Abnormal Bone Development by Jordan Pfaff

From birth to death, the Human body undergoes many changes, especially during childhood. One of the many changes that are most visible has to deal with bone growth. In addition to supporting the heart and other vital organs, bones govern how tall an individual is and the shape of certain facial features such as cheeks and chin. Thus, when abnormal bone growth occurs, its effects are easily visible. The two bone growth conditions that are the subject of this paper are Acromegaly and Gigantism.

Acromegaly and Gigantism are very similar in the way they are caused, and yet they have very different symptoms.  Both Acromegaly and Gigantism arise due to an over secretion of Growth Hormone from the anterior pituitary gland. The most likely cause for this to happen is a tumor, usually benign, located on the pituitary gland called an Adenoma. This tumor causes growth hormone (GH) to be released in excess. The main difference between Acromegaly and Gigantism however comes from when GH is released.

The timing of the excess release of GH governs which condition will take place. It all comes down to whether or not the epiphyseal plate is closed or not which is dependent on age usually. The epiphyseal plate is a plate made of hyaline cartilage that is found at the ends of long bones such as the femur for example. This plate is only found in young adults and children and is the site of normal bone development. As the bone grows, the cartilage is replaced by bone until all of the cartilage is used up. At that point bone growth stops, usually around puberty.

Because Growth Hormone is one of the controlling factors in bone development in the extension of the epiphyseal plate, an excess will lead to longer bones in adolescents. This is when Gigantism occurs. The Adenoma on the anterior pituitary causes the release of GH, which signals the growth of bone to the epiphyseal plate. Since the plate is still open and has room to grow, an extension will occur. This leads to the individual increasing in height dramatically. People with Gigantism usually grow between 7 to 9 feet tall. This can lead to many health problems, most dealing with circulatory and skeletal issues.

Acromegaly on the other hand does not make an individual taller. Acromegaly occurs when the abnormal release of Growth Hormone takes place after the epiphyseal plate has closed, typically in adults. Instead of lengthening the long bones, Acromegaly makes certain bones thicker and more pronounced. Most often the hands, jaw, and forehead are affected. In addition, Acromegaly leads to teeth to be spaced out more due to the abnormal bone growth in the jaw region.

Treatments for Gigantism and Acromegaly have the same goal: to return Growth Hormone levels to normal. This normally is achieved by removal of the Adenoma through surgery. If surgery isn’t enough or cannot be done safely, then drugs like lanreotide or octreotide, or radiation therapy can help reduce GH levels to normal. Although the symptoms of Gigantism or Acromegaly may not seem serious, treatment is necessary. If left unchecked, these conditions may lead to heart and kidney failure.

In conclusion, over development of bone can be hazardous to the human body. While being taller might seem like a good idea, an excess amount of growth is quite the opposite. Also, while the cause of excess bone growth is important, the timing is even more so. Whether a bone grows longer or thicker is all dependent on timing relevant to the stage of development. All of this caused, no less, from a bit of extra Growth Hormone.

 

References

NHI: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002157/

Wikipedia:  http://en.wikipedia.org/wiki/Acromegaly

Medscape: http://emedicine.medscape.com/article/925446-overview

UMM: http://www.umm.edu/ency/article/001174all.htm