Fluids & Electrolytes

What factors influence fluid balance in the body?

Hydration or volume status, electrolyte concentration, medications, hormones, and medical conditions.

What is homeostasis?

Homeostasis is the normal functioning of the body maintained through feedback systems, acid–base balance, and electrolyte balance.

What are the main cellular transport mechanisms?

Osmosis, diffusion, simple diffusion, facilitated diffusion, and active transport.

What is hypovolemia?

Fluid volume deficit where there is not enough circulating fluid in the body.

What GI causes can lead to hypovolemia?

Vomiting, nasogastric suction, and diarrhea.

What dehydration-related factors cause hypovolemia?

Decreased intake, aging, illness, and use of diuretics.

What emergency conditions can cause hypovolemia?

Hemorrhage, burns, diabetes insipidus, diaphoresis, and diabetic ketoacidosis.

What cardiovascular signs occur with hypovolemia?

Tachycardia and hypotension.

What skin and mucous membrane findings occur with hypovolemia?

Dry skin, dry mucous membranes, poor skin turgor, and sunken eyeballs.

What other physical findings suggest hypovolemia?

Weight loss, cool clammy or flushed warm skin, neurological changes, and flattened neck veins.

What lab changes occur with hypovolemia?

Increased hemoglobin and hematocrit, increased serum and urine osmolality, increased urine specific gravity, decreased urine sodium, and increased BUN and creatinine.

How is hypovolemia treated?

Increase volume with oral fluids or IV fluids using a fluid volume challenge.

What is hypervolemia?

Fluid volume excess with too much circulating fluid.

What intake-related causes lead to hypervolemia?

Increased fluid intake, excess salt intake, and water intoxication.

What medications can cause hypervolemia?

Corticosteroids.

What diseases cause hypervolemia?

Congestive heart failure and syndrome of inappropriate ADH.

What vital sign changes occur with hypervolemia?

Hypertension, tachycardia, and tachypnea.

What physical signs are seen with hypervolemia?

Edema, ascites, jugular vein distention, skin pallor, cool skin, shortness of breath, and weight gain.

What lab findings occur with hypervolemia?

Decreased hemoglobin and hematocrit, decreased serum and urine osmolality, decreased urine sodium, and decreased urine specific gravity.

How is hypervolemia treated?

Diuretics, dialysis, limiting sodium, and fluid restrictions.

What is the normal range for sodium?

135 to 145 mEq/L.

What are the main functions of sodium?

Determines extracellular fluid volume and osmolality, maintains blood pressure and volume, and helps regulate pH.

What is hyponatremia?

Sodium level less than 135 mEq/L.

What intake problems cause hyponatremia?

Too much water intake or not enough salt intake.

What losses cause hyponatremia?

Vomiting, NG suction, diarrhea, diaphoresis, tap water enemas, malnutrition, and diuretics.

What disease states cause hyponatremia?

Heart failure, cirrhosis, edema, ascites, water intoxication, adrenal insufficiency, and hypotonic IV fluids.

What manifestations occur with hyponatremia?

Tachycardia, hypotension, abdominal cramping, nausea, vomiting, diarrhea, anorexia, flushed skin, and neurological changes including seizures.

How is hyponatremia treated?

Increase sodium with oral salt, IV NaCl slowly, hypertonic solution if critical, and water restriction.

What is the safety rule for correcting hyponatremia?

Do not increase sodium more than 12 mEq/L in 24 hours.

What is hypernatremia?

Sodium level greater than 145 mEq/L.

What causes hypernatremia?

Not enough water, too much sodium, heat stroke, burns, watery diarrhea, diabetes insipidus, kidney failure, Cushing’s, glucocorticoids, and hypertonic IV fluids.

What symptoms occur with hypernatremia?

Hypertension, abdominal cramping, nausea, thirst, dry mucous membranes, poor skin turgor, warm flushed skin, and red swollen tongue.

How is hypernatremia treated?

Isotonic or hypotonic IV solutions, dialysis, and limiting sodium.

What is the safety limit for lowering sodium in hypernatremia?

No faster than 0.5–1 mEq/L per hour.

What is the normal chloride level?

98 to 106 mEq/L.

What are the functions of chloride?

Balances water, maintains acid–base balance, controls osmotic pressure, and has an inverse relationship with bicarbonate.

What is hypochloremia?

Chloride level less than 98 mEq/L.

What causes hypochloremia?

Malabsorption, vomiting, diarrhea, diaphoresis, NG suction, Addison’s, DKA, cystic fibrosis, heart failure, bicarbonate meds, and refeeding after starvation.

What are manifestations of hypochloremia?

Muscle cramps, tetany, dysrhythmias, seizures, coma, lethargy, and slow shallow respirations.

How is hypochloremia treated?

IV 0.9% or 0.45% NaCl and discontinuing loop diuretics.

What is hyperchloremia?

Chloride level greater than 106 mEq/L.

What causes hyperchloremia?

Excess chloride from IV infusions and head trauma.

What are signs of hyperchloremia?

Metabolic acidosis, hypernatremia, tachypnea, lethargy, and fluid retention.

How is hyperchloremia treated?

Treat the underlying cause, restore acid–base balance, and give hypotonic IV fluids.

What is the normal potassium level?

3.5 to 5 mEq/L.

Where is most potassium located?

98% is inside the cell.

What is hypokalemia?

Potassium less than 3.5 mEq/L.

What causes hypokalemia?

Inadequate intake, vomiting, NG suction, diarrhea, diaphoresis, malnutrition, diuretics, wound drainage, laxatives, hyperaldosteronism, Cushing’s, alcoholism, acid–base imbalance, corticosteroids, and insulin.

What muscle symptoms occur with hypokalemia?

Muscle weakness and decreased GI motility causing constipation or paralytic ileus.

What cardiac changes occur with hypokalemia?

Flat or inverted T waves.

What other symptoms occur with hypokalemia?

Nausea, vomiting, diarrhea, anorexia, confusion, and alkalosis.

How is hypokalemia treated?

Potassium-rich foods, supplements, and IV KCl slowly.

What is the critical rule for potassium IV?

Never IV push potassium.

What is hyperkalemia?

Potassium greater than 5 mEq/L.

What causes hyperkalemia?

DKA, Addison’s, MI, dehydration, sepsis, trauma, burns, kidney disease, potassium supplements, K-sparing diuretics, and ACE inhibitors.

What muscle and GI signs occur with hyperkalemia?

Muscle weakness, increased GI motility, cramps, and diarrhea.

What cardiac changes occur with hyperkalemia?

Peaked T waves, wide QRS, ventricular tachycardia, and possible cardiac arrest.

What acid–base change accompanies hyperkalemia?

Acidosis with H ions moving into cells and K moving out.

How is hyperkalemia treated?

Restrict potassium, change diuretics, Kayexalate, IV calcium gluconate, and in critical cases insulin with D5 or dialysis.

What is the normal calcium level?

8.5 to 10.5 mg/dL.

What are functions of calcium?

Nerve transmission, muscle contraction and relaxation, and 99% stored in bones.

What is hypocalcemia?

Calcium less than 8.5 mg/dL.

What causes hypocalcemia?

Diarrhea, laxatives, vitamin D deficiency, hypoparathyroidism, alkalosis, pancreatitis, burns, thyroid or parathyroidectomy, alcohol abuse, kidney failure, hyperphosphatemia, rapid transfusion, and phosphate supplements.

What neuromuscular signs occur with hypocalcemia?

Twitching, spasms, tetany, Chvostek’s and Trousseau’s signs.

What cardiac and GI signs occur with hypocalcemia?

Dysrhythmias, weak pulse, increased GI motility, diarrhea, cramping, nausea, and vomiting.

What neuro symptoms occur with hypocalcemia?

Confusion and seizures, and osteoporosis long term.

How is hypocalcemia treated?

Oral calcium and vitamin D, decrease phosphorus, and IV calcium gluconate slowly.

What is hypercalcemia?

Calcium greater than 10.5 mg/dL.

What causes hypercalcemia?

Hyperparathyroidism, Paget’s disease, thiazide diuretics, long-term steroids, excess antacids, and low phosphorus.

What symptoms occur with hypercalcemia?

Muscle weakness, strong cardiac contractions, dysrhythmias, constipation, nausea, vomiting, anorexia, lethargy, and kidney stones.

How is hypercalcemia treated?

Restrict calcium, give 0.9% NS, phosphate, furosemide, and calcitonin.

What is the normal magnesium level?

1.8 to 3.0 mg/dL.

What are magnesium functions?

Neuromuscular function and muscle contractility.

What is hypomagnesemia?

Magnesium less than 1.8 mg/dL.

What causes hypomagnesemia?

Malabsorption, diarrhea, NG suction, laxatives, hyperparathyroidism, hyperaldosteronism, Cushing’s, DKA, alcoholism, and diuretics.

What symptoms occur with hypomagnesemia?

Muscle twitching, tetany, tremors, ECG changes, constipation, paralytic ileus, and insomnia.

How is hypomagnesemia treated?

Oral magnesium, IV magnesium slowly, or magnesium oil like Epsom salt.

What is hypermagnesemia?

Magnesium greater than 3 mg/dL.

What causes hypermagnesemia?

Kidney failure, laxatives, antacids, and IV magnesium.

What manifestations occur with hypermagnesemia?

Muscle paralysis, weak cardiac contractions, lethargy, and shallow respirations.

How is hypermagnesemia treated?

Restrict magnesium, give IV calcium, loop diuretics, and NaCl or LR.

What is the normal phosphorus level?

2.5 to 4.5 mg/dL.

What are phosphorus functions?

Muscle function, RBC function, and acid–base balance.

What is hypophosphatemia?

Phosphorus less than 2.5 mg/dL.

What causes hypophosphatemia?

Malabsorption, high calcium, diarrhea, hyperparathyroidism, alcohol withdrawal, DKA, vitamin D deficiency, antacids, diuretics, and refeeding syndrome.

What symptoms occur with hypophosphatemia?

Muscle weakness, dysrhythmias, constipation, nausea, vomiting, anorexia, lethargy, and personality changes.

How is hypophosphatemia treated?

Increase phosphorus foods, decrease calcium, IV phosphorus, and treat hyperparathyroidism.

What is hyperphosphatemia?

Phosphorus greater than 4.5 mg/dL.

What causes hyperphosphatemia?

Excess intake, low calcium, kidney disease, dialysis, hypoparathyroidism, and diuretics.

What manifestations occur with hyperphosphatemia?

Low calcium leading to tetany, numbness, tingling, weak cardiac contractions, dysrhythmias, irritability, confusion, diarrhea, nausea, vomiting, and cramping.

How is hyperphosphatemia treated?

Increase calcium intake, decrease phosphorus, phosphate binders, and IV calcium carbonate slowly.

What do isotonic IV fluids do?

Expand extracellular fluid volume.

What are examples of isotonic fluids?

0.9% NaCl, D5NS, Lactated Ringer’s, and D5W after metabolism.

What do hypotonic IV fluids provide?

Sodium, chloride, and free water.

What is an example of hypotonic fluid?

0.45% NaCl.

What do hypertonic IV fluids do?

Increase extracellular fluid volume by pulling fluid from cells.

What are examples of hypertonic fluids?

3% NaCl and 5% NaCl.

What is the safety rule for hypertonic saline?

Must be given slowly and only in ICU.

What are colloid solutions used for?

To expand intravascular volume.