PP: Mobility

The Role of Calcium in the Body

• Calcium Importance

  • Essential for numerous bodily functions including the nervous, muscular, and cardiovascular systems

  • Primary mineral responsible for bone formation and maintenance of bone health throughout the lifespan

Calcium Levels and Homeostasis

• Normal Calcium Levels

  • Normal range: 8.5 to 10.5 mg/dL (varies slightly by laboratory)

• Regulation of Calcium Levels

  • Hormones Involved:

  • Parathyroid Hormone (PTH)

    • Released when blood calcium levels are low

    • Raises calcium levels through:

    • Stimulating bones to release calcium

    • Increasing calcium absorption in kidneys, reducing loss in urine

    • Activating vitamin D to enhance intestinal calcium absorption

  • Calcitonin

    • Released by the thyroid gland when blood calcium levels are high

    • Lowers calcium levels by:

    • Inhibiting bone breakdown

    • Reducing calcium release from bones

    • Increasing calcium excretion in kidneys

  • Vitamin D

    • Supports calcium absorption from the intestine and works with PTH to maintain calcium balance

Vitamin D Metabolism

• Inactive Form of Vitamin D

  • Cholecalciferol (Vitamin D3) is synthesized from cholesterol in the skin due to sunlight exposure or obtained from dietary sources

  • After absorption, converted by the kidneys to calcitriol, the active form of Vitamin D

• Clinical Importance

  • Patients with kidney disorders may struggle to synthesize calcitriol, leading to calcium and Vitamin D abnormalities

Calcium's Role in Neuromuscular Function

• Calcium Ions and Neuron Excitability

  • Calcium ions influence the excitability of neurons, aiding in nerve transmission

Hypercalcemia (High Calcium Levels)

• Definition: Excess calcium in the blood

• Causes:

  • Hyperparathyroidism (overactive parathyroid glands)

  • Certain cancers (e.g. lung, breast, blood cancers)

  • Excessive Vitamin D intake

  • Some diuretics

  • Dehydration

• Signs and Symptoms: May be mild or asymptomatic, but can include:

  • Fatigue, weakness, confusion, constipation, abdominal pain

  • Frequent urination, excessive thirst, bone pain/fractures

  • Potential development of kidney stones and heart problems (arrhythmias)

Hypocalcemia (Low Calcium Levels)

• Definition: Insufficient calcium in the blood

• Causes:

  • Vitamin D deficiency

  • Hypoparathyroidism (underactive parathyroid glands)

  • Chronic kidney disease

  • Magnesium deficiency

  • Some medications, such as bisphosphonates

• Signs and Symptoms:

  • Muscle cramps or spasms, tingling sensations

  • Fatigue, weakness, seizures, heart problems, confusion or memory loss

  • Notable clinical signs: Trousseau's sign (hand spasm when BP cuff inflated); Chvostek's sign (facial twitching when tapped near the ear)

Pharmacotherapy for Hypocalcemia

• Importance: Hypocalcemia is not a disease but a sign of underlying issues

• Nutritional Interventions: Increasing calcium and vitamin D rich foods

  • Dairy, fortified orange juice, cereals, green leafy vegetables (except spinach due to oxalates)

• Calcium Salts: Prototype drug for calcium supplementation used in various conditions such as chronic hypocalcemia, osteoporosis, Paget's disease, osteomalacia, and rickets

  • Administer orally with food or within an hour after eating for best absorption

  • IV administration must be slow to avoid serious complications, including hypotension and cardiac arrest

Metabolic Bone Diseases

• General Definition: Cluster of disorders resulting in defects in bone structure due to inadequate minerals or hormones

Osteoporosis

• Definition: Most common metabolic bone disease, leading to fractures, particularly in postmenopausal women

• Mechanism: Bone resorption occurs at a higher rate than deposition, resulting in brittle bones

• Risk Factors: Menopause, advancing age, family history, excessive alcohol consumption, smoking, lack of exercise, low levels of estrogen and vitamin D, use of corticosteroids

Osteomalacia

• Definition: Softening of bones due to inadequate mineralization

• Causes: Vitamin D and calcium deficiencies; more prevalent in older adults, premature infants, or strict vegetarian/vegan diets

• Signs & Symptoms: Hypocalcemia, muscle weakness, diffuse bone pain

Paget's Disease

• Definition: Characterized by accelerated bone remodeling leading to enlarged and softened bones

• Mechanism: High rates of bone resorption and deposition result in weak and brittle bones

• Symptoms: Often asymptomatic but may include pain in hips, joint inflammation, and potential complications like arthritis and kidney stones

Vitamin D and Calcium Supplementation Therapies

• Vitamin D (Calcitriol): Promotes intestinal absorption of calcium; protect from light and heat; monitor breastfeeding and potential fetal harm

• Bisphosphonates (e.g., Alendronate/Fosamax): Prevents and treats osteoporosis; administer on an empty stomach with plain water; must remain upright post-ingestion; potential side effects include gastrointestinal pain and fractures; risk of osteonecrosis of the jaw

• Selective Estrogen Receptor Modulators (SERMs): Raloxifene (Evista) decreases bone resorption, improves bone mass and density with side effects including hot flashes and weight gain; carries black box warning for increased thromboembolic events

Teaching and Patient Management

• Patient Education:

  • Administer medications appropriately according to guidelines

  • Monitor for signs and symptoms of calcium abnormalities

  • Promote lifestyle changes to support bone health, including exercise and diet adjustments

Patient Case Presentation: Mrs. Anderson

• Demographics: 67-year-old postmenopausal woman with a fractured hip

• Health History: Hypertension managed with lisinopril; smoking and sedentary lifestyle; low serum calcium and vitamin D levels

• Rationale for Risk:

  • Age, postmenopausal status, smoking, prednisone use, and low calcium/vitamin D levels increase osteoporosis risk