Electrolytes: Sodium and Potassium Lecture

Study Tools and Resources for Electrolytes

• The Electrolyte Person:     * This is a visual tool consisting of two line drawings of a human body, provided underneath the PowerPoint material.     * It is designed for visual learners to help them map out where electrolytes affect the body.     * Students in previous semesters have been very creative with these drawings to help the information stick.     * The use of this tool is not mandatory but highly recommended as a helpful study aid.

• General Learning Tools:     * A variety of tools are provided because different learning styles work for different people.     * Consistent study is framed as a habit to be developed.

Examination Protocols and Normal Values

• Testing Procedures:     * Starting this semester, students are no longer required to memorize normal electrolyte values for exams.     * During the exam, a list of normal values will be provided as a test attachment.     * Accessing Values: On the exam computer, click the three dots to go to "Tools." This is found in the same location as the calculator. Clicking the other tab will display the attachment of normal values.     * This change was implemented to align with the NCLEX, which provides normal laboratory values to test-takers.

• Clinical vs. Academic Values:     * The values listed in the course PowerPoints are derived specifically from Pearson.     * Students may notice that ranges used at clinical sites, such as UPMC, may differ slightly from Pearson values.     * Exam Strategy: For the purposes of testing and the NCLEX, students should answer questions based specifically on the range provided within the test environment.     * While memorization of exact numbers isn't required for the grade, students should still have a general idea of the ranges provided on lecture papers.

Fundamental Electrolyte Terminology

• Prefixes:     * Hyper-: Indicates levels that are too high.     * Hypo-: Indicates levels that are too low.

• Root Terms:     * -natremia: Refers to Sodium ($Na^+$).     * -kalemia: Refers to Potassium ($K^+$). The term is derived from the periodic table symbol for potassium, which is $K$.     * -calcemia: Refers to Calcium ($Ca^{2+}$). This starts with a "C" for calcium.

• Mnemonic for Terminology Confusion:     * It is common for students to mix up potassium and calcium during high-anxiety testing situations.     * If the term contains a "K" (e.g., Kalemia), it refers to Potassium ($K$).     * If the term contains a "C" (e.g., Calcemia), it refers to Calcium ($C$).

Sodium ($Na^+$)

• Normal Range: $135 \times 145\,mEq/L$.

• Location: Sodium lives primarily in the Extracellular Fluid (ECF). This can be inferred because its serum value ($135 - 145$) is much higher than that of potassium ($3.5 - 5$).

• Primary System Affected: Neurological (Neuro).

• Excretion: Sodium is lost through urine, sweat, and feces (stool).

• Hypernatremia ($Na^+ > 145\,mEq/L$):     * Critical Level: Often cited as over $160\,mEq/L$, though clinical concern begins much earlier.     * Description: The blood contains too much salt relative to water.     * Management: The primary goal is dilution by providing fluids. Fluids must be administered at a moderate rate to prevent rapid shifts that the body cannot handle.     * Etiology (Causes):         * Impaired thirst mechanism (patient is not drinking enough).         * Profuse sweating or diarrhea (losing fluid but retaining salt).         * Inappropriate use of electrolyte supplements (e.g., Element, which contains very high levels of salt).         * Cushing’s Syndrome: Excess cortisol causes the body to retain sodium.         * Diabetes Insipidus (DI): A brain/glandular issue (often caused by tumors) leading to the loss of large amounts of dilute urine, causing the body to pour off fluid rapidly.     * Manifestations (Signs and Symptoms - "FRIED and SALTED"):         * Neurological: Restlessness, agitation, irritability, decreased energy, lethargy, altered level of consciousness (LOC), and confusion.         * Fluid-Specific: Increased fluid retention (body trying to hold water), low urinary output, and extreme thirst.         * Other: Seizures (though more common in hyponatremia, they can occur in hypernatremia).

• Hyponatremia ($Na^+ < 135\,mEq/L$):     * Critical Level: The book lists less than $115\,mEq/L$ or $120\,mEq/L$.     * Management:         * Encouraging salt intake (e.g., salt tablets).         * Fluid restriction: If the low sodium is caused by fluid volume excess (over-dilution), restricting water intake will concentrate the sodium and raise the level.     * Etiology (Causes):         * Use of diuretics (causing loss of fluid and sodium).         * Excessive GI suctioning.         * Repeated tap water enemas.         * Fluid overload/excess.     * Manifestations (Signs and Symptoms - "SALT LOSS"):         * Neurological: Stupor, coma, lethargy, confusion.         * Musculoskeletal: Muscle weakness, fatigue, limp muscles.         * Major Concern: Seizures are highly common in hyponatremia due to fluid shifts in the brain.     * Nursing Interventions for Severe Hyponatremia (e.g., $116\,mEq/L$):         * Implement Seizure Precautions immediately.         * Place pads on the side rails of the bed.         * Ensure suction is available at the bedside.         * Maintain the bed in a low position.         * Note: A nurse does not need a doctor's order to implement seizure precautions as a safety measure.

Potassium ($K^+$)

• Normal Range: $3.5 - 5.0\,mEq/L$ (some lab sheets may use up to $5.3\,mEq/L$).

• Location: Potassium is primarily found inside the cell (Intracellular Fluid - ICF).

• Primary System Affected: Cardiac (Heart). It also affects the muscles.

• Dietary Intake: Must be ingested daily through foods such as bananas, citrus fruits, avocados, kiwis, potatoes, tomatoes, and salt substitutes (which use potassium instead of sodium).

• Hyperkalemia ($K^+ > 5.0\,mEq/L$):     * Critical Level: Cited as $7.0\,mEq/L$ in texts, though regular clinical concern starts above $5.0\,mEq/L$ ($6.0\,mEq/L$ in dialysis patients).     * Management:         * Potassium-wasting diuretics: Used if the patient is in fluid excess.         * Sodium Polystyrene Sulfate (Kayexalate): Binds potassium in the bowel to be eliminated through stool.         * IV Insulin: Pushes potassium out of the blood (serum) and back into the cells. This lowers serum levels but does not eliminate potassium from the body.         * Dextrose/Glucose: Must be given with IV insulin to prevent hypoglycemia in patients who have normal blood sugar.         * Calcium Gluconate: Given to stabilize the heart and prevent cardiac arrest; it does not lower the potassium level itself.     * Etiology (Causes):         * Potassium-sparing diuretics.         * Renal (kidney) failure (kidneys cannot excrete potassium).         * Severe tissue trauma (e.g., severe burns or crush injuries): When cells are damaged, they release their large internal stores of potassium into the bloodstream.     * Manifestations (Signs and Symptoms):         * Cardiac (Priority): Arrhythmias/Dysrhythmias (the heart not beating in normal rhythm).         * ECG Changes: Peaked (tall) T waves and a widened QRS complex.         * Medical Emergency: Significant risk of Cardiac Arrest.         * Other: Nausea, vomiting, and paresthesia (pins and needles sensation).     * Nursing Intervention: Place the patient on a heart monitor immediately.

• Hypokalemia ($K^+ < 3.5\,mEq/L$):     * Critical Level: Less than $2.5\,mEq/L$.     * Management: Potassium replacement and often Magnesium replacement.         * The Mg Connection: Magnesium helps run the Sodium-Potassium pump. If Magnesium is low, potassium replacement will be ineffective until magnesium is also replaced.     * Etiology (Causes):         * Potassium-wasting diuretics.         * Long-term IV fluid administration (e.g., Normal Saline) without potassium supplementation.     * Manifestations (Signs and Symptoms):         * ECG Changes: Flat or inverted (pointing down) T waves; appearance of a U wave.         * Musculoskeletal: Muscle cramping (e.g., leg cramps).         * Medication Risk: Increased risk for Digoxin Toxicity. Low potassium levels change how Digoxin binds to receptors, leading to toxic levels (Digoxin has a very narrow therapeutic range).

Summary of Priority and Application

• Sodium Focus: Neurological symptoms (LOC changes, mentation, seizures).
• Potassium Focus: Cardiac symptoms (arrhythmias, heart stabilization).
• Nursing Process: Always look for the cause (etiology). Fixing the electrolyte without fixing the underlying problem is like "throwing a Band-Aid on a bullet hole."
• Upcoming Topics: Potassium is only one of three major electrolytes that directly affect the heart; others will be discussed in subsequent lessons.