Hyponatremia

Homepage: EMNote.org ■ 🚩Membership: https://tinyurl.com/joinemnote 🚩ACLS Lecture: https://tinyurl.com/emnoteacls Hyponatremia Hyponatremia is defined as serum sodium below 135 mmol/L It represents excess water relative to sodium in the body Symptoms typically appear when sodium drops below 125 mmol/L Pathophysiology Hyponatremia occurs due to disruption in sodium and water balance Kidneys regulate sodium and water excretion under hormonal influence Excess water relative to sodium leads to decreased serum sodium concentration Causes of Hyponatremia Increased water intake (e.g., psychiatric conditions, endurance sports) Decreased water excretion (e.g., CHF, cirrhosis, renal failure) Excessive sodium loss (e.g., diuretics, vomiting, diarrhea) Hormonal imbalances (e.g., SIADH) Certain medications (e.g., thiazide diuretics) Clinical Presentation Mild Hyponatremia (Na above 125 mmol/L): Non-specific symptoms: fatigue, weakness, muscle cramps Severe Hyponatremia (Na below 120 mmol/L): CNS symptoms: confusion, agitation, delirium, seizures Rate of sodium decline influences symptom severity Diagnosis Thorough history and physical examination Laboratory investigations: Serum sodium, serum osmolality Urine sodium and osmolality Additional tests based on suspected etiology Stepwise approach: assess osmolality, volume status, and urine studies Management Consider severity of symptoms and volume status Address underlying cause Severe symptomatic hyponatremia: hypertonic saline (3%) Mild-moderate asymptomatic hyponatremia: fluid restriction SIADH: consider ADH inhibitors (e.g., demeclocycline, vaptans) Prognosis Depends on underlying cause, severity, and correction rate Mild, chronic hyponatremia generally has good prognosis Severe, acute hyponatremia can lead to significant complications Overly rapid correction of chronic hyponatremia is may cause osmotic demyelination syndrome (central pontine demyelinosis). Close monitoring during treatment is crucial Some patients may require long-term management