Renal Control Of Acid-base Balance

Question 1

Is there a higher [H+] intracellularly or extracellularly?

Answer 1

Intracellularly

Question 2

What is the pKa for carbonic acid?

Answer 2

6.1

Question 3

Where is bicarbonate primarily reabsorbed?

Answer 3

In the PCT

Question 4

Where does the NKCC transporter reside in the nephron?

Answer 4

In the TAL

Question 5

How does ammonia get excreted?

Answer 5

It exists as ammonium in the tubular fluid and gets secreted into the interstitium by the NKCC transporter in place of K+

In the interstitium it gets converted into ammonia, gets pumped into the collecting duct and excreted

Question 6

If there is acidic blood, what do the alpha intercalated cells do?

Answer 6

They secrete H+ and reabsorb HCO3-

Question 7

If there is alkalotic blood, what do the beta-intercalated cells do?

Answer 7

They reabsorb H+ and secrete HCO3-

Question 8

What is a titratable acid?

Answer 8

Salts that are primarily phosphate and have a pKa are lower than 7.4

Account for ~1/3 of net acid excretion

Question 9

What is net acid excretion?

Answer 9

It must be equal to nonvolatile acid production each day in order to maintain acid-base balance

Question 10

What accounts for 2/3 of NAE?

Answer 10

Ammonium

Question 11

What is normal anion gap?

Answer 11

8-16 mEq/L

Question 12

What are causes of high anion gap metabolic acidosis?

Answer 12

M ethanol
U remia
D KA
P araldehyde
I soniazid (treats TB)
L actic acidosis
E tOH

Question 13

What are causes of non-anion gap acidosis?

Answer 13

H yperalimentation
A cetazolamide 
R enal tubular acidosis
D iarrhea
U retero-pelvic shunt
P ost-hypocapnia
S pironolactone

Question 14

How do you diagnose renal tubular acidosis?

Answer 14

Acidemia + normal anion gap + normal serum creatinine+ no diarrhea

Question 15

What is the most common type of RTA?

Answer 15

Type 4

Question 16

Where is the location of defect for RTA type 1?

Answer 16

Distal tubules

Question 17

Where is the location of defect for RTA type 2?

Answer 17

Proximal tubules

Question 18

Where is the location of defect for RTA type 4?

Answer 18

Adrenal gland

Question 19

Which RTA types have hypokalemia?

Answer 19

Type 1 and type 2

Question 20

What is the pathophysiology of RTA type 1?

Answer 20

H+ secretion by alpha-intercalated cells is impaired

Question 21

What is the pathophysiology of RTA type 2?

Answer 21

Failed HCO3- reabsorption from the urine by the proximal tubular cells

Question 22

What is the pathophysiology of RTA type 4?

Answer 22

Low aldosterone or a failure to respond to it

Question 23

Why is RTA type 4 the most common form?

Answer 23

It is most common because ACE inhibitors block RAAS and if it is blocking aldosterone, it would result in this presentation

Question 24

What are some causes of metabolic alkalosis?

Answer 24

C ontraction
L icorice 
E ndo: (Conn, Cushing, Bartter)
V omiting
E xcess alkali 
R efeeding alkalosis

P ost-hypercapnia

Question 25

Causes of respiratory acidosis?

Answer 25

C NS depression
A irway obstruction
N euromuscular disorders
S evere pneumonia, embolism, edema

Question 26

Causes of respiratory alkalosis

Answer 26

C NS disease
H ypoxia
A nxiety
M echanical ventilators
P rogesterone
S alicylates/sepsis