Mandy is a 16-year-old competitive figure skater who practices several hours a day with her coach at the skating arena. Because of her extremely active lifestyle and restricted diet to maintain her athletic physique, she experiences ongoing amenorrhea. One day during practice, she landed a jump and fell to the ice in pain. Her left foot swelled up almost immediately, making it difficult for her coach to remove the skate. At the hospital, radiographs revealed a fracture of the fifth metatarsal bone and general radiolucency of all the bones in her foot. A follow-up DXA revealed a bone mass of 2.7 standard deviations below mean.
What is the etiology of Mandy’s premature osteoporosis, and how is her condition thought to contribute to a decrease in bone density?
Knowing what you do about bone mineralization, why does a deficiency of estrogen in women lead to osteoporotic change?
Osteoporosis and osteomalacia both involve abnormal bone mineralization. What are the general macroscopic differences between these two conditions?
The Etiology of Mandy’s Premature Osteoporosis, And How Her Condition Contribute to A Decrease in Bone Density
Osteoporosis refers to a systematic skeletal disease that is characterized by a decrease in bone mass and an impaired bone microstructure (Marcucci & Brandi, 2015). Bone strength becomes compromised, resulting in an increased risk of fractures. Diagnosing osteoporosis requires measuring bone mineral density through dual-energy X-ray absorptiometry of the forearm or the spine. There several pathogenic mechanisms, including aspects of bone metabolism such as an increase in bone resorption, decreased bone formation, abnormal collagen synthesis, and altered calcium, vitamin D, or phosphorus homeostasis. Various factors increase the risk of premature osteoporosis, including sex hormones as low sex hormones, especially low estrogen levels, weakens the bone. Eating disorders, which may lead to restriction of food intake and being underweight, are also risk factors. Calcium plays a great role in osteoporosis. Low intake of calcium leads to a decrease in bone density, early bone loss, and increases the risk of fractures (Marcucci & Brandi, 2015). Other factors include medication such as prednisone and use of steroids, medical conditions such as lupus, and lifestyle choices, including tobacco use and sedentary lifestyle. In the case of Mandy, premature osteoporosis is caused by her restrictive diet, amenorrhea, and being underweight as the factors limit the level of calcium in the body.
Using the Knowledge of Bone Mineralization, Why Does a Deficiency of Estrogen in Women Lead to Osteoporotic Change
Bone mineralization involves filling the organic bone matrix with calcium phosphate nanocrystals (Dey, 2020). The osteoblasts mediate the process, while the process is restricted to the organic osteoid matrix produced by osteoblasts. The bone cells, including osteoblasts, osteoclasts, and osteocytes, have estrogen receptors on the surface, and a deficit in estrogen results in less activity of the bone cells. A deficit in estrogen results in excessive bone resorption and inadequate bone formation. Decreased estrogen levels increase osteoclasts while reducing the number of osteoblasts leading to overall bone resorption (Okman-Kilic, 2015). Estrogen also has an indirect impact on bones through local growth factors and cytokines. Osteoporosis occurs due to an imbalance between bone formation and bone resorption. In the pathogenesis of osteoporosis, transcription factor PU.1 aid the osteoclasts to destroy the bone matrix while osteoblasts facilitate the formation of bone matrix. A decrease in bone mass density occurs when the osteoclast aids the destruction of the bone matrix faster than the rate of bone formation by the osteoclasts. There are three mechanisms of osteoporosis, which include excessive bone formation, insufficient peak bone mass, and insufficient formation of new bones. Hormonal factors impact the rate of bone resorption (Marcucci & Brandi, 2015). A deficit in estrogen increases the rate of bone resorption while decreasing the rate of deposition of a new bone.
The General Macroscopic Differences Between Osteoporosis and Osteomalacia
Osteomalacia describes a bone disorder known as ‘bone softening’ that occurs in adults due to prolonged vitamin D deficiency. The condition is characterized by a deficit of bone mineralization with the occurrence of a loss in the bone matrix. The depletion in bone minerals may be as a result of lack of diet vitamin D, exposure to sunlight, and impaired function of the liver, which is mainly involved in the absorption of on bone minerals, or abnormal bone mineralization process. The condition involves bones, not hardening. The condition indicates failure of osteoid to calcify (Zimmerman & McKeon, 2020). Osteoporosis, on the other hand, refers to the weakening of the bones. It involves a decrease in the bone mass and bone mineral density or a change in the structure of the bone. This reduces the strength of the bone, increasing the risk of fractures. The condition occurs due to an imbalance between bone resorption and bone formation.
Osteomalacia is signified by stiffness, trouble while getting up from sitting or walking up the stairs, muscle weakness on the thighs and arms, pain, feeling tired, and having easily broken bones. Major signs of osteomalacia include muscle weakness and fragile bones. Osteoporosis, on the other hand, is evident through the risk of fractures and curving of the back. Although osteoporosis has no symptoms in the early stages, weakening bones may result in a decrease in height over time, back pain that may be due to collapsed vertebra, and a stooped posture.
Osteoporosis causes the bones to become weak, fragile, and brittle to the extent that a fall or mild stress such as coughing or bending can result in a bone fracture. The condition occurs when the creation of new bones does not match the loss of old bone or bone resorption. The likelihood of the risk of individual developing osteoporosis depends on the bone attained in the youth. Adolescents, however, have a risk of developing osteoporosis due to certain risk factors such as low sex hormones, dietary factors, medical conditions, and medications. Mandy developed osteoporosis due to her restrictive diet, low levels of estrogen, and being underweight. While osteoporosis refers to bone weakening, osteomalacia refers to the failure of the bone to harden.