peds in review Flashcards
How does the body maintain acid base balance
Excrete hydrogen ions (H+) or resorb Bicarb (HCo3-)
Where in the body does H+ get excreted?
And how does the body prevent it from getting reabsorbed?
In the distal convoluted tubule and the collecting duct
It combines with ammonia to form ammonium and ammonium chloride cannot be reabsorbed, because ammonium is positively charged it looks to combine with someone negatively charged and that is chloride.
How does distal RTA present and why?
problem with excreting H+ in the distal tubule.
Presents with an inappropriately positive urine anion gap. If the blood is acidic, you should had a lot of chloride because chloride combines with ammonium.
It can present at any time of life becuase it can be caused by medications (amphotericin, ifosfamide, lithium), infections, and congenital malformations.
Urine anion gap calculation
UAG= [urine Na+]+ [urine K+] - [urine chloride-]
Where does bicarb get reabsorbed?
bicarb is filtered by the glomerulus and reabsorbed by the proximal convoluted tubule.
how does proximal RTA present?
The proximal tubule normally resorbs almost all filtered bicarb.
For someone with proximal RTA that serves fairly true too because they’ve had a long time of just absorbing as much bicarb as they can so the serum bicarb has decreased in time.
So to access how the body handles bicarb you have to give them a load. (Usually 2-4 mEq/kg/day) . and then you will test the fractional excretion of bicarb. If it is >5% you likely have proximal RTA.
What is type IV RTA
hyperkalemic RTA, multi-effect, but basically have a problem with aldosterone production or receptor sensitivity, Aldosterone has a direct stimulating effect on the cells that increase H+ excretion
