RTA type II, well where am I? Proximal convoluted
tubule. Bottom line is inside of the picture,
luminal membrane, what's in that lumen? Urine.
Epithelial cell, what kind? PCT and there is
my blood. Here you see the red X represents
either a patient genetically was missing carbonic
anhydrase, you can pharmceutically induce
this by giving which drug? Something like
acetazolamide to inhibit that carbonic anhydrase.
Or what if you had a condition such as Fanconi
syndrome that is causing complete destruction
of the proximal convoluted tubule and in any
of the cases that I just gave you in terms
of numerous etiologies, what have you done
to renal threshold for reclaiming bicarb?
You have decreased it. When doing so, out
goes the bicarb, you end up having a pH in
your blood that is decreased. Welcome to RTA
type II. Please do not miss this. What I wish
to bring to your attention, once you diagnosed
your patient metabolic acidosis, this next
step that you have to take clinically every
single time is called anion gap. Anion gap means
what? Keep it simple. Cations minus the anions.
The only cation that you will be taking into
consideration clinically is sodium, why? 135
to 145 is normal. Calcium is the other cation, but it's only
3.5 to 5, so let that go. Anions, there is two of them.
So from your cation, sodium, you will subtract
your anions. Those include your chloride,
which is between 95 to 105 and every bicarb
between 22 to 26. This is something once again
you have doubt with in acid-base physiology.
Make sure you know about anion gap, when is the
only time that you will be using this clinically?
Metabolic acidosis, right? And here RTA type 2, there is
a normal anion gap. All renal tubular acidosis,
normal clinically is called nonanion
gap metabolic acidosis. What is normal anion
gap? Between 8 and 12. Don't worry. This is
our first time in which we are dealing with anion
gap. There is plenty of more places where
we will do anion gaps. If you miss this, first
time round, go back and repeat or bear with
me here because we will see this over and
over again. Type II, impaired reabsorption of
bicarb, outer it goes. Welcome to RTA type II.
Or with type 2, there might be impaired secretion
of your hydrogen. Remember when you say renal
tubular acidosis, be careful, what is that
acidosis referring to? The acidosis is referring
to the blood. Is that clear? That is your
pathology. This is not aciduria.
This is renal tubular acidosis so
this would be of the blood. Or like we said, effective
or deficiency of carbonic anhydrase. Large
amounts of bicarb are gone and generalized
PCT dysfunction may also result in large loss
of bicarb such as Fanconi. Discussed this
plenty. Inhibitors and other conditions causing
damage to the PCT. Myeloma, we will head over
and over again. Drugs that are nephrotoxic
and cystinosis, which is rare, but could be an inherent
cause of damage to the proximal convoluted tubule.