question archive A 67-year-old retired male went to his doctor, complaining initially of leg pain that started in his lower back, which then radiated down across the side of his thigh and over the front of his knee
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A 67-year-old retired male went to his doctor, complaining initially of leg pain that started in his lower back, which then radiated down across the side of his thigh and over the front of his knee. Subsequently, he developed pain that radiated from his back to his front at two different levels: at the chest through the level of his nipples and also at the umbilicus.
His physician performed a history and physical, followed by laboratory tests. He discovered a hard nodule on his prostate and an elevation in several of the blood tests. His PSA (prostate specific antigen), an enzyme secreted by normal prostate tissue (0-4 ng/ml) was 450. Alkaline phosphatase was also elevated at 157 U/L, an indication of bone involvement.
A bone scan was ordered to visualize the bone involvement. (This test uses a calcium analogue attached to a radioactive tag. A special scanner can pick up images of this radioactivity and create an anatomical picture of the skeletal system. The radiation shows up as black spots on the film.)
Usually prostate cancer's growth is initially influenced by the presence of testosterone. If testosterone is removed by castration, the cancer will often shrink for some period of time before the remaining fraction of testosterone-independent cancer cells grow.
This gentleman was not interested in castration and asked if there was another way to treat this. He was treated was a single shot of a drug which is slowly released into the body over a three month time period. Within that time the patient noticed marked relief in his pain.
1. What is the diagnosis of this gentleman?
2. Why would the scan show bone abnormalities?
3. Which endocrine organs are responsible for serum calcium levels?
4. Describe the feedback loop between the anterior pituitary and the production of testosterone in the testes.
5. Describe a mechanism by which a drug could act on the anterior pituitary to lower the testosterone level in the human body.
Answers:
?1) The diagnosis for this gentlemen is prostate cancer
?2) Bone abnormalities is due prostate cancer metastabilizing to the bone.
?3) The parathyriod hormone is secreted by the parathyriod glands, is responsible for regulating blood calcium levels.
?4) GnRH from the hypothalamus stimulates LH release from the anterior pituitary which in turn causes testosterone released from testes. Circulating levels of testosterone feedback to the anterior pituitary to regulate LH output
?5) A mechanism by which drug could not on the anterior pituitary to lower the testosterone level is the continous administration of a GnRH agonist. This would initially lead to transient increase in LH and testosterone levels which would feedback to anterior pituitary to reduce LH output.