Distal Renal Tubular Disorders - Ault

Question 1

What are the targets of the following drugs?

Acetazolamide

Furosemide, bumetanide, ethacrynic acid

Thiazide

Amiloride, tramterene

Spironolactone, eplerenone

Answer 1

Acetazolamide - carbonic anhydrase

Furosemide, bumetanide, ethacrynic acid - Na-K-2Cl

Thiazide - NaCl

Amiloride, tramterene - ENaC

Spironolactone, eplerenone - Mineralocorticoid receptor

Question 2

What are the mutations present in Bartter syndrome?

Answer 2

N-K-2Cl

ROMK

Cl- channel (CLCNKA, CLCNKB)

Barttin (Cl channel)

Question 3

What are the mutations present in Gitelman Syndrome?

Answer 3

Thiazide-sensitive NaCl channel

Question 4

What are the mutations in Liddle Syndrome?

Answer 4

Gain of function in ENaC

Question 5

What is TTKG and what is the equation?

Answer 5

Transtubular Potassium Gradient

TTKG = (UK * Posm) / (PK * Uosm)

Question 6

What are expected values of the TTKG in hypokalemia and hyperkalemia?

Answer 6

Hypokalemia < 2

Hyperkalemia > 8

Question 7

What is the effect of hyperaldosteronism on potassium?

Answer 7

Hypokalemia

Question 8

What are causes of hyperaldosteronism?

Answer 8

Primary (tumors)

Dehydration (pyloric stenosis)

Sodium-wasting disorders (Bartter-Gitelman)

Glucocorticoid-remediable hyperaldosteronism (GRA)

Apparent mineralocorticoid excess (AME)

Question 9

What is the cause of glucocorticoid-remediable hyperaldosteronism (GRA)?

Answer 9

Recombination protducing hybrid molecule that makes ldosterone in response to stress

Question 10

What are the effects of glucocorticoid-remediable hyperaldosteronism (GRA)?

Answer 10

Low renin hypertension

Hypokalemia

Question 11

What is the cause of apparent mineralocorticoid excess (AME)?

Answer 11

Increased renal cortisol

Question 12

What are the effects of apparent mineralocorticoid excess (AME)?

Question 13

What is the effect of hypoaldosteronism and pseudohypoaldosteronism on potassium?

Answer 13

Hyperkalemia

Question 14

What are the causes of hypoaldosteronism?

Answer 14

Congenital adrenal hypoplasia

Congenital adrenal hyperplasia

Autoimmune

Question 15

What are the causes of pseudohypoaldosteronism?

Answer 15

PHA Type I

PHA Type II

Tubular injury (obstructive uropathy)

Question 16

What are symptoms of PHA Type I?

Answer 16

Hyperkalemia

Hyponatremia

Hypotension

Question 17

What are the causes of PHA Type I?

Answer 17

Mutation in mineralocorticoid receptor

Loss of function of ENaC

Question 18

What is the treatment of PHA Type I?

Answer 18

Sodium supplements

High fluid intake

K-binding resin

Question 19

What are symptoms of PHA Type II?

Answer 19

Hyperkalemia

Hyperchloremic metabolic acidosis

Hypertension

“Gordon syndrome”

Question 20

What are the causes of PHA Type II?

Answer 20

Mutations in NaCl cotransporter

Question 21

What is the treatment of PHA Type II?

Answer 21

Thiazide diuretics

Question 22

What should you check first in metabolic acidosis?

Answer 22

Plama anion gap

Na - (Cl + CO2)

Question 23

What causes elevated anion gap acidosis?

Answer 23

Ketoacidosis

Lactic acidosis

Metabolic errors

Poisons (ethylene glycol)

Question 24

What causes normal anion gap acidosis (hyperchloremic metabolic acidosis)?

Answer 24

GI losses of bicarbonate

Exogenous chloride

Renal tubular acidosis

Question 25

What principle does TTKG measure?

Answer 25

Aldosterone response in hypo/hyper kalemia

Question 26

What is the anion gap in RTA?

Answer 26

Normal anion gap acidosis

Question 27

What are the types of RTA?

Answer 27

Type II (proximal) - associated with Fanconi Type I (classical distal) - very rare Type IV (hyperkalemic) - syndrome of aldosterone deficiency

Question 28

What are the tests for RTA?

Answer 28

Fractional excretion of bicarbonate Urine pH Urine anion gap U-B PCO2

Question 29

What are the fractional excretions of bicarbonate in each type of RTA?

Answer 29

Type I (classical distal) - \<5% Type II (proximal) - \>10-15% Type IV (hyperkalemic) - \<5-10%

Question 30

What is the urine pH in each type of RTA?

Answer 30

Type I (classical distal) - \>5.5 Type II (proximal) - \<5.5 Type IV (hyperkalemic) - either

Question 31

What is the equation for urine anion gap?

Answer 31

Na + K - Cl

Question 32

What is the value of the urine anion gap in diarrhea?

Answer 32

Negative

Question 33

What is the value of the urine anion gap in RTA?

Answer 33

Positive

Question 34

What is the U-B PCO2?

Answer 34

Measure of secreted CO2 following a HCO3 load

Question 35

What are the results of a U-B PCO2 in each type of RTA?

Answer 35

Type I (classical distal) - \<10-15 Type II (proximal) - 10-15 Type IV (hyperkalemia) - \<10-15

Question 36

What is a distinguishing feature of Type II (proximal) RTA?

Answer 36

Fanconi syndrome

Question 37

What is a distinguishing feature of Type IV (hyperkalemic) RTA?

Answer 37

High plasma K

Question 38

What causes RTA type IV?

Answer 38

Mineralocorticoid deficiency / resistance Renal tubular dysfunction