Pituitary Abnormality Causing Dwarfism, Giantism, or Acromegaly

One of the most common hormone produced by the pituitary is the growth hormone. The pituitary is a small, pea-sized gland located in a bony area behind the bridge of the nose called the sphenoid bone.

The growth hormone produced by the pituitary gland is responsible for the growth of different body cells including muscles and bones. It is the primary hormone responsible for the growth of different organs of the body including growth in length of long bones, such as the arm, thigh and leg bones in young people. In addition, growth hormone promotes breakdown of lipids (fats) for production of energy and increase blood sugar levels.

Problems associated with growth hormone secretion by the pituitary can occur when too much or too little of the hormone is produced. Two common problems associated with too much production or secretion of growth hormones are giantism and acromegaly.

Giantism, also called gigantism, occurs when excess growth hormone is released by the pituitary during the growth years of the person. This can occur when there are tumor cells in the pituitary, which can make it produce more growth hormone.

Because the long bones are still growing in length, the person having too much growth hormone can cause these long bones to become longer than normal. As a result, the person grows very tall. The person with giantism usually has proportionate body.

People with the condition may have elevated blood sugar and possibly diabetes. This may be due to the function of the growth hormone that can elevate blood sugar levels.

When growth hormone is produced in excess during adulthood, it can lead to a condition called acromegaly. Too much production of growth hormone that causes acromegaly may be due to a tumor in the pituitary gland.

Because long bones have already stopped growing in length, acromegaly does not affect lengthening of bones like what happens in growing bones. However, the condition can cause the bones of the hands, feet, jaw, and cheeks to become thick or enlarged. Also, people with acromegaly may have enlarged eyelids, lips, tongue and nose. In some people, their skin may be thickened and sometimes develop furrows, which can occur on the forehead and soles.

Just like in giantism, people with acromegaly may have high blood sugar, particularly caused by the elevated growth hormone.

Too little growth hormone secretion happening during the growth years can cause dwarfism. Bone growth slows down and the area where bone growth in length occurs closes even before normal height is achieved. Normal growth of other organs is hampered as well. A person affected with dwarfism remains child-like.

When the condition is detected early and when growth areas in the bones have not yet closed, administration of man-made growth hormone can help.

References:

Tortora, G. and Grabowski, S.: PRINCIPLES OF ANATOMY AND PHYSIOLOGY. 10^th ed. John Wiley and Sons, Inc., 2003.

Seeley, R. et al: ESSENTIALS OF ANATOMY AND PHYSIOLOGY. 5^th ed. McGraw - Hill, 2005.

Acromegaly. National Institute of Diabetes and Digestive and Kidney Disease (NIDDK).