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[Endocrinological analysis of chronic hypernatremia in two cases of hydranencephaly]
H Endo1, S Kobayashi, T Nakamigawa
1Department of Pediatrics, Jichi Medical School, Tochigi.
Insights
Two infants with hydranencephaly experienced chronic hypernatremia due to impaired thirst mechanisms and antidiuretic hormone (ADH) secretion. Hypothalamic dysplasia was identified as the underlying cause of these critical regulatory dysfunctions.
Area of Science:
- Pediatric Neurology
- Endocrinology
- Neuroscience
Background:
- Hydranencephaly is a severe congenital brain malformation.
- Chronic hypernatremia poses significant health risks in infants.
- Disruptions in thirst regulation and antidiuretic hormone (ADH) secretion can lead to severe dehydration and electrolyte imbalances.
Observation:
- Two infants presented with hydranencephaly and progressively increasing plasma sodium levels, reaching 150-160 mEq/L.
- These infants exhibited an absence of thirst despite severe hypernatremia.
- Water deprivation tests revealed inappropriately low urine osmolality and suppressed plasma ADH levels relative to high plasma osmolality.
Findings:
- The infants demonstrated impaired thirst sensation and deficient ADH secretion, indicating a disturbed osmoregulation system.
- Administration of vasopressin successfully concentrated urine, confirming the kidneys' responsiveness to ADH.
- Radiographic imaging revealed hypothalamic dysplasia, suggesting an anatomical basis for the observed neuroendocrine dysfunction.
Implications:
- This case study highlights a rare dual defect in thirst and ADH regulation secondary to hypothalamic malformation in infants with hydranencephaly.
- Understanding these hypothalamic-pituitary-adrenal axis disruptions is crucial for managing electrolyte balance and neurological outcomes in affected infants.
- Further research into hypothalamic development and its role in osmoregulation may reveal novel therapeutic targets.
Abstract:
We reported two infants with hydranencephaly and chronic hypernatremia. Their plasma sodium concentration gradually increased during the first week and remained between 150-160 mEq/L thereafter. They showed no signs of thirst. A water deprivation test demonstrated low urine osmolality and low plasma ADH concentration despite markedly elevated plasma osmolality in both cases. Urine was significantly concentrated when vasopressin was given. Thus, it was concluded that both thirst mechanism and ADH secretion were disturbed in these two cases. ADH producing cells, the thirst center and the osmoreceptor are all located in the hypothalamus. Radiographic measures showed dysplasia of the hypothalamus, providing the anatomical basis for their dysfunction.