Podcast Beta
Questions and Answers
What is the primary role of 1,25(OH)2D3 in maintaining calcium levels?
What is the effect of estrogen deficiency on bone remodeling?
What is the effect of calcium and vitamin D supplements on bone mineral density?
What is the primary function of parathyroid hormone in relation to calcium levels?
Signup and view all the answers
What is the effect of hormone replacement therapy (HRT) on bone mineral density in postmenopausal women?
Signup and view all the answers
What is the role of vitamin D in bone health?
Signup and view all the answers
What is the effect of selective estrogen receptor modulators (SERMs) on bone health?
Signup and view all the answers
What is the importance of peak bone mass in children and adolescents?
Signup and view all the answers
What is the primary function of Parathyroid Hormone (PTH) in calcium homeostasis?
Signup and view all the answers
What is the effect of Calcitonin on calcium levels in the plasma?
Signup and view all the answers
What is the primary function of osteoclasts in bone turnover?
Signup and view all the answers
What is the primary mechanism by which weight resistance training helps to prevent bone deterioration in astronauts?
Signup and view all the answers
What is the normal range of calcium levels in the plasma?
Signup and view all the answers
What is the main goal of antiresorptive therapy in the treatment of osteoporosis?
Signup and view all the answers
Which of the following is an anabolic therapy for osteoporosis?
Signup and view all the answers
What is the role of Vitamin D in bone health?
Signup and view all the answers
What is the primary source of calcium in the body?
Signup and view all the answers
What is the mechanism by which PTH regulates bone turnover?
Signup and view all the answers
What is the purpose of bone remodeling in the body?
Signup and view all the answers
What is the role of vitamin D in bone health?
Signup and view all the answers
What is the consequence of excessive bone resorption?
Signup and view all the answers
What is the effect of insufficient dietary intake, intestinal absorption, or kidney reabsorption of calcium on the body?
Signup and view all the answers
What occurs when the rate of bone deposition is no longer able to match the rate of bone resorption?
Signup and view all the answers
Which type of therapy targets osteoblasts to increase bone deposition?
Signup and view all the answers
What is the primary mechanism of action of denosumab in osteoporosis treatment?
Signup and view all the answers
What is the result of osteoid mineralization?
Signup and view all the answers
What is the goal of therapeutic approaches to treat osteoporosis?
Signup and view all the answers
What is the role of osteoblasts in the bone remodeling process?
Signup and view all the answers
What is a consequence of osteoporosis?
Signup and view all the answers
What is the effect of intermittent treatment with teriparatide (PTH 1-34) on osteoporotic patients?
Signup and view all the answers
What is the mechanism of action of denosumab in the treatment of osteoporosis?
Signup and view all the answers
What is the primary difference between etidronate and other bisphosphonates such as alendronate and risedronate?
Signup and view all the answers
What is the role of RANKL in the regulation of osteoclast activity?
Signup and view all the answers
What is the primary mechanism of action of bisphosphonates in the treatment of osteoporosis?
Signup and view all the answers
What is the primary role of osteoblasts in the regulation of osteoclast activity?
Signup and view all the answers
What is the therapeutic limitation of denosumab in the treatment of osteoporosis?
Signup and view all the answers
What is the primary function of parathyroid hormone in relation to calcium levels?
Signup and view all the answers
What is the consequence of estrogen deficiency on bone remodeling?
Signup and view all the answers
Which of the following is a benefit of hormone replacement therapy (HRT) in postmenopausal women?
Signup and view all the answers
What is the primary mechanism of action of selective estrogen receptor modulators (SERMs) on bone health?
Signup and view all the answers
What is the primary goal of antiresorptive therapy in the treatment of osteoporosis?
Signup and view all the answers
What is the effect of vitamin D on calcium levels in the body?
Signup and view all the answers
What is the significance of peak bone mass in children and adolescents?
Signup and view all the answers
What is the primary regulator of calcium levels in the plasma?
Signup and view all the answers
Which cells do not have receptors for Parathyroid hormone (PTH)?
Signup and view all the answers
What is the purpose of bone remodeling in the body?
Signup and view all the answers
What would be the consequence of insufficient dietary intake, intestinal absorption, or kidney reabsorption of calcium?
Signup and view all the answers
What is the main goal of antiresorptive therapy in the treatment of osteoporosis?
Signup and view all the answers
What is the role of osteoblasts in bone remodeling?
Signup and view all the answers
Which of the following is NOT a regulator of calcium levels?
Signup and view all the answers
What is the result of severe bone deterioration?
Signup and view all the answers
Study Notes
Osteoporosis: Preventative Methods
- Calcium and vitamin D supplements are recommended to ensure sufficient dietary calcium in adults.
- Adequate levels of calcium and vitamin D maintain calcium levels, rather than increasing bone mineral density.
- Calcium and vitamin D may slightly reduce the risk of vertebral fractures in postmenopausal women.
- In children, peak bone mass is not achieved until 20-22 years, making calcium and vitamin D essential for maximal bone mass.
Vitamin D Metabolism
- Vitamin D has multiple forms in the body, with 1,25 Dihydroxy D3 (calcitriol) being the most biologically active form.
- Vitamin D can be obtained through dietary sources or sunlight conversion, followed by hydroxylation in the liver and kidney.
- Calcitriol reduces calcium excretion in the kidney and has maximum activity as a nuclear hormone receptor agonist.
- Calcitriol increases serum calcium by increasing absorption, decreasing elimination, and releasing calcium from bone.
Osteoporosis: Therapy
- Hormone Replacement Therapy (HRT) improves Bone Mineral Density (BMD) in postmenopausal women.
- HRT is associated with costs (increased incidence of uterine cancer, breast cancer, and venous thromboembolisms) and benefits (increased BMD and improved menopause symptoms).
Antiresorptive Therapy: HRT
- Estrogen deficiency results in increased bone remodeling, favoring resorption through increased osteoclast activity.
- Estrogen deficiency increases cytokine levels (IL-1, IL-6, and TNF), which favor osteoclast formation.
- HRT (estrogen) increases BMD in a dose-dependent manner.
Antiresorptive Therapy: SERMS
- Selective Estrogen Receptor Modulators (SERMs) are concerned with bone loading and weight resistance training.
- SERMs are important for astronauts to prevent severe bone deterioration.
Calcium Homeostasis
- Circulating calcium levels are between 2.15 and 2.55 mM or 8.7 to 10.3 mg/dL.
- Calcium levels are controlled by parathyroid hormone (PTH), vitamin D, and calcitonin.
- Calcium levels are affected by dietary intake, GI absorption, and renal clearance.
Key Regulator: PTH
- PTH increases circulating calcium levels by signaling osteoblasts to stimulate osteoclast activity.
- PTH is essential for maintaining calcium homeostasis and bone remodeling.
Overview: Bone Turnover
- Bone turnover involves growth and resorption throughout life, accommodating mechanical stresses and calcium homeostasis.
- The process of bone remodeling is under the control of local growth factors and endocrine factors, including PTH.
Bone Turnover
- Osteoid is a collagen-rich matrix that becomes mineralized and returns to normal
- Osteoblasts on the surface of bone produce osteoid, which then gets mineralized
- Osteoclasts on the surface of bone resorb old bone, leading to a net loss of bone
Osteoporosis
- Osteoporosis occurs when the rate of bone deposition is no longer able to match the rate of bone resorption, leading to a net loss of bone and decreased bone mineral density (BMD) and bone strength
- Therapeutic approaches to treat osteoporosis aim to either decrease bone resorption (anti-resorptive therapies) or increase bone deposition (anabolic therapies)
Osteoporosis Treatment
- Anti-resorptive therapies target osteoclasts to decrease bone resorption
- Anabolic therapies target osteoblasts to increase bone deposition
- Examples of anti-resorptive therapies include hormone replacement therapy (HRT), selective estrogen receptor modulators (SERMs), bisphosphonates, and denosumab
- Examples of anabolic therapies include parathyroid hormone (PTH) and sclerostin antibodies
Prevention Methods
- In adults, calcium and vitamin D supplements are recommended to ensure sufficient dietary calcium and vitamin D levels
- Calcium and vitamin D supplements do little to increase bone mineral density but ensure adequate levels of calcium and prevent the release of parathyroid hormone (PTH)
- Calcium and vitamin D supplements may slightly reduce the risk of vertebral fractures in postmenopausal women
- In children, peak bone mass is not achieved until 20-22 years, and calcium and vitamin D are essential for maximal bone mass
Vitamin D Metabolism
- Vitamin D has multiple forms in the body, with the most biologically active form being 1,25-dihydroxy D3 (calcitriol)
- Vitamin D can be obtained through dietary sources or conversion of precursors by sunlight, followed by hydroxylation in the liver and kidney
- Calcitriol has maximum activity in increasing serum calcium levels by increasing absorption, decreasing elimination, and increasing release from bone
- Calcitriol has high-affinity receptors in the intestine and kidneys
Antiresorptive Therapy: HRT
- Hormone replacement therapy (HRT) improves bone mineral density (BMD) all over the body in postmenopausal women
- HRT is associated with costs and benefits, including increased incidence of uterine cancer and breast cancer, and increased risk of cardiovascular events
- Estrogen deficiency results in increased bone remodeling, favoring resorption, mostly through increased osteoclast activity
- HRT (estrogen) increases BMD in a dose-dependent manner
Antiresorptive Therapy: SERMs
- Selective estrogen receptor modulators (SERMs) are examples of anti-resorptive therapies
- Examples of SERMs include etidronate and nitrogen-containing analogues, such as alendronate and risedronate
Antiresorptive Therapy: Bisphosphonates
- Bisphosphonates are examples of anti-resorptive therapies
- Examples of bisphosphonates include etidronate, alendronate, and risedronate
- Etidronate is a first-generation bisphosphonate, less potent than subsequent generations, and well-tolerated
- Alendronate and risedronate are administered continuously, well-tolerated, and reduce the risk of vertebral fractures and fractures of the spine, hip, and wrist
Antiresorptive Therapy: Denosumab
- Denosumab is a human monoclonal antibody to RANKL, which inhibits osteoclast differentiation and reduces bone resorption
- RANK is expressed on the surface of osteoclast precursors, and RANKL is expressed on the surface of osteoblasts
- Denosumab reduces osteoclast differentiation and activity by inhibiting the interaction between RANK and RANKL
Anabolic Therapies: PTH
- Parathyroid hormone (PTH) is secreted from the parathyroid glands in response to low serum calcium levels
- PTH acts in the kidney to stimulate calcium reabsorption and in bone to stimulate bone resorption, releasing stored calcium
- Intermittent treatment with teriparatide (PTH 1-34) stimulates bone turnover and reduces the risk of fractures in osteoporotic patients
Novel Anabolic Therapy: Sclerostin Antibodies
- Sclerostin antibodies are novel anabolic therapies that stimulate bone deposition
- Sclerostin antibodies work by inhibiting the sclerostin protein, which regulates bone formation and resorption
Calcium Homeostasis
- Circulating calcium levels in the plasma are between 2.15 and 2.55 mM or 8.7 to 10.3 mg/dL
- Calcium levels are controlled by parathyroid hormone (PTH), vitamin D, and calcitonin
- Calcium levels are affected by dietary intake, GI absorption, renal clearance, and bone absorption and release
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Learn about the preventative methods for osteoporosis in adults, including calcium and vitamin D supplements, and their roles in maintaining calcium levels and reducing the risk of vertebral fractures.
