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)