Calcium Flashcards
1
Q
Calcium?
A
- One of body’s most abundant ions (major ECF cation)
- Primarily combined w/ phosphorus to form mineral salts of bone + teeth
- Normal value is:
-8.5 - 10 mg/dL (total Ca++)
-Serum value is usually total Ca++ - Exerts sedative effect on nerve cells
- Fxs to develop cardiac action potential + contraction of muscle
- Necessary for blood clotting process
- Less than 1% of Ca++ is located in ECF + ICF compartments (of which approx 40% is bound to albumin
- 99% located in bone
- Phosphorus + calcium have inverse relationship
2
Q
Regulation
-Parathyroid hormone
A
- Released from parathyroid gland
- Promotes transfer of Ca from bones to ECF
- Activates vitamin D
- Promotes kidney reabsorption
3
Q
Regulation
-Vit D
A
- Major source of calcium is by oral intake of foods rich in Ca++
- Vit D is required to promote absorption of calcium via the GI tract
- Need fxing GI tract
Sources of vit D come from food + produced via the skin with exposure to sunlight
4
Q
Regulation
-Calcitonin
A
- Hormone produced by thyroid gland
- Acts as antagonist to PTH
- Inhibits bone resorption
- Enhances excretion by kidneys
- Decreases Calcium levels
5
Q
Hypocalcemia?
A
- Due to reduction of total body Ca++ or due to % of Ca++ that is ionized (look at albumin levels; low albumin is most common cause)
- Increased Ca++ loss
- Altered intestinal absorption
- Altered regulation
- Increased phosphorus or decreased Mg levels
6
Q
Hypocalcemia
-Clinical manifestations
A
- Related to diminished function of neuromuscular, cardiac + renal systems
- Numbness, tingling of hands, muscle spasms
- +Truosseau, +Chvosteks sign, increased DTRs
- Muscle cramps, can progress to tetany
- Cardiac arrhythmias
Other electrolyte imbalances associated w/ hypocalcemia?
7
Q
Hypocalcemia
-Diagnostic tests
A
- Serum Ca++ less than 8.5
- Look at serum albumin less than 3.5
- Xray findings may show osteoporosis, bone cavitation
8
Q
Hypocalcemia
-Interventions
A
- Monitor for signs of hypocalcemia
- Administer po calcium + Vit D supplement as ordered
- May need phosphorus binding antacids
- Encourage foods rich in Ca++/low in PO-4
- Administer IV calcium as ordered (use caution)
- Seizure precautions
- Observe for bleeding or bruising
9
Q
Hypercalcemia?
A
- Typically develops when there is an increased movement of calcium from bone to ECF
- Shift of Ca++ from bone to ECF
- Increased intake & absorption
- Decreased Ca++ excretion
10
Q
Hypercalcemia
-Clinical manifestations
A
- Sx usually absent unless concentration is >11mg/dL
- Many effects related to excess Ca++ in cells, which causes a decrease in cell membrane excitability. Esp in skeletal & heart muscle and nervous system.
- Weakness, decreased or absent DTRs
- Bone pain
- Constipation
- Potential for renal calculi (flank pain, abdominal pain)
- Dysrhythmia
11
Q
Hypercalcemia
-Lab findings
A
- Total serum Ca++ > 10.5mg/dL (also look at albumin level)
- Ionized Ca++ > 5.3mEq/L
- PTH increased w/ hyperparathyroidism
- Xray findings show osteoporosis, bone cavitation
12
Q
Hypercalcemia
-Interventions
A
- Monitor for worsening hypercalcemia
- Monitor for altered sensorium
- Provide safe environment
- Monitor for signs of digoxin toxicity, if taking digoxin
- Administer saline & loop diuretics, as prescribed
- Avoid Vit D preparations
- Low Ca++ diet, avoid Ca++ containing meds
- Monitor renal fx
- Monitor for kidney stones
