new_n_lost
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I wanted to start a topic where we could mention the hormones which Decrease with Age
Overall, some hormones are decreased, some unchanged and some increased with age.
Hormones that are usually decreased include:
Aldosterone
Renin
Calcitonin
Growth hormone
In women, estrogen and prolactin levels usually decrease.
Hormones that remain unchanged or only slightly decreased include:
Thyroid hormones T3 and T4
Cortisol
Insulin
25-hydroxyvitamin D
Testosterone levels usually decrease as men age.
Hormones that increase include:
Follicle-stimulating hormone (FSH)
Leutinizing hormone (LH)
Norepinephrine
Epinephrine
Parathyroid hormone
Edited by new_n_lost on 03/02/07 - 08:57 PM
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| new_n_lost
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The target organ for mineralocorticoid activity (kidney), however, becomes less responsive as age progresses and sodium losses become more fixed as age progresses. Thus, the effect of increasing mineralocorticoid activity is apparently blunted by end organ resistance. Generally, the response to antidiuretic hormones appears to be better preserved. Individuals can clear free water better than they can conserve sodium. Therefore, when stressed, most older individuals become hyponatremic
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| new_n_lost
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Although total serum renin concentration remains stable with age, there is an age-dependent decline in active renin concentration. This is responsible for a blunted renin response to postural changes, and is one of the mechanisms postulated for the frequency of postural hypotension in the elderly.
Because of the decreased GFR, blunted renin-aldosterone axis, and decreased tubular mass, the elderly may have less ability to protect against hyperkalemia in the face of increased potassium loads. Systematic studies in this area, however, still need to be done.
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| Luckyall
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 Good job !
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| paganini
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Could you tell where you found that info?
I agree with you in that renin synthesis decreases with age, but I don't think it woould affect postural changes, the reflex mechanism is via the baroreceptors in the carotids not in th kidney. Although the kidney contribute to this response they are not the main response and the body can respond well to postural changes. The kidneys participate in the baroreceptor response via increased sympathetic activity that was caused by a decreased firing rate of the arterial baroreceptors, this causes the kidney to retain fluid, via B1 activation of renin-angio-ald.... But this is a long term response. The immediate response occurs in the heart and arteries, via increased sympathetic activity and decreased parasympathetic activity.
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| new_n_lost
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Its Postualated Mechanism (still under- working) I do agree with u on the mechanism though.
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| SmokyWaters
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I agreee with paganini because the most appropriate answer to that seems to be the same...the rare notions that everybody cud make is very easy ...but we are talkin about USMLEs here..right??  anyway..nice discussion goin on...
btw...is postural hypotension a consequence of chronic depletion of body fluids??? cuz postural hypotension is due to the brisk reflexes..right? I just got confused after reading all this above...provided that if ITS CORRECT
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| new_n_lost
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The Above Info is Correct Last time i chked from Different Sources but i open to other sources brought to light by u guys n thats the reason iu started this discussion Will be glad if u could add more to this.
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| SmokyWaters
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| dreaming doctor
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really good
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| paganini
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Wel I think that postural hypotension is usually due to pooling of the blood by gravity into the legs, which decreases venous return and therefore cardiac output, this could decreased the blood going into the brain a this might result in syncope,this is a very long topic and I do not want to create a monologue but I am going to start a discussion in this so please post any other ideas that can complete the mechanisms I am mentioning. Now, we all have a mechanism to avoid the postural changes in blood pressure, most of all think immediately in arteriolar resistance, this is true and this actually help to prevent pooling of the blood but not in the venous compartmet, this mainly affects the ARTERIAL compartment, so this is not enough and therefore not the only mechanism, but you can notice that is an important mechanism because as a side effect drugs that are used to treat hypertension by decreaseing TPR may cause postural hypotension. The other very important mechanism and that is not so obvoius and is the one that I think might contribute to a postural hypotension in the elderlies is the function of the muscle pump(ALL THE LOWER EXTREMITIES MUSCLES), this prevents the VENOUS pooling in the lower extremities and this can explain why people do not get edema in the legs if they are in a vertical position for an hour or 2. This prevents the venous pooling and also prevents an increase in hydrostatic pressure that would cause movement of fluid to the interstitium and the edema, hydrostatic pressure in fact increases bu not so much so that the lymphatics can remove any fluid that filters. You can also notice the importance of this mechanism in preventing postural hypotension because a person can lose conciousness after 20 min if that person is stand up without moving the legs or the muscles of the lower extremities. In my country that happened recently to a General that was behind the President when the President of my country (sorry I prefer to be anonymous here)was giving a very long speech, the General faint after 30 minutes of speech, I assume that the hot weather inside the room (we have a hot weather) contributed to that because the high temperature would cause vasodilation and increased flow in the skin and this would decrease TPR. It was funny to see this on TV because the President got scared and also some people later were saying that maybe the President ate something, maaybe (eggs and beans) this morning and then released a gas to the face of the General, lol hahaha... Well returning to the discussion and after saying all this I think this could also explain why elderlies are more prone to postural hypotension, I think that a reduced muscle mass + a decrease sensing of the baroreceptors affect the normal control to changes in posture. The kidneys would not contribute to this immediate response as I said before.
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