Electrolytes

Question 1

How is calcium binding to albumin affected by pH?

Answer 1

Increased pH leads to increased binding (hydrogen ions dissociate from albumin freeing up space for calcium to bind). Decreased pH causes hydrogen ions to bind to albumin which leads to an increase in ionized calcium (dissociated calcium)

Question 2

What are symptoms of hypercalcemia?

Answer 2

Impaired neuromuscular excitability (weakness, diminished reflexes, and decreased gastrointestinal motility), anorexia, constipation, easy fatiguability, nausea and polydypsia

Question 3

What are symptoms of hypokalemia?

Answer 3

Weakness, fatigue and muscle cramps. In severe hypokalemia patients can get flaccid paralysis, hyporeflexia, tetany, rhabdomyolysis, and arrhythmias

Question 4

What are metabolic consequences of hypercalcemia?

Answer 4

Hypophosphatemia, hypomagnesemia, metabolic alkalosis, and acute kidney injury

Question 5

What is milk-alkali syndrome (MAS)?

Answer 5

Due to excessive intake of calcium. Causes abdominal pain, constipation, dry mouth, confusion, headache, and polydipsia (inhibits the Na-K-2Cl cotransporter and impairs ADH activity leading polyuria).

Question 6

What medications can exacerbate milk-alkali syndrome?

Answer 6

Thiazide diuretics, ACE-I/ARBs, and NSAIDS

Question 7

How do magnesium levels affect potassium?

Answer 7

Intracellular mag is thought to inhibit potassium secretion by the kidneys so hypomagnesemia can lead to potassium loss and therefore hypokalemia

Question 8

What is the management of severe hypercalcemia (>14 mg/dL)?

Answer 8

Short-term: normal saline plus calcitonin.

Long-term: bisphosphonates

Question 9

What electrolyte disturbance can cause fatigue, constipation and depression?

Answer 9

Hypercalcemia

Question 10

How does alkalosis and acidosis affect serum calcium levels?

Answer 10

Increased pH promotes binding of calcium to albumin leading to a lower serum ionized calcium concentration.
Decreased pH has the opposite affect

Question 11

What causes hypovolemic hyponatremia?

Answer 11

Vomiting or taking lasix

Question 12

How does hypocalcemia affect the QT interval?

Answer 12

Prolonged QT

Question 13

How does hypercalcemia affect the QT interval?

Answer 13

Shortened QT

Question 14

How are Ca, K, and phos levels affected in tumor lysis syndrome?

Answer 14

HyperK and hyperPhos due to intracellular ions being liberated –> hypoCa due to phos binding Ca