For a patient with hyperglycemic hyperosmolar syndrome (HHS), should corrected sodium (Na+) or measured sodium be used for calculating osmolarity?

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Cálculo de Osmolaridad en el Estado Hiperglucémico Hiperosmolar

Para el cálculo de la osmolaridad efectiva en el síndrome hiperglucémico hiperosmolar (SHH), se debe utilizar el sodio MEDIDO, no el sodio corregido. 1, 2

Fórmula Estándar para Osmolaridad Efectiva

La fórmula establecida por las guías de la American Diabetes Association es clara y específica: 1

  • Osmolaridad sérica efectiva = 2[Na+ medido (mEq/L)] + glucosa (mg/dL)/18 1, 3
  • Esta fórmula utiliza explícitamente el sodio medido, no el corregido 1
  • El criterio diagnóstico de SHH requiere una osmolaridad efectiva >320 mOsm/kg H₂O calculada con esta fórmula 1, 3

Diferencia Crítica: Sodio Medido vs. Corregido

Es fundamental entender que el sodio medido y el sodio corregido tienen propósitos clínicos diferentes: 1, 4

Sodio Medido (para osmolaridad):

  • Se utiliza para calcular la osmolaridad sérica efectiva 1
  • Refleja el estado osmótico real del paciente 2
  • Guía el diagnóstico inicial de SHH (osmolaridad >320 mOsm/kg) 1, 3

Sodio Corregido (para decisiones de reposición de líquidos):

  • Se calcula agregando 1.6 mEq por cada 100 mg/dL de glucosa >100 mg/dL 1, 4
  • Se utiliza para determinar qué tipo de solución salina administrar (0.45% vs 0.9% NaCl) 1, 4
  • Refleja el verdadero déficit de agua libre del paciente 5, 6
  • No se usa para calcular osmolaridad 1

Evidencia Reciente y Consideraciones Adicionales

Un estudio de 2025 encontró que el 95.4% de los pacientes con SHH tienen hipernatremia cuando se usa el sodio corregido, pero solo el 8% cuando se usa el sodio medido. 5 Esto confirma que:

  • El sodio corregido es más sensible para identificar el verdadero déficit de agua libre 5, 6
  • La osmolaridad efectiva calculada con sodio medido sigue siendo el estándar diagnóstico 5
  • Ambos valores (medido y corregido) deben evaluarse, pero para propósitos diferentes 5, 6

Algoritmo Práctico

  1. Para diagnóstico de SHH: Calcular osmolaridad efectiva = 2[Na+ medido] + glucosa/18 1
  2. Para decisiones de líquidos: Calcular Na+ corregido = Na+ medido + 1.6 × [(glucosa - 100)/100] 1, 4
  3. Monitoreo: Seguir ambos valores durante el tratamiento 4, 5

Trampa Común a Evitar

No confundir las fórmulas: El error más frecuente es usar el sodio corregido en la fórmula de osmolaridad, lo cual sobrestimaría falsamente la osmolaridad y podría llevar a decisiones terapéuticas incorrectas. 1, 6 Las guías británicas (JBDS) también confirman que la osmolaridad se calcula como [(2×Na+) + glucosa + urea], usando explícitamente el sodio medido. 2

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

3
Guideline

Hyperosmolar Hyperglycaemic Syndrome Management

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

4
Guideline

Management of Hypernatremia in Hyperosmolar Hyperglycemic State (HHS)

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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