4 Electrolyte Imbalances Free Online FlashCards

What chiefly determines serum sodium concentration?

It reflects body water relative to exchangeable sodium and potassium, so dysnatremia often represents a water-balance disorder rather than a change in total sodium stores.

What does hypernatremia usually indicate, and how is chronic disease corrected?

Serum sodium above $145\ \mathrm{mEq/L}$ usually indicates a water deficit relative to sodium. Chronic or unknown-duration cases are generally corrected gradually to reduce cerebral-edema risk.

What neurologic danger can rapid or severe hyponatremia cause?

Water may move into brain cells, causing confusion, seizures, coma, or respiratory compromise.

How can insulin change serum potassium without changing total-body stores?

Insulin and beta-adrenergic stimulation shift potassium into cells. Thus, serum potassium can change without a matching change in total-body potassium.

What threshold and ECG changes characterize hypokalemia?

Hypokalemia is serum potassium below $3.5\ \mathrm{mEq/L}$. It may cause weakness and cramps; ECG changes can include flattened T waves and prominent U waves.

What is a critical safety rule for IV potassium?

Never give potassium by IV push. IV potassium must be diluted and infused at a controlled rate.

What does IV calcium do in emergency hyperkalemia?

IV calcium temporarily stabilizes cardiac membranes and reduces cardiac toxicity; it does not lower serum potassium.

Why can total calcium be misleading when albumin is low?

Ionized calcium is the biologically active form. Low albumin can lower total calcium without lowering ionized calcium, so total calcium may be misleading.

Why can magnesium deficiency make low calcium or potassium persist?

Magnesium deficiency can impair PTH release and action, making hypocalcemia persistent; it can also make hypokalemia difficult to correct.

Which laboratory hormone is a key initial discriminator in hypercalcemia?

PTH is a key initial discriminator when investigating hypercalcemia; primary hyperparathyroidism and malignancy are common causes.

What signs can indicate worsening hypermagnesemia toxicity?

Increasing toxicity can cause diminished deep-tendon reflexes, hypotension, bradycardia, respiratory depression, and eventually cardiac arrest.

How can refeeding or insulin treatment precipitate hypophosphatemia?

Refeeding after prolonged malnutrition and insulin treatment can shift phosphate into cells, precipitating hypophosphatemia.