Case Study 3

1.  osteopenia: decreased bone density vs. osteoporosis: progressive bone loss disease.
George may have osteopenia.
2. Osteoporotic fractures

1.   Define osteopenia and osteoporosis. Which does George seem to have?

Osteopenia is the net loss of bone in metabolic bone disease resulting from infection, tumor growth, abnormal ossification, or an imbalance in bone remodeling. Osteoporosis is the gradual and progressive loss of bone mass resulting physical inactivity, calcium, phosphate, and vitamin D deficiencies; heavy caffeine and alcohol ingestion; and smoking. George probably broke a few bones in his motorcycle accident which cause osteoclast formation, causing a loss in bone mass due to bone reabsorption. Due to his malabsorption issues with losing his kidney and some small intestine as well as his ability to go outside and be in the sun, he probably has calcium, phosphate, and vitamin D deficiencies. Combined with his inactivity level, he more than likely has osteoporosis.

2.   What is the most common type of fracture of the wrist in a person of George’s age?

Colles’ Wrist Fracture (According to the American Academy of Orthpaedic Surgeons) due to weakened bones

3.  Explain how Vitamin D, calcidiol, and calcitriol are synthesized?

The sun’s ultraviolent light on the skin produces Vitamin D (cholecalciferol) which is carried by the blood with a hyhdroxyl (OH) group to the liver and combined with an additional OH group to be modified into calcidiol. The kidney’s nephron tubules complete formation by adding another OH group and the hormone yields calcitroil. Once activated, calcitroil is principally taken up by the intestinal epithelium, where it indirectly promotes the active absorption of calcium from the lumen.

4.  How could George’s missing kidney be related to his decreased bone strength?

George’s missing kidney means that his body cannot secrete PTH which activates osteoclasts to make calcium available for bone reabsorption.
 
 5.  How could George’s partial small intestine be related to his decreased bone strength?

The small intestine epithelium promotes the active absorption of calcium from the lumen as calcitriol is increased due to increases in PTH. Missing part of his small intestine means George isn’t able to absorb calcium properly.

6.   If George has a decreasing density of his bones due to his previous injuries, what is the classification of his condition?

George has secondary osteoporosis

7.   Could George’s lack of time outside be a factor in his weak bones?

Yes; light from the sun interacts with a cholesterol derivative in the skin which produces Vitamin D