizes the lesion.
3
Synthesize the findings to identify a single unifying diagnosis.
The combination of central hypothyroidism and central diabetes insipidus localizes the lesion to the hypothalamus or pituitary stalk. In a child, a craniopharyngioma (arising from Rathke pouch remnants) is the most common mass lesion causing panhypopituitarism.
A single etiology should explain all objective findings in a clinical vignette.

Anahtar Kavram

Craniopharyngioma presenting with panhypopituitarism
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Konular

Pediatric Endocrine Disorders

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