Calcium and Bone

CALCIUM & BONE METABOLISM

Parathyroid glands are located in the neck on the rear tip surfaces of the thyroid gland. Parathyroid gland produces

  • Parathyroid hormone which increases blood calcium by
    • Stimulating osteoclasts to break down bone
    • Increase absorption of calcium in gut by activating Vitamin D
    • Promote reabsorption of calcium by kidneys
    • Deficiency occurs due to neck surgery, genetics and autoimmune disorders resulting in
      • HYPOPARATHYROIDISM
      • Symptoms to include distal extremity numbness and tingling, carpopedal spasm, seizures, irritability, confusion, delirium, tetany, heart failure, wheezing, stridor, low blood pressure (hypotension)
    • Excess production due to adenoma, familial/genetic or drug induced (lithium)
      • HYPERPARATHRYOIDISM
      • Symptoms include:  kidney stones, decreased bone mass (osteopenia), weakness, fatigue, psychosis, constipation, excessive urination (polyuria), excessive thirst (polydipsia), and nausea.  
  • Calcium disorders
    • Elevated Calcium (Hypercalcemia) can be due to
      • Hyperparathyroidism, Cancer, Granulomatous disease (Tb, Sarcoid), hyperthyroidism, immobilization, medication.
    • Low Calcium levels (Hypocalcemia) can be due to
      • Hypoparathyroidism and Vitamin D deficiency

BONE HEALTH:  
Osteoporosis is a disease of the bones that leads to increased risk of fracture. In osteoporosis, bone mineral density is reduced.

  • Risk factors include
    • Advanced age, female sex, Caucasian background, family history, low body weight, excessive alcohol intake, insufficient intake of Calcium and Vitamin D,  Early menopause (age<45), premature ovarian failure, medical/surgical menopause, steroid and medication use, rheumatological disorders, malabsorptive disorders 

Osteomalacia in adults is a mineralization disorder in which structural integrity of the bond is reduced because of deficient supply of calcium to bone surface.

  • Risk factors include
    • Very low Calcium intake, calcium malabsorption (i.e. celiac disease), phosphorus deficiency, some types of cancer and  lack of sunlight resulting in Vitamin D deficiency

Paget Disease of Bone is a disorder of osteoclast over activity resulting in formation of mechanically ineffective woven/repaired (instead of lamellar) bone.

  • Symptoms include bone pain, fracture, paraplegia, deafness, shortness of breath (high output cardiac failure)

Disclaimer: This page is intended for general information and does not substitute for medical recommendations from your health care provider.