Of course, you can have a metabolic acidosis
without an elevated plasma ion gap.
And some of the best examples
of those happen in the kidney.
These are Renal Tubular Acidosis of which
there are three types that we need discuss.
Type 1, Type 2 and Type 4.
To compare this, the best thing to do is
to think about where does the problem lie.
It just so happens that Type 1 Renal Tubular Acidosis
is a problem with acid secretion.
While Type 2 Renal Tubular Acidosis
is impaired by carbonate secretion.
And Type 4 is also
impaired acid secretion.
If you can keep this as straight as possible,
you’re hopefully be able to better diagnose
what your Renal Tubular Acidosis might be.
So, 1 and 4 impaired acid secretion,
type 2 bicarbonate secretion.
The disorders that are associated
with these can be numerous.
Many of them involve some genetic disorder.
Rheumatoid arthritis is often times associated
with Type 1 Renal Tubular Acidosis.
Some drugs such as carbonic anhydrase inhibitors
are associated with Type 2 Renal Tubular Acidosis.
And for Type 3 Renal Tubular Acidosis,
Addison’s disease is a great example
of trying to tie those together to a clinical condition.
All of them will respond with a
Renal Tubular Acidosis, is metabolic acidosis.
You noticed we didn’t mentioned Type 3, right?
You won’t see it.
To summarize, the acid base disturbances
we can utilize this type of a chart.
A respiratory acidosis always involves
a decrease in pH, a small increase in bicarb
and a large increase in carbon dioxide.
A respiratory alkalosis is an increase in pH,
a small decrease in bicarb
and a large decrease in C02.
Metabolic acidosis is a decrease in pH,
a large change in bicarb
with no change in CO2.
A metabolic alkalosis is an increase in pH,
a large increase in bicarb
with really no change in PCO2.
The other thing to keep in mind
with summarizing this acid base disorders,
you have an initial disorder and then,
you might have a response to it.
If you think about the diagrams
it will always help you try to predict
what the compensation is gonna be.
So, you have your four primary disorders
that we’ve just covered in the table.
You have a respiratory acidosis, respiratory alkalosis,
metabolic acidosis, metabolic alkalosis.
How are you going to try to fix this problems?
Well, a partial fix usually involves
the opposite system.
So, if you have a respiratory acidosis,
you try to fix it with a metabolic alkalosis.
If you have a metabolic acidosis,
you try to fix it with a respiratory alkalosis.
If you have a metabolic alkalosis,
you try to fix it with a respiratory acidosis.
And finally, if you have a respiratory alkalosis,
you try to fix it with a metabolic acidosis.
Partial compensation, means you are
moving your pH back towards normal.
but you may not have reached normal yet.
Once you reached normal,
it’s called perfectly compensated.
I would like to say that we usually become
perfectly compensated but life is not perfect.
Usually, you partially compensate and eventually
are trying to move back to normal ranges
and often times you never get there
but you’re trying to do that process.
The last type of disorder that I’m just going
to bring up as a problem that happens
is if the disorders are mixed.
Mixed or compound disturbances mean
that you have more than one problem.
And these are very serious conditions.
A type when you could have a respiratory acidosis
and a metabolic acidosis at the same time.
Those are very hard to fix because
both systems are moving pH in the same way.
Just like if you had a metabolic alkalosis
with a respiratory alkalosis at the same time.
Again, very hard to fix because
you have multiple compound problems.