Osteoporosis: Marissa, Jeremy and Eleanor, Case Study Example

Marissa

The bone remodeling cycle is a very intricate process that involves several highly structured stages. During the first phase of the remodeling process, “activation”, mononuclear pre-osteoclasts attach to the surface of the bone. At the site of attachment, the pre-osteoclasts fuse together to form large multinucleated bone cells, called osteoclasts. The osteoclasts are distinguishable by a ruffled and bumpy membrane when compared to the older bone surface. The second stage is the “resorption” phase. During this phase, the osteoclasts become acidified and as a result, slowly dissolve the structure of the bone. This results in deep fissures called cutting cones, which release calcium into the blood for other functions. Osteoclasts become smaller once resorption stage is finished. The third stage is the “reversal” phase. During the reversal phase, a sticky sugary cement is produced to help the old bone to fuse to the new bone.  The next phase is the “formation” stage. In this stage, precursors of the osteoblasts, called osteoprogenitor cells begin to line the cavities formed by the osteoclasts. These precursor cells divide and increase in number through the process of mitosis to later become osteoblasts. The function of the osteoblasts is then to deposit into the fissures, bone matrix that has not been mineralized, called osteoid. The osteoblasts are then pushed toward the bone’s surface by the matrix composed of osteoid. The last phase is the calcification stage.  During calcification phase, calcium and phosphorus change the osteoid into mineralized bone.

Calcium is a mineral that is important for bone strength and in the process of remodeling. During remodeling, small amounts of calcium is removed from the bones and replaced with new calcium. However, if more calcium is removed than is being replaced, bones become weaker and more likely to break. Up until the end of the teenage years, calcium is stored in the bones provided from eating calcium rich foods. By age 30, the bones will not continue to replenish calcium stores. At this point, calcium levels can only be maintained through diet alone.

The amount of calcium in the body is controlled by two different hormones. The parathyroid hormone is the regulator of the level of calcium in the body. The four parathyroid glands are only about the size of a grain of rice, but they are crucial to nervous and muscular functions. This hormone regulates the amount of calcium that is absorbed from foods, excreted by the kidneys, and stored in the bones. This process is controlled by increasing the amount of vitamin D, which increases intestinal calcium. In a parathyroid disorder, too much PTH can be released. This can result in too much calcium being released into the blood stream. Calcitonin is a hormone that is involved in the process of calcium metabolism. The major source of calcitonin comes from the thyroid gland. However, it is also produced in the lungs and the intestinal tract. Calcitonin can hinder bone formation by prohibiting osteoclasts from releasing calcium and phosphorus into the blood. Calcitonin also inhibits tubular reabsorption of calcium and phosphorus by the kidneys, instead causing an increase of their loss in urine.

Osteoporosis is a metabolic bone disorder. It affects the bone matrix and the remodeling process of bones. Osteoporosis is the result of the bone’s resorption stage out working the bone’s formation stage. Bone formation is the stage of the remodeling process in which osteoblasts create new bone. To the contrary, resorption is the stage where osteoclasts remove bone. In osteoporosis, osteoclasts out work the osteoblasts, resulting in weakened bones.

Osteoporosis is at an increased chance of occurring if there is positive family history. So far, fifteen confirmed genes and thirty suspected genes have been related to osteoporosis. Scientists have identified three pathways, the estrogen endocrine pathway, the Wnt/B-catenin signaling pathway, and the RANK/RANKL/osteoprotegerin pathway.

Risk factors for osteoporosis include, age, sex, diet, amount of physical activity, types of medications, menopausal status, and genetics.

Sometimes there are no symptoms of osteoporosis. But when there are, they include backache, a gradual loss of height, a stooped posture, and fractures of the spine, wrist, or hip.

Jeremy

Calcium is important to bone health for one main reason. Calcium along with phosphorus is what mineralizes osteoid in the formation of new bone by the osteoblasts. Calcium is essential to new bone becomes strength and durability. Without enough calcium, bones become brittle and weak.

There are many food sources that are rich in calcium. Some of these include, greens, kale, broccoli, soy beans, oranges, sardines, shrimp, cheeses, yogurts, ice cream, oatmeal, and certain types of cereals.

Vitamin D is essential to calcium absorption because vitamin D produces the hormone calcitriol. Calcitriol stimulates calcium absorption from the stomach into the blood stream.

The daily recommendations of daily calcium intake is 1000milligrams to 1,200mgs in most adults including, mgs pre-menopausal and post-menopausal women on estrogen. For lactating or pregnant women it is 1500 mg per day.

The levels of calcium in the body is affected by many things. Sodium affects the amount of calcium in the body based on urinary calcium loss. High levels of sodium compete with calcium for reasbsorption by the kidneys. More sodium chloride excreted by the kidneys is correlated with more calcium loss through urine. However, caffeine has been found to not significantly affect calcium absorption or excretion levels, as long as the amount of consumption wasn’t excessive. Alcohol, on the other hand, can significantly affect bone health and increase the risk of osteoporosis. Alcohol interferes with the pancreas and the liver. Both of these organs play a role in relationship of vitamin D and calcium.

Peak bone mass is the amount of bone tissue in the skeleton at the end of maturation. During peak bone mass, bones obtain maximum strength and density. It is after peak bone mass that osteoporosis develops for some individuals. This is the period where bones start withdrawing stored calcium to be used by the body if diet doesn’t provide enough. This is how brittle bones occur.

There are preventive exercises for osteoporosis. High impact exercises like dancing, hiking, jogging and stair climbing help build bones density and strength. Low impact exercises also help bones to stay strong. Muscle building exercises like weight lifting helps to provide more protection for bones.

Steroids are synthetic hormones designed as medical treatments. There are two types. Anabolic steroids resemble testosterone and promote growth of muscle. Corticosteroids treat allergic reactions and autoimmune diseases.

Long term steroid use can significantly affect metabolism of calcium, vitamin D, and bone. Steroids can cause osteoporosis by interfering with bone matrix mineralization and causing apoptosis of osteoblasts.

Eleanor

Perimenopausal is the time period in which a woman starts to make the transition toward becoming permanently infertile (menopause).

Menopause affects a woman’s hormone levels causing many changes. As estrogen and progesterone levels decline, the body’s metabolism slows.

Low levels of estrogen hinders the absorption level of calcium which can result in osteoporosis. One of the major functions of estrogen is to inhibit bone resorption. Without estrogen, resorption will occur more rapidly.

Smoking has been found to lower levels of estrogen in women and men. Smoking increases the risk of osteoporosis by lowering the level of estrogen. Smoking causes a lower absorption rate of calcium from the stomach.

HRT is hormone replacement therapy. HRT (estrogen and progesterone) is targeted for menopausal women as a means of relief for their symptoms.

The pros of hormone replacement therapy is that they are effective in relieving the symptoms of menopause. The cons of HRT is that there is an increased risk of breast and uterine cancer, heart attack and stroke.

Two alternative drugs from the class bisphosphonates is Fosamax and Actonel. Both of these drugs are commonly used to treat osteoporosis in menopausal women. Because they do not contain estrogen, they do not carry the increased risks of cancer. Evista is from a class of drugs called selective estrogen receptor modulators. It is used to prevent osteoporosis and even helps to build new bones. A last alternative is Miacalcin. This drug treats osteoporosis in post-menopausal women who cannot take HRT.