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Hyponatremia due to Severe Primary Hypothyroidism in an Infant
Nickolas T Agathis1, Ingrid M Libman2, Michael L Moritz2
1Texas Children's Hospital, Baylor College of Medicine , Houston, TX , USA.
Insights
Severe primary hypothyroidism can cause hyponatremia (low sodium) in infants. Prompt diagnosis and thyroxine treatment are crucial to prevent developmental delays in affected infants.
Area of Science:
- Pediatric Endocrinology
- Neonatal Medicine
- Internal Medicine
Background:
- Hyponatremia is occasionally reported in elderly patients with hypothyroidism.
- Reports of hyponatremia in children due to hypothyroidism are rare.
- Severe primary hypothyroidism can lead to significant electrolyte imbalances.
Observation:
- A 4-month-old ex-preterm infant developed hospital-acquired hyponatremia (serum Na 124 mEq/L).
- The infant was euvolemic and asymptomatic, with no signs of myxedema.
- Newborn screening indicated the infant was initially euthyroid.
Findings:
- The hyponatremia was solely attributed to severe primary hypothyroidism (TSH levels >300 IU/mL).
- Treatment with thyroxine supplementation successfully corrected the hyponatremia.
- Other potential causes for hyponatremia were ruled out.
Implications:
- This case highlights that severe hypothyroidism is a potential cause of hyponatremia in infants.
- Early consideration of hypothyroidism in infants with unexplained hyponatremia is critical.
- Untreated congenital hypothyroidism can result in severe, irreversible developmental delays.
Abstract:
Hyponatremia has been reported in the elderly with hypothyroidism and myxedema, but this has not been a universal finding in clinical studies and there have been only a few reports in children. We report a case of an infant who developed hyponatremia due to severe primary hypothyroidism. A 4-month-old ex-preterm male, who had been euthyroid on the newborn screen, developed unexplained hospital-acquired hyponatremia (serum Na 124 mEq/L) while on full oral feeds. He was euvolemic, appeared well and was without myxedema. An evaluation of hyponatremia was negative with the exception of severe primary hypothyroidism (TSH 315.4 IU/mL, repeat 540 IU/mL). The hyponatremia resolved with thyroxine supplementation. This case demonstrates that severe hypothyroidism can result in hyponatremia in infants. It is critical to consider hypothyroidism in the evaluation of an infant with unexplained hyponatremia as untreated hypothyroidism can lead to profound developmental delays.
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