Week 11: Calcium Flashcards
What is important for regulating Calcium, Mg and Phosphate?
Parathyroid hormone
vitamin D
calcitonin
Normal Ca serum values:
8.8-10.5 mg/dL
What acts together to control Calcium absorption and excretion?
parathyroid hormone, vitamin D3, and calcitonin act together to control calcium absorption and excretion
What is the function of calcium?
- maintain structure of bones and teeth
- enzymatic cofactor for blood clotting
- needed for hormone secretion and function of cell receptors
- related to plasma membrane stability and permeability
- transmission of nerve impulses, and contraction of muscles
Hypercalcemia
serum concentrations greater than 10-12
Causes of hypercalcemia:
Hyperparathyroidism;
bone metastases with calcium resorption from breast, prostate, renal, and cervical cancer;
sarcoidosis;
excess vitamin D;
many tumors that produce PTH
Effects of hypercalcemia
fatigue,
weakness,
lethargy,
anorexia,
nausea,
constipation;
impaired renal function,
kidney stones;
dysrhythmias,
bradycardia,
cardiac arrest;
bone pain,
osteoporosis
Hypocalcemia
(serum calcium concentration <8.5 mg/dL)
Causes of Hypocalcemia
Related to inadequate intestinal absorption,
deposition of ionized calcium into bone or soft tissue,
blood administration, or
decreases in PTH and vitamin D; nutritional deficiencies occur with inadequate sources of dairy products or green leafy vegetables
Effects of hypocalcemia:
neuromuscular excitability;
tingling,
muscle spasm (particularly in hands, feet, and facial muscles),
intestinal cramping,
hyperactive bowel sounds;
severe cases show convulsions and tetany;
prolonged QT interval,
cardiac arrest
Mg normal serum values
Serum: 1.8-3.0
What does Mg do with enzymatic reactions?
Cofactor in intracellular enzymatic reactions
Mg function
Cofactor in intracellular enzymatic reactions and
causes neuromuscular excitability; often interacts with calcium and potassium in reactions at cellular level and has important role in smooth muscle contraction and relaxation;
What does Mg interact with at cellular level?
often interacts with calcium and potassium in reactions at cellular level
Functions of Mg:
causes neuromuscular excitability;
important role in smooth muscle contraction and relaxation;
Where is Mg absorbed and eliminated
magnesium is absorbed in the intestine and eliminated by the kidney
Hypermagnesemia
(serum concentrations >3.0 mEq/L)
Causes of hypermagnesemia
renal insufficiency or failure;
excessive intake of magnesium-containing antacids, adrenal insufficiency
Effects of hypermagnesemia
Skeletal smooth muscle contraction;
excess nerve function;
loss of deep tendon reflexes;
nausea and vomiting;
muscle weakness;
hypotension;
bradycardia;
respiratory distress
Hypomagnesemia
(serum magnesium concentration <1.5 mEq/L)
Causes of hypomagnesemia
Malnutrition,
malabsorption syndromes,
alcoholism,
urinary losses (renal tubular dysfunction, loop diuretics)
Effects of Hypomagnesemia
Behavioral changes,
irritability,
increased reflexes,
muscle cramps,
ataxia,
nystagmus,
tetany,
convulsions,
tachycardia,
hypotension
Treatment for hypomagnesemia
IV administration of Mag. sulfate
Treatment for hypermagnesemia
Calcium gluconate
