PATHO CH.7 PT.2

video lecture (electrolyte imbalances)

sodium

major extracellular cation. normal serum level is 135-145 mEq/L. maintains ECF volume via osmotic pressure, influences generation and conduction of nerve impulses, and is excreted or retained by kidneys along with water. if monitoring levels, it is important to examine the level of this cation along with an individuals hydration status.

potassium

major intracellular cation. normal serum level is 3.5-5.2 mEq/L. works in conduction of nerve impulses to muscles for contraction. serum level is regulated by kidneys (aldosterone causes secretion of this cation). abnormalities in this cation can lead to decreased neuromuscular excitability, or increased neuromuscular excitability, which can really affect the heart muscle. if monitoring levels, we must consider the serum level in light of acid-base balance.

hyponatremia

less than 135 mEq/L. can be caused by hypovolemia (loss of water and sodium via renal problems, vomiting, diarrhea, excessive sweating, diuretics, etc) or via hypervolemia (dilution of sodium due to high volume of water). can be clinically significant in brain and neurons, as it can lead to seizures or coma due to swelling into brain. blood osmolality is lowered along with osmotic pressure, hydrostatic pressure is increased, causing edema or swelling of the cells was water is unable to be pulled from cells.

hypernatremia

greater than 145 mEq/L. marked by the presence of high sodium in the blood (ECF), which causes an increase in oncotic pressure and a pull of fluids from the cell into the blood. this causes cellular dehydration and cellular shrinkage. central nervous system is especially sensitive to this issue and can severely impact a plethora of things throughout the body. most commonly caused through rapid water loss, but can also be caused by ingested excess salt or renal dysfunction.

hypernatremia symptoms

thirst, agitation, irritability, restlessness, issues with conduction of nerve impulses, and decreased urine output. if high sodium level leads to fluid retention, we could see edema, weight gain, and hypertension. if high sodium is caused by lack of fluid retention, we could see tenting and weight loss.

hypokalemia

less than 3.5 mEq/L. most commonly caused by diuretics and kidneys (potassium wasting), but can also be caused by alkalosis (keeps potassium in cell), inadequate intake (common in NPO patients, bariatric surgery, alcoholism, and/or eating disorders), and illness with fluid loss (vomiting, diarrhea). causes decreased neuromuscular excitability (huge for muscular and cardiac system), can lead to cardiac dysrhythmias, muscle fatigue, weakness, and cramps. can also show anorexia, nausea, vomiting, or sluggish bowels. also increases risk for digitalis toxicity.

hyperkalemia

greater than 5.2 mEq/L. most commonly caused by damaged kidneys, but can also be caused be cell membrane damages (due to ischemia, necrosis, and other body injuries), and acidosis. can cause dysrhymias and EKG changes (peaked T waves and widened QRS complexes), numbness/tingling, cramping, diarrhea, apathy, and/or mental confusion.

calcium

absorbed in GI tract with help of vitamin D. normal serum level is 8.7-10 mg/dL. once in the blood, levels are controlled by PTH. responsible for building and maintaining bones and teeth, helping in blood clotting, and regulating neuromuscular irritability.

hypocalcemia

less than 8.7 mg/dL. can be caused by a lack of sufficient dietary intake, vitamin D deficiency, low PTH, decreased serum albumin, renal disease, and hypoparathyroidism (dysfunction of parathyroid gland). causes an increased nerve excitability in skeletal muscle (numbness/tingling, seizures, and severe tetany), and a decreased muscle irritability in cardiac muscle (weaker contractions cardiac dysrhythmias from delays in conduction).

hypercalcemia

level greater than 10 mg/dL. can be caused by an increase in PTH, cancers (neoplasms) of the bone, or consuming too much calcium. causes a decreased nerve excitability in skeletal muscle (muscle weakness, decreased neuromuscular activity of the bowel) and increased muscle irritability in cardiac muscle (cardiac dysrhythmias—stronger contractions, faster HR).