doyoudig
Forum Guru
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not quite understanding it yet
1. in type II - unable to absorb HCO3 in the prox tubule so you are loosing HCO3 into the Urine which makes it basic, but why ph < 5.4??
2. then u give IV NaHCO3 and what should that do exactly???
3. In type I when u give acid, the kideny is still not able to excrete it, hence urine stays basic > 5.4??
4. also why do you observe Hypokalemia in both types, what the mechanism?
culd u pls clarify those pts
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| Jesussaves
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In type II the defect is reabsorption of HCO3 in PT so the initial urine pH is basic but remember the distal tubule is intact so once the HCO3 level comes in the range of absorption of the distal tubule that is after a lot of HCO3 is lost the distal tubule absorbs it and now the urine is acidic.Try reading it in Kaplan again
Guess you will understand it better
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| Jesussaves
Forum Junior
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about hypokalemia
In type I it is due to renal salt wasting
In type II it is that increased delivery of HCO3 also increases K+ secretion
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| doyoudig
Forum Guru
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thank You
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| prathapdoctor
Forum Elite
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, except in proximal convoluted tubule, bicarbonate is not going to be absorbed any where else in the kidney.
in type2 RTA, initally urine will be basic because of impaired absorbtion of HCO3- by PCT, but once the plasma level of bicarbonate reaches certain level(lower than normal), all the filtered bicarbonate will be reabsorbed in PCT,because that amount is going to be very low when compared to the filtered amount when its conc is 26 meg per liter.so there is decreased bicarbonate in serum leading to metabolic acidosis.
so because of acidosis, the kidney tries to compensate by secreting H+ which leads to acidic urine.
Hope you got my point.
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