mani
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a pt is diabetic and is careless about diabetic control. his slood glucose is raised. can increased increased glucose lead to increased GFR? if yes how??
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| Sakaki-
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In the initial phase of diabetic nephropathy, the GFR is indeed raised. (As for the mechanism, I'm not sure).
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| mash
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increased gfr in early stages is due to efferent arteriolar hyaline arteriosclerosis which increses glomerular filtration pressure.
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| peekay
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I WONDER IF IT HAS SOMETHING TO DO WITH INCREASED OSMOLAR CONCENTRATION AS WELL.AND WHY NOT AFFERENT ARTERIOL CONSTRICTION
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| mash
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afferent arteriolar constriction wud decrease gfr.
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| peekay
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what i was saying is this that if there is efferent involved than why not afferent is affected.
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| medical1
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I WONDER WEATHER THERE IS NO CHANGE IN gFR??
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| mani
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man, u gotta do q bank. so dont worry. u will get that!!
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| suvi21
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osmotic diuresis
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| rubyduby
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is it becuz of increse glucose overload?
efrent constriction always incerese GFR and afferent decreses GFR dats i know, but i still agree wid one of my feloow here who asked why in diabetics only eferents invloed why not afrenet, i think it shud invlve both arterioles evenly.. can any one pls expaling this answer well. becuz renal questions are most tetsed in usmle
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| rubyduby
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or glucose is freely filtered? and its overload is very high...if they mention effernt and afferent aretiroles is this the possiblty i mentioned?
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| rubyduby
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or glucose is freely filtered? and its overload is very high...if they DONT mention effernt and afferent aretiroles is this the possiblty i mentioned?
sorry in lprev. post i forgot to write wont...
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| mdwannabe
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Osmotic Diuresis... more glucose spills (above 200 mg/dL will saturate transporters in PCT) more water remains in tubules...more comes out.
Sorry if I am reapeating... i did not read all the responces.
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| almina
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so, if more water remains in tubules(because of glucose) - the volume of urine increases, and less will be reabsorbed. Does nost has to do with GFR, does it?
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| Sakaki-
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I agree with almina; an osmotic diuresis does not increase the GFR.
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| Renegade
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I noticed this old post, I don't think the true mechanism the causes increase in GFR in diabetes has been explained. But before I spoil, how about 2 tips?
1-Osmotic Diuresis has nothing to do with it, since it only works inside the tubules, by drawing water, not at the vessels.
2-The true mechanism also is responsible for a max 20% increase in GFR after a protein-rich meal.
The mechanism: Hyaline arteriosclerosis indeed increases filtration pressure, but that only happens later on. However, as soon as your blood glucosis rises or after you eat a protein-rich meal, more of these molecules will, as expected, be present in glomerular filtrate. Once it reaches DCT, the usual mechanisms will absorb more glucosis/aminoacids... how? By absorbing Na as well. Once the fluid reaches the macula densa, [Na] is a bit low, therefore :arrow: renin :arrow: angiotensin :arrow: efferent arterioles constriction :arrow: increased GFR. This would be an important mechanism for polyuria in DM (along with diuretic osmosis), if it weren't for the Donnan mechanism in severe efferent arterioles contraction.
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