Step 1: Determine the duration of hyponatremia
Is this acute (<48 h) or chronic (>48 h)? The duration determines how fast you should correct the sodium. You rapidly correct acute and slowly correct chronic hyponatremia.
Step 2: Determine the severity (degree) of hyponatremia
Mild hyponatremia = Na conc 130 to 134 mEq/L; Moderate hyponatremia =120 to 129 mEq/L; and Severe hyponatremia= Na conc <120 mEq/L
Step 3: Determine the severity of symptoms
Is the patient symptomatic or asymptomatic? Is patient malnourished, an alcoholic, has cirrhosis, older females on thiazides, hypoxia, hypokalemia? Any of these increases the risk of neurologic complications.
Step 4: Determine the need for hospitalization
With the above info, decide whether to tx inpatient or outpatient.
Step 5: Measure Plasma Osmolality to classify the hyponatremia as hypotonic, isotonic, and hypertonic.
Hypotonic hyponatremia is the true hyponatremia to to treat. It is also the most common scenario.
-Isotonic hyponatremia (pseudohyponatremia) is due to a rare lab artifact from hyperlipidemia or hyperproteinemia.
-Hypertonic hyponatremia is 2/2 to an excess of another osmole, e.g. glucose, mannitol, sorbitol, recent administration of radiocontrast media) that draws water intravascularly. For each 100 mg/dl increase in glucose >100, there will be a decrease in [Na+] of about 2.4mEq. That’s why in DKA for example, you have to correct the sodium.
Step 6: Check Volume Status (for patients with hypotonic hyponatremia)
Hypotonic hyponatremia is divided into three types based on volume status: Hypovolemic, euvolemic, and hypervolemic.
-Check mucous membranes, skin turgor, JVD, peripheral edema, vital signs, orthostatic vitals, BUN and uric acid levels.
