Do You Think That Drug Testing Should be Done as a Requirement for Admission to Schools? Why or Why Not?
I can say that I strongly agree with this statement that drug testing should be done as a requirement for admission to schools. Nowadays I recognize that drug and alcohol abuse represents an emerging problem in society. Most of the population involved in this kind of problems are students in our society, thats why the schools has to be aware of this kind of problem and must perform a fundamental role to control and manage this problem. Having this kind of screening to the students may somehow help to reduce and control the abuse of drugs. But the major disadvantage is that enrolees will subsequently decrease in number which the school obviously does not want to happen. One major problem that this task may encounter is the confidentiality of the results must be strictly keep in privacy. But despite this disadvantages I think it will be helpful for all of us if drug testing will be implemented in every school in our society and bring awareness to each and every people.
-It’s the physiological inhibition loop controlling most of the endocrine hormones. In negative feedback, any change or variation from the normal range of function is divergent, or resisted. The change or variation in the controlled value signals the response that brings the function of organ back within the normal range. The mechanism primarily depends on factors which manipulate the metabolism and flow of the hormones. Therefore, the high concentration of the hormone alone will not trigger the negative feedback mechanism because it must be triggered by the effect and result of overproduction on the hormone.
A simple example of an endocrine feedback loop is the hypothalamic-pituitary-thyroidal axis. The hypothalamus produces the hypophysiotropic hormone, thyrotropin-releasing hormone (TRH), and releases it into the portal system where it directs the thyrotrophs in the anterior pituitary to secrete thyroid-stimulating hormone (TSH). TSH circulates to the thyroid and stimulates several steps in the thyroid that are critical in the production and release of thyroid hormone. Thyroxine is released in the blood and circulates to the hypothalamus and pituitary to suppress further TRH and TSH production.
References: Fundamentals of Clinical Chemistry by Bishop et al
Clinical Laboratory Diagnosis by John Bernard Henry et al (19th Edition)
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1. What stimulate the release of the somatotropin from the pituitary gland?
2. The secretion of growth hormone is at its peak during ________.
3-4.Give two conditions which are caused by decreased levels of growth hormone.
5. Enhanced protein synthesis in this site is caused by theanabolic effects of growth hormone.
6. A coarse thickening of the bones of the skull, hands and feet over the course of years to decades.
7. An autosomal recessive disorder characterize by insensitivity to growth hormone, caused by a deviation of the growth hormone receptor. This disorder is associated with increased levels of GH.
8. Normal values of growth hormone in adult males?
9. Growth hormone is secreted in pulses, with an average interpulse interval of____ hours?
10. Obesity and the use of many drugs will cause false _______ result in the growth hormone suppression test.
Case Study
A 48-year-old man seeks care for evaluation of muscle weakness, headaches, and excessive sweating. He has poorly controlled hypertensionand, on questioning, admits tonoticing a gradual increase in both glove and shoe size, as well as a reduction in libido. A review of older photographs of the man documents coarsening of facial features, progressive prognathism and broadening of the nose. Acromegaly is suspected.
Questions:
1.What screening tests are available?
2.What is the definitive test for autonomous growth hormone production?
3.Because the patient complains of reduced libido, hypogonadism is suspected. What evaluation is appropriate?
Growth hormone, also known as somatotropin for its growth-promoting effects on the body, also abundant hormone of the anterior pituitary. The major physiological effects of GH are anabolic: promoting protein synthesis, lipolytic, stimulating fat breakdown, lactogenic, diabetogenic by increasing resistance to insulin. Somehow, it also has intrinsic insulin-like hypoglycemic activity. Release of somatotropin from the pituitary is stimulated by the hypothalamic peptide growth hormone-releasing hormone (GHRH); somatotropin’s secretion is inhibited by somatostatin.
Growth hormone is secreted in pulses, with an average interpulse interval of 2-3 hours, with the most reproducible peak occurring at the onset of sleep. Complete absence of GH slows the rate of growth to only one third to one half of normal. Abnormally elevated levels lead to gigantism. In the adult patient with GH excess, no effects are seen in the long bones after the epiphyseal growth plates have fused. Instead, GH excess gradually produces acromegaly, a coarse thickening of the bones of the skull, hands and feet over the course of years to decades.
Functions of the Growth Hormone
Growth hormone has many diverse effects on metabolism; it is considered an amphibolic hormone because it directly influences both anabolic and catabolic processes. Increased height during childhood is the most widely known effect of GH.
Addition to increasing height in children and adolescents, growth hormone has many other effects on the body:
Human growth hormone (somatotropin, hGH) is essential to the growth process and has an important role in the metabolism of adults. It is secreted by the pituitary gland in response to exercise, deep sleep, hypoglycemia, glucagon, insulin and vasopressin. It also stimulates the production of RNA, and is intimately connected with insulinism. If the pituitary gland secretes too little or too much hGH in the growth phase of life, dwarfism of gigantism will result, respectively. An excess of growth hormone ducring adulthood leads to acromegaly.
This test confirms hypopituitarism or hyperpituitarism so that therapy can be initiated as soon as possible. Challenge or stimulation tests are generally used to detect hGH deficiency and are more informative. Much controversy surrounds the use of the growth hormone stimulation tests and the diagnosis should be considered in the context of the clinical picture.
Reference Values
Normal
Men: <5ng/ml or 226 pmol/L
Women: <10ng/ml or 452 pmol/L
Children: 0-20 ng/ml or 0-904 pmol/L
Newborns: 5-40 ng/ml or 226-1808 pmol/L
Stimulation test (using arginine, glucagon or insulin)
>5 ng/ml or 226 pmol/L (rise from baseline)
>10ng/ml or 452 pmol/L peak response from baseline
Suppression test (using 100 g glucose)
0-2 ng/ml or 0-90 pmol/L or undetectable
Clinical Significance
Increased hGH levels are associated with the ffg conditions:
a.Pituitary gigantism
b.Acromegaly
c.Laron’s dwarfism (hGH resistant)
d.Ectopic GH secretion
e.Uncontrolled Diabetes Milletus
Decreased hGH levels are associated with the ffg conditions:
a.Pituitary dwarfism
b.Hypopituitarism
c.Adrenocortical hyperfunction
Interferring Factors
Increased levels are associated with the use of oral contraceptives, estrogens, arginine, glucagon, levadopa, low glucose and insulin.
Levels will rise to 15 times normal by the second day of starvation; levels also rise after deep sleep, stress, exercise and anorexia.
Decreased levels are associated with obesity and the use of corticosteroids.
Many drugs interfere with the results
Recently administered interfere with the test results
Growth hormone suppression
Also called glucose loading, the growth hormone suppression test evaluates excessive baseline levels of hGH from anterior pituitary gland. Normally glucose and fatty acid aoncentrations; in response, insulin secretion increases to counteract these effects.
Purpose
-To assess elevated baseline levels of hGH
-To confirm diagnosis of gigantism in children and acromegaly in adults and adolescents
Reference Values
Normally, glucose suppresses hGH ti levels ranging from undetectable to 3 ng/ml(SI, 3 ug/L) in 30mins to 2hrs.
Abnormal findings
In a patient with active acromegaly, elevated baseline levels of hGH (5 ng/ml) aren’t suppressed to less than 5ng/ml during the test. Unchanged or rising hGH levels in response to glucose loading indicate hGH hypersecretion and may confirm suspected acromegaly and gigantism. This response may be verified the test after a 1-day rest.
Interfering factors
Failure to observe pretest restrictions
Hemolysis due to rough handling of the sample
Corticosteroids and phenothiazines such as chloropromazine
Radioactive scan performed within 1week before the test
Delay in sending the specimen to laboratory
References
John Bernard Henry 19th edition pages 323-328
Clinical Chemistry by Michael Bishop pages 402-403
A manual of laboratory and diagnosis tests 7th edition by frances fischbach pages 369-371
