Hyponatremia Key Points

Homepage: EMNote.org ■ 🚩Membership: https://tinyurl.com/joinemnote 🚩ACLS Lecture: https://tinyurl.com/emnoteacls 10 Key Points Hyponatremia 1: What is Hyponatremia? Serum sodium level below 135 mmol/L Represents excess water relative to sodium in body Often involves elevated antidiuretic hormone (ADH) 2: Hyponatremia Severity Mild: 125-134 mmol/L Moderate: 120-124 mmol/L Severe: below120 mmol/L 3: Types of Hyponatremia Hypoosmolar: Most common (hypovolemic, euvolemic, hypervolemic) Iso-osmolar: "Pseudohyponatremia" due to elevated lipids/proteins Hypertonic: Caused by osmotically active particles like glucose 4: Causes of Hypovolemic Hyponatremia Results from loss of both water and sodium from ECF Renal causes: diuretic use, salt-wasting nephropathy Extra-renal causes: vomiting, diarrhea, sweating 5: Causes of Euvolemic Hyponatremia Main cause: Syndrome of Inappropriate ADH Secretion (SIADH) Other causes: psychogenic polydipsia, hypotonic IV fluids Also seen in adrenal insufficiency and hypothyroidism 6: Causes of Hypervolemic Hyponatremia Occurs when increase in total body water exceeds sodium Results in edema or ascites Common in heart failure, cirrhosis, and nephrotic syndrome 7: Recognizing Symptoms Mild cases often asymptomatic Symptoms appear below 125 mmol/L: nausea, headache, confusion Severe cases: seizures and coma possible 8: Diagnosing Hyponatremia Requires history, physical exam, and lab tests Blood tests: sodium, osmolality, glucose, urea, creatinine Urine sodium and osmolality help determine cause 9: Managing Hyponatremia Treatment based on cause, severity, and symptoms Options: fluid restriction, diuretics, isotonic saline Severe cases may need hypertonic saline 10: Risks of Rapid Correction Avoid rapid correction to prevent osmotic demyelination syndrome Aim for 4-6 mmol/L increase in first 24 hours for severe cases Maximum correction: 0.5 mmol/L/hr unless critically symptomatic