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PHARM343 FLUID AND
ELECTROLYTE IMBALANCE LATEST
COMPLETE EXAM STUDY GUIDE ALL
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Fluid and Electrolyte Balance The body maintains fluid and electrolyte balance through three main mechanisms: Thirst Mechanism, Antidiuretic Hormone (ADH), and Renal Regulation. Thirst Mechanism Controlled by the hypothalamus, which detects high osmolality and signals thirst to promote fluid intake. Antidiuretic Hormone (ADH) Released from the posterior pituitary when osmolality is high, telling the kidneys to reabsorb water into the bloodstream. Renal Regulation The kidneys filter the blood and selectively reabsorb water and electrolytes depending on what the body needs.
Rehydration Can be oral or intravenous (IV); oral rehydration is for mild to moderate dehydration, while IV rehydration is for severe dehydration. Oral Rehydration For clients who can swallow and have mild to moderate dehydration, using water, electrolyte solutions, or sports drinks. IV Rehydration Needed for severe dehydration or when the client cannot tolerate oral intake, using IV fluids like D5W or normal saline. Overhydration Administering fluids too quickly can lead to fluid overload, especially in older adults or clients with heart failure. Electrolyte Imbalances Giving too much hypotonic or hypertonic fluid can shift electrolytes dangerously.
Infection Risk Increased risk if blood products are not screened properly. Nurse's Role in Fluid Imbalance Monitor labs, assess signs and symptoms, administer fluids or electrolytes, educate clients, and document intake and output. Acid-Base Balance Regulated by buffer systems, respiratory system, and renal system to maintain pH between 7.35 and 7.45. Buffer Systems Bicarbonate (HCO3-) binds or releases hydrogen ions to adjust pH. Respiratory System Lungs remove CO2 (acid), and fast breathing removes more acid. Renal System Kidneys excrete or retain hydrogen ions and bicarbonate to balance pH.
Metabolic Acidosis Condition where the lungs compensate by breathing faster to remove CO2. Metabolic acidosis A condition where the body produces excess acid or when the kidneys are not removing enough acid from the body. Compensation by lungs Breathing faster to remove CO2 in response to metabolic acidosis. Kidneys' role in acidosis Excrete hydrogen and reabsorb bicarbonate to help correct acid-base balance. Symptoms of acid-base imbalance Confusion, deep or shallow breathing, fatigue, cardiac arrhythmias. ABG results
Functions of electrolytes Help move nutrients into cells, remove waste, keep the heart beating, help muscles work, and maintain brain and nerve function. Basic Metabolic Panel (BMP) A blood test that checks kidney function, blood bicarbonate level, blood sugar level, blood chloride level, blood potassium level, and blood sodium level. Comprehensive Metabolic Panel (CMP) A blood test that includes all BMP tests plus liver function tests. Water balance Key to ensuring electrolytes are not too diluted or too concentrated. Kidneys' function Filter out waste and regulate how much water and electrolytes stay in the body. Hypothalamus role Detects when blood is too concentrated and triggers thirst.
ADH (antidiuretic hormone) Released by the pituitary gland to tell kidneys to retain water. Water composition in babies ~70% water. Water composition in men ~60% water. Water composition in women ~54% water. Osmosis The movement of water from areas with high water concentration to areas with low water concentration. Water storage compartments Intracellular (inside cells), interstitial (space between cells), intravascular (in blood vessels).
Interstitial Holds 25% of water. Intravascular Holds 8% of water. Osmosis Water moves from areas with more water to areas with more solutes to balance fluids across membranes. Thirst mechanism Starts in the brain when the blood gets too concentrated. ADH (antidiuretic hormone) Helps kidneys hold onto water when you're dehydrated. Kidneys
Reabsorb needed water and electrolytes and remove waste. Normal Electrolyte Ranges (adults) Potassium (K+): 3.5-5 mEq/L, Sodium (Na+): 136-145 mEq/L, Calcium (Ca2+): 9-10. mg/dL, Magnesium (Mg2+): 1.3-2.1 mEq/L. Fluid loss causes Diarrhea, vomiting, sweating, or bleeding. Overhydration causes Drinking too much water or getting too much IV fluid. Potassium's Role Helps the muscles and nerves work — especially the heart's electrical rhythm. Hypokalemia Low Potassium < 3.5 mEq/L.
Hyponatremia Low Sodium < 136 mEq/L. Causes of Hyponatremia Drinking too much water, diuretics, heart failure, liver disease, kidney problems, vomiting, diarrhea, excess alcohol, SIADH. Symptoms of Hyponatremia Nausea, headache, lethargy, confusion, seizures, muscle cramps, severe: coma or death from brain swelling. Sodium 122 mEq/L Hypernatremia High Sodium > 145 mEq/L Causes of Hypernatremia
Water loss (fever, diarrhea, sweating, diabetes insipidus), not drinking enough water, tube feedings without water, medications like corticosteroids. Symptoms of Hypernatremia Thirst, dry mouth, confusion, restlessness, irritability, muscle twitching, severe: seizures, coma, death. Example of Hypernatremia An elderly patient with dementia forgets to drink water. They are found very confused, with sodium of 155. They are given IV D5W slowly to rehydrate without causing brain swelling. Hypocalcemia Low Calcium < 9 mg/dL or ionized < 4.5 mg/dL Causes of Hypocalcemia Low vitamin D intake, hypoparathyroidism, kidney disease, long-term use of diuretics or steroids, multiple blood transfusions, electrolyte imbalances. Symptoms of Hypocalcemia
Example of Hypercalcemia An older adult with lung cancer reports constipation, bone pain, and confusion. Their calcium level is 12.2 mg/dL. IV fluids and loop diuretics are started to lower calcium. Hypomagnesemia Low Magnesium < 1.3 mEq/L Causes of Hypomagnesemia Poor diet or malnutrition, alcoholism, GI disorders, diuretics, diabetes, prolonged vomiting or pancreatitis. Symptoms of Hypomagnesemia Muscle cramps or tremors, numbness/tingling, seizures, positive Chvostek and Trousseau signs, irregular heartbeat, personality changes or confusion. Example of Hypomagnesemia A client with chronic alcoholism has muscle spasms and an irregular heartbeat. Their magnesium level is 0.9 mEq/L.
Calcium's Role Calcium (Ca2+) helps with strong bones and teeth, muscle movement, nerve signals, blood clotting, and heart function. Normal Serum Calcium Range 9-10.5 mg/dL Ionized Calcium Range 4.5-5.6 mg/dL Magnesium's Role Magnesium (Mg2+) helps regulate nerve and muscle function, blood sugar, blood pressure, and protein synthesis. Normal Magnesium Range 1.3-2.1 mEq/L Magnesium Storage 50-60% of magnesium is stored in bones.
Nursing Role in Hypomagnesemia Monitor magnesium, potassium, and calcium levels (they're often low together), Administer magnesium supplements (oral or IV depending on severity), Monitor ECG for arrhythmias, Educate on magnesium-rich foods: spinach, nuts, beans, dark chocolate, Watch for signs of improvement (muscle relaxation, normal ECG). Hypermagnesemia High Magnesium > 2.1 mEq/L. Causes of Hypermagnesemia Kidney failure (most common), Overuse of magnesium-containing meds (antacids, laxatives), Hypothyroidism, Bowel disorders slowing absorption. Symptoms of Hypermagnesemia Nausea, flushing, dizziness, Muscle weakness, Decreased deep tendon reflexes, Slow breathing or respiratory depression, Severe: Low heart rate, cardiac arrest, coma. Hypermagnesemia Example
A patient with chronic kidney disease reports weakness and low energy. Magnesium level is 3.8 mEq/L. Treatment includes IV calcium gluconate to protect the heart and possibly dialysis. Nursing Role in Hypermagnesemia Monitor magnesium and kidney labs (BUN/Creatinine), Administer ordered meds: calcium gluconate, diuretics, Prepare for dialysis if needed, Teach to avoid magnesium-containing meds, Monitor breathing, reflexes, and heart rhythm. Fluid Imbalances Overview Fluid balance means the right amount of water inside and outside your cells. Fluid imbalances happen when there's too little or too much water in the body. Dehydration Loss of water without losing sodium. Causes higher sodium concentration in the blood (hypernatremia). Causes of Dehydration Not drinking enough water, Diarrhea or vomiting, Fever or sweating, Diabetes (especially diabetic ketoacidosis), Medications that increase urination.
