Hyponatremia

• Hyponatremia: Na <135 mEq/L

  • Mild: 130-134 mEq/L

  • Moderate: 125-129 mEq/L

  • Severe: <125 mEq/L

  • Eunatremia/normonatremia: Na 135-145 mEq/L

• Chronicity:

  • Acute if <48 hours, "chronic" if ≥48 hours

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https://learn.openpediatrics.org/learn/course/internal/view/elearning/2953/hyponatremia

https://learn.openpediatrics.org/learn/course/internal/view/elearning/3099/hyponatremia-in-the-critically-ill-child

Hypoosmolar hypotonic hyponatremia: https://i2.wp.com/nephsim.com/wp-content/uploads/2019/07/HypoNa-Graphic_2.png

Hyponatremia, osmolality and tonicity: https://i2.wp.com/nephsim.com/wp-content/uploads/2019/02/HypoNa-NephSim-2.png

Dabrafenib (BRAF inhibitor) and Trametinib (MEK inhibitor). Trametinib can be associated with hyponatremia. The mechanism is increased trafficking of aquaporin-2 channels to the apical membrane of the renal tubule, resulting in water retention and hyponatremia. In one case report (see below), hyponatremia resolved after trametinib was discontinued and recurred after restarting at a lower dose. Patients that were on both dabrafenib and trametinib had a higher incidence of hyponatremia compared to patients on only dabrafenib. BRAF inhibitors can also cause other renal-toxicities including acute interstitial nephritis, proximal tubular damage, electrolyte abnormalities (hyponatremia, hypokalemia, hypomagnesemia, hypocalcemia, and  Hypophosphatemia), and glomerular toxicity.