bone + joint Flashcards
What are the roles of calcium in the body?
Nerve impulse transmission, muscle contraction, bone health, cardiovascular support.
Where is most calcium stored in the body?
In the bones (>98%).
Normal blood calcium level?
~10 mg/dL.
Recommended daily calcium intake (RDA)?
1000–1200 mg/day.
Where is calcium absorbed?
Small intestine.
What increases calcium absorption?
Parathyroid hormone (PTH), Vitamin D.
What decreases calcium absorption?
Glucocorticoids.
Where is calcium excreted?
Primarily by the kidneys.
What increases calcium excretion?
Calcitonin.
How is calcium homeostasis regulated?
By parathyroid hormone, vitamin D, and calcitonin.
Effects of PTH?
↑ bone resorption, ↑ kidney reabsorption, ↑ Vit D activation → ↑ GI absorption.
Effects of Calcitonin?
↓ bone resorption, ↑ kidney excretion.
Effects of Vitamin D?
↑ bone resorption, ↓ kidney excretion, ↑ GI absorption.
Hypercalcemia
Often asymptomatic; affects kidney, GI, CNS.
Causes of hypercalcemia
Cancer, hyperparathyroidism, Vit D toxicity, sarcoidosis, thiazide diuretics.
Treatment for hypercalcemia
IV saline + diuresis; furosemide; calcitonin; bisphosphonates; glucocorticoids; EDTA.
Hypocalcemia
Increases neuromuscular excitability → tetany, convulsions, pharyngeal spasm.
Causes of hypocalcemia
PTH/Vit D deficiency, renal failure, magnesium laxatives, osteoporosis drugs.
Treatment for hypocalcemia
IV calcium gluconate (acute), oral calcium citrate + Vit D (maintenance).
Rickets/Osteomalacia
Vitamin D deficiency.
Osteoporosis
Most common calcium metabolism disorder.
Paget’s Disease
Abnormal bone remodeling.
Hypoparathyroidism
Low PTH → low calcium.
Hyperparathyroidism
Primary or secondary → high calcium.
