importance of calcium: ca ++ regulates: neural function muscle contraction
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Importance of calcium:
Ca++ regulates:•Neural function•Muscle contraction•Secretion of some hormones•Blood clotting
The four parathyroid glands are located adjacent to the much larger thyroid gland.
Secretion of parathormone (PTH)is a direct responseto an abnormal decrease in the concentration of calcium ions.
RICKETS
• Insufficient Vitamin D3• Bones fail to mineralize due to lack of calcium• Bones are soft and easily fractured• Bones become distorted due to weight bearing• A major health problem in the US in the 1930’s• Vit D fortification of milk was introduced and largelyeliminated the problem• Still a major health problem in many developing nations• Has recently re-emerged in the US particularly amongAfrican American infants and children
Vitamin D
• Ca++ and PO4-- regulation • Blood pressure regulation
• Immunomodulatory effects
• Anti-cancer effects
• Anti-thrombotic effects
Most cells and tissues of the body have Vitamin D receptors
Vitamin D deficiency
Definition: serum 25-hydroxyvitamin D < 30 ng/ml
Epidemiology: 1 billion people worldwide have vitamin Ddeficiency or insufficiency
Risk factor for: • osteopenia• muscle weakness• increased risk of some cancers• autoimmune disease• hypertension• cardiovascular disease• asthma
Source: Vitamin D deficiency, Holick, MF, New Engl. J. Med. 357:266-280, 2007
Vitamin D deficiency
Risk factors:
Reduced skin synthesis: sunscreen, skin pigment, aging, season, latitude
Decreased bioavailability: malabsorption (GI problems), obesity(sequestration in fat)
Drugs that increase catabolism
Breastfeeding
Decreased synthesis: (liver or kidney failure)
Heritable Disorders
Source: Vitamin D deficiency, Holick, MF, New Engl. J. Med. 357:266-280, 2007
5 to 10 minutes of exposure (depending on the time of day, season, latitude, and skin sensitivity) of the arms and legs to direct sunlight.
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Hypercalcemia
• Serum calcium > 10.5 mg/100ml• High serum calcium makes nerves and muscle hypoexcitable
Signs and symptoms• Kidney stones• Bone pain and fractures• Anorexia• Constipation• Fatigue, weakness, and joint pain• Depression, memory loss, confusion, lethargy
Primary cause: Hyperparathyroidism,excess PTH release usually froma parathyroid adenoma
Hypocalcemia
• Serum calcium > 9 mg/100ml• low serum calcium makes nerves and muscle hyperexcitable
Signs and symptoms• Numbness and tingling• Muscle cramps and pain• Irritability• Impaired mutation• Seizures• Cardiac problems• Laryngospasm• Bronchospasm• Tetany
Primary cause: PTH or Vitamin D deficiency
OSTEOPOROSIS
OSTEOPOROSIS
• Loss of bone matrix and mineralization
SYMPTOMS OF OSTEOPOROSIS
• Often asymptomatic• Bone fractures (vertebrae, hip, wrists)• Bone pain• Back pain, neck pain• Loss of height• Stooped posture
From: Kettyle and Arky, Endocrine Pathophysiology, Lippincott -Raven
From: Kettyle and Arky, Endocrine Pathophysiology, Lippincott -Raven
From: Kettyle and Arky, Endocrine Pathophysiology, Lippincott -Raven
RISK FACTORS FOR OSTEOPOROSIS
• Age (affects ¼ of women over 50)• Race (highest in Caucasians)• Gender (more common in females)• Loss of growth promoting hormones (menopause)• Immobilization/lack of exercise• Genetics• Diet (calcium and vitamin D3)• Smoking and alcohol• Excess of hormones that cause bone resorption• Thyroid hormone• Corticosteroids
From: Kettyle and Arky, Endocrine Pathophysiology, Lippincott -Raven
RISK FACTORS FOR OSTEOPOROSIS
• Age (affects ¼ of women over 50)• Race (highest in Caucasians)• Gender (more common in females)• Loss of growth promoting hormones (menopause)• Immobilization/lack of exercise• Genetics• Diet (calcium and vitamin D3)• Smoking and alcohol• Excess of hormones that cause bone resorption• Thyroid hormone• Corticosteroids
RISK FACTORS FOR OSTEOPOROSIS
• Age (affects ¼ of women over 50)• Race (highest in Caucasians)• Gender (more common in females)• Loss of growth promoting hormones (menopause)• Immobilization/lack of exercise• Genetics• Diet (calcium and vitamin D3)• Smoking and alcohol• Excess of hormones that cause bone resorption• Thyroid hormone• Corticosteroids
PREVENTION
• Dietary supplementation- calcium- vitamin D
• Exercise• Reduce factors leading to falls
TREATMENT
• Hormone replacement therapy-(side effects)
• Calcitonin• Alendronates (Fosamax)
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