Chapter 24: Plasma Calcium, hypercalcemia, and hypocalcemia Flashcards Preview

Pathophysiology > Chapter 24: Plasma Calcium, hypercalcemia, and hypocalcemia > Flashcards

Flashcards in Chapter 24: Plasma Calcium, hypercalcemia, and hypocalcemia Deck (10):
1

Plasma Calcium

- present in three forms (1. bound to plasma proteins such as albumin 2. bound to small organic ions such as citrate 3. unbound)

- only free ionized calcium is physiologically active

2

Total Serum Calcium

- measures all of the calcium (bound + unbound)

- Normal range in adults = 9 to 11 mg/dl or 4.5-5.5 mEq/L

- unless a calcium value specifies ionized calcium, it is total calcium

3

Ionized Calcium

- measures only the unbound ionized form of calcium

- the normal range in adults = 4 to 5 mg/dl

- clinically significant calcium imbalances are caused by alteration in the plasma concentration of unbound calcium

4

Hypocalcemia

- serum calcium concentration drops below the lower limit of normal

- fraction of unbound ionized calcium in the blood lowers by more calcium binding to plasma proteins or other organic ions

- the total serum calcium may be normal

- ionized hypocalcemia is present and may cause signs and symptoms

5

Etiology of Hypocalcemia

- Decreased calcium intake or absorption (poor diet, lack of vitamin D, excessive phytates or oxalates)

- decreased physiologic availability of calcium (excessive phosphate, hypoparathyroidism)

- increased calcium excretion (steatorrhea and pacreatitis)

6

Clinical Manifestations of Hypocalcemia

- Decreases the threshold potential causing hyperexcitability of neuromuscular cells resutling in:

- positive trousseau sign (patient's hand looks wide and rigid)

- Positive Chvostek sign (tap on facial nerve and face starts to spasm, not reliable on infants)

- Parasthesias

- muscle twitching and cramping

- hyperactive reflexes

- carpal spasm

- pedal spasm

- tetany

- laryngospasm

- seizures

- cardiac dysrhythmias

7

Treatment of Hypocalcemia

- give replacement IV or oraly

- vitamin D

8

Hypercalcemia

- occurs when the serum calcium concentration rises above the upper limit of normal

- indicates an elevation of the calcium concentration of extracellular fluid

9

Etiology of Hypercalcemia

- Increased calcium intake or absorption (milk alkali syndrome, vitamin D overdose)

- Shift of calcium from bone to extracellular fluid (hyperparathyroidism, immobilization, bone tumors)

- Decreased calcium excretion (thiazide diuretics)

10

Clinical manifestations of Hypercalcemia

- causes decreased neuromuscular excitability caused by the elevation of the threshold potential of ecitabel cells which causes

- muscle weakenss

- diminished reflexes

- cardiac dysrhythmias

- anorexia, nausea, emesis

- fatigue

- polyuria

- constipation

- Headache, confusion, lethargy, personality change

- Renal calculi

- Pathological fractures