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... and when GH levels are normal, acromegaly may still be present by means of adenoma ta. The Role of Plasma Measurements of Growth Hormone and IGF-I in the Assessing Growth Hormone Secretion in Humans: This article summarizes how the peptide hormone GH controls the expression of the IGF-I complex then goes on to discuss ways in which the IGF levels are measured. The majority of the circulating Igf's exist in the liver where they bind to the IGF-I complex with a negative feedback response to the hypothalamus and pituitary gland. Complications with this structure result in excessively tall or short stature in children and possible acromegaly as adults. This article also argues that neither IGF levels nor IGFBP- 3 levels should be measured in random plasma tests.
This disputes the first two articles, which argue one method is better than the other. The pituitary gland produces GH in a pulsatile manner, so at any given time, the hormone level may be very high or very low. However, if the plasma were tested for IGF levels while the pituitary gland was producing GH at the persons maximum level, more accurate comparisons can take place. The Christchurch Department of Endocrinology tested a method in which the levels are measured before the test and after a clonidine stimulus is applied, forcing the GH level to rise to its maximum production rate. Unfortunately, this testing method is reasonably new and appears to be only accurate in growth hormone disorders excluding acromegaly. Acromegaly patients can be diagnosed through this new manner of screening, however many acromegalies will have growth hormone levels consistently within the normal range, so testing for IGF levels in any situation may prove unreliable.
Currently the Department of Endocrinology is continuing assessment of the benefits of this testing process. When age and advancement of the disease is taken into account, these tests tend to lose the benchmark at which diseased and healthy may be determined. Guidelines for the diagnosis and treatment of acromegaly: a Canadian perspective: This abstract from the Canadian Medical Association discusses the general symptoms noted which are commonly used for the diagnosis of acromegaly. Here it mentions that acromegaly is often the result of an adenoma, however it can also be the cause of benign pituitary adenoma ta.
Oftentimes, the disease is diagnosed after arthropathy diabetes, hypertension, cardiac dysfunction, obstructive sleep apnea, or colonic neoplasia occurs. These symptoms are irreversible and typically result in death. Acromegaliacs are also two to three times more likely to die due to the complications mentioned above. With growth hormone secretion regulation, the death rate of acromegalies tends to return to the normal range, which is why it is so important to diagnose acromegaly specifically and begin immediate and specialized treatment. Discussion: The five articles presented each discuss either the three proposed methods of testing for acromegaly, background information on the disease, or exceptions to what is commonly believed about acromegaly. The third and final articles are background-based commentary which set the stage for the first, second, and fourth articles, all of which debate the method of testing for acromegaly and other GH disorders.
Presently three methods exist in testing: IGF-I levels, IGFBP- 3 levels, and stimulus-plasma levels. Recent advancements have ruled out testing the amount of Igf's in the plasma, however the debate still continues as to whether IGF-I free or activated levels should be measured over IGFBP- 3 or stimulated GH levels. Depending on the disease, one test appears to work better than the other. The recent German study indicates that IGFBP- 3 levels do not correlate with acromegalies based on many limiting factors. Rather, the level of free IGF-I in the plasma for middle-aged persons shows the greatest differentiation. This directly contradicts the previous study which indicates that the level of IGFBP- 3 is the only reliable system of measurement since IFG-I levels change because of the pulsing manner of the pituitary gland.
The Christchurch study however argues that both methods of testing are inaccurate for that very reason; the pituitary gland does not function at a steady rate, so testing any level at any random time will not yield accurate results. The three studies agree that there are a few limiting factors involved in all of the experiments. Age and sex affect the levels of IGF-I, IGFBP- 3, and GH in the plasma, as does the advancement of the disease. This makes it difficult to establish benchmark levels based on age or gender; at any given moment the hormone level of a normal healthy person may fluctuate dramatically. Recently, research has been leaning towards difference studies where a level is tested before and after stimuli. The difference between stimulated and normal pituitary function tends to be the more favorable test, though this method also has major drawbacks including the major issue of how can one know whether the pituitary gland is functioning at a minimum level.
Using drugs which slow the GH production in the pituitary gland may be detrimental to a healthy person, so testing for acromegaly by these drugs is not safe nor recommended. The other problem with difference testing is that many patients with acromegaly do not have abnormal GH levels, as indicated in the Canadian study. Oftentimes, these patients have adenoma ta which can be removed through stereotactic radiosurgery, but not after major damage to the brain and gland have already occurred. For these patients, an entirely new form of testing must take place where growth hormone levels alone are not the sole indicator of disease.
Another problem with this testing is that if a minimum and maximum productivity level are found, what levels should be tested. This ties into the first two articles which discuss IGF-I freebsd levels versus IGFBP- 3 level testing. Both of these levels are affected dramatically by age and sex, however it appears both levels may need to be tested for accurate results regardless. The German study indicates testing for IGFBP- 3 is more acromegaly-specific, but IGF-I testing tends to determine GHD. These being the circumstances, research is being conducted where IGF-I levels are tested and followed up by IGFBP- 3 testing for potential acromegaly-specific cases.
Conclusion: Since acromegaly is often difficult to diagnose until later in life, recent studies are focusing on the best and most efficient way to determine a problem before major irreversible damage occurs. Unfortunately, since the disease is so rare, major symptoms generally have to occur before the afflicted is even tested for the disease. However, it is also hereditary and with heredity comes early testing in patients where the disease is prevalent among the family. The problem arises then as to how to test early since growth hormone therapy performed on a patient who does not definitely have the disease may be more damaging than leaving the actual disease untreated. The rarity of the disease however, tends to limit the fund which go into the research, making early testing difficult to advance. Since it is known that age, sex, and advancement of the disease affect hormone and receptor levels, it is clear that more research must be done in order to establish what is normal for comparison with potentially diseased persons.
The majority of the acromegaly and GHD research funds are currently being poured into investigations on how to slow the pituitary gland without damaging it or the patient. GHD therapy includes medication which slows the pituitary gland, but in a healthy person, this type of treatment may even be fatal. Again, more research is being conducted to create a safe way to temporarily slow down pituitary function for this purpose. In addition, research is also being conducted as to whether IFG-I free or IGF-I total measurements should be taken since the values tend to fluctuate; also IFGBP- 3 levels should be tested for acromegaly-specific cases. In both situations, further research must be conducted to establish average healthy and abnormal ranges in both levels.
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Research essay sample on Pituitary Gland Growth Hormone
