FINAL EXAM bones and joint disorders

Essential for nervous system function, muscle contraction, and cardiovascular function

calcium

Regulated by the thyroid gland (calcitonin) and parathyroid glands (PTH)

calcium homeostasis

Bone cells stimulated by PTH that break down bone (bone resorption)

osteoclasts

Breakdown of bone by osteoclasts, releasing calcium into the blood.

bone resorption

Bone cells stimulated by calcitonin that build bone (bone deposition)

osteoblasts

Process of building bone using calcium from the blood

bone deposition

Promotes calcium absorption from the GI tract

vitamin D

Inactive vitamin D produced in skin from sunlight/cholesterol or obtained from diet.

cholecalfierol

Vitamin D form produced in the liver from cholecalciferol

calcifediol

Active vitamin D produced in kidneys from calcifediol

calcitriol

Calcitriol; promotes calcium absorption in the GI tract

active vitamin D

Increases serum calcium by stimulating bone resorption and activating vitamin D

PTH (parathyroid hormone)

normal serum calcium

8-10 mg/dL

Serum calcium less than 8 mg/dL.

hypocalcemia

Low dietary calcium, vomiting, malabsorption, CKD, low PTH, transfusions, anticonvulsants, and calcium-lowering drugs

causes of hypocalcemia

Symptoms of hypocalcemia

increased muscle and nerve excitability

Available as acetate, carbonate, chloride, gluconate, lactate, and phosphate

calcium supplement

Common side effects of calcium

nausea, vomiting, constipation, metallic taste

Serious adverse effects of calcium

Hypercalcemia, dysrhythmias, renal stones, confusion, coma

Vitamin D forms

calcitriol and ergocalciferol

Vitamin D toxicity

causes hypercalcemia

Bone disorder caused by abnormal mineral or hormone balance affecting calcium homeostasis

metabolic bone disease

Examples of metabolic bone disease

osteomalacia, paget’s disease, osteoporosis

Softening of adult bones caused by vitamin D and calcium deficiency

osteomalacia

Childhood form of osteomalacia

rickets

Treatment for osteomalacia

calcium and vitamin D supplementation

Chronic bone disorder causing abnormal bone breakdown and rebuilding, resulting in weak bones

paget’s disease

Other name for Paget’s disease

Osteitis deformans

Most common metabolic bone disease characterized by decreased bone density and increased fracture risk

osteoporosis

Main mechanism of osteoporosis

bone resorption exceeds bone deposition

Menopause, aging, family history, alcohol, smoking, Caucasian/Asian race, inactivity, hormone deficiency, low calcium/vitamin D, corticosteroids.

risk factors for osteoporosis

Diagnostic test used to measure bone mineral density (BMD)

DEXA scan

Dual-Energy X-ray Absorptiometry.

DEXA

Purpose of DEXA scan

diagnose osteoporosis and assess fracture risk

Compares patient bone density to healthy young adult bone density

t-score

normal t-score

above -1

Osteopenia T-score

between -1 and -2.5

Osteoporosis T-score

below -2.5

Bisphosphonates, hormone replacement therapy, calcitonin, denosumab, raloxifene, teriparatide

drug classes for osteoporosis

Osteoporosis supplementation

patients need calcium plus vitamin D

First-line osteoporosis drugs that inhibit bone resorption

biphosphonates

Alendronate (Fosamax), ibandronate (Boniva), risedronate (Actonel), zoledronic acid (Reclast/Zometa)

examples of biphosphonates

nausea, heartburn, diarrhea, bone pain, back pain

common side effects of biphosphonates

Atypical fractures, nephrotoxicity, hypocalcemia, GI ulceration, osteonecrosis of jaw, dysrhythmias

serious adverse effects of biphosphonates

Major teaching for bisphosphonates

must follow administration instructions exactly

Bisphosphonates also treat

paget’s disease

Osteoporosis drug that decreases bone resorption; commonly given as nasal spray

calcitonin (miacalcin)

Runny nose, facial flushing, hand flushing.

common side effects of calcitonin