Renal tubular acidosis RTA

Question 1

distal RTA is also known as

Answer 1

type 1

Question 2

distal RTA (type 1) is from

Answer 2

autoimmune diseases (Sjogren’s, RA),

liver cirrhosis

drugs (amphotericin B, lithium),

toxin ingestion (toluene)

Question 3

toluene solvent inhalation can result in

Answer 3

type 1 (Distal) RTA with congitive impairment and flaccid weakness and absent DTR

Question 4

Toluene solvent inhalation pathophysiology

Answer 4

toluene is inhaled and converted into liver by hippuric acid that creates a high anion gap metabolic acidosis early stages.

but hippuric acid is rapidly excreted by the kidneys along with sodium and potassium.

This limits renal ammonium production and eventually causes distal RTA (type 1).

Muscle weakness is from low K and low level rhabdomyolysis and hypophosphatemia

also see altered mental status

Question 5

Treatment of toluene solvent inhalation

Answer 5

supportive care with IVFs and electrolyte repletion

Question 6

Defect in RTA type 1 (distal)

Answer 6

inability to have H+ (and Cl) secretion in distal tubule so unable to acidify urine.

Results in urine pH in being >5.5

see hypokalemia since H is being retained and K is being pushed out

Question 7

Defect in type 2 proximal RTA

Answer 7

bicarbonate is NOT reabsorbed in proximal convoluted tubule.

See urine pH is <5.5 and so we see hypokalemia.

Question 8

Defect in Type 4 RTA for (distal)

Answer 8

inadequate aldosterone response impairs distal Na resorption/K secretion.

Most common RTA

See urine pH<5.5

Question 9

proximal RTA is

Answer 9

Type 2 RTA = defect in bicarbonate reabsorption

see hypokalemia

occurs in the proximal tubule.

Question 10

hyperkalemic RTA

Answer 10

type 4 - low or no spironolactone

Question 11

RTA type 4

Answer 11

impaired aldosterone at tubular level so see hyperkalemia and seen with DM2

Question 13

distal RTA can result in

Answer 13

non anion gap metabolic acidosis and marked hypokalemia and hypophosphatemia with inappropriately high urine pH.

Question 14

distal RTA is also known as

Answer 14

Type 1

Question 15

RTA 1

Classical type

Answer 15

Tubules are not secreting chloride or cannot excrete H+

so this causes chloride to go up in serum

Because the chloride is not in PH the urine is alkaline. so the bicarb drop in the serum. so the chloride is high the serum pH becomes acidic.

seen in Sjogrens and SLE Amphotericin B and stones and obstruction with stones. When urine is more alkaline it can see calcium phosphate stones more.

Question 16

Proximal RTA

RTA type 2

Answer 16

primary defect is reabsorption of bicarb HCO2

so see loss of serum K and loss of serum bicarbonate (and see serum pH drop because deficit in bicarbonate).

Urine pH is variable:

<5.5 when Cl is excreted and urine Cl helps to keep it acidic

>5.5 when not in steady state and not as much CL is excreted in urine so the urine pH is higher.

no kidney stones

-seen in falconi syndrome, multiple myeloma, acetazolamide, zonisamide, topiramate, osteomalacia

Question 17

RTA 4 is with

Answer 17

defect: H and K excretion into urine.
- since no H is being excreted out will not see Cl- excreted into urine so urine pH> 5.5 (alkaline)

causes a non anion gap metabolic acidosis due to loss of aldosterone. Distal tubule Na reabsorption is controlled by aldosterone and linked with acid secretion. If there’s low aldosterone then the renal tubule has sodium wasting in urine and hydrogen retention in the serum.

seen with low hypoaldosteronism (addison’s dx) and DM2, renal insufficiency, spironolactone/eplerenone, trimethoprim

Question 18

why do you see a non anion gap metabolic acidosis in ureterosigmoidostomy?

Answer 18

ureterosigmoidostomy - secretion of urine into bowel so creating an artifical diarrhea

same process of diarrhea -losing bicarbonate through lower GI tract .

Question 19

what are the effects of RTA 2?

Answer 19

can cause lose glucose, uric acid, phosphate, calcium and potassium and protein.

Urinary losses of phosphate and calcium increase risk for osteomalacia and osteopenia.

Can have generalized CKD.

Question 20

All RTAs cause this metabolic disturbance?

Answer 20

non anion gap metabolic acidosis

Question 21

Sjogren’s is associated with

Answer 21

RTA type 1 distal

Question 22

hypoaldosteronism is associated with

Answer 22

RTA type 4 with urine pH<5.5 and hyperkalemia and positive urine anion gap.

Question 23

aldosterone resistance is associated with

Answer 23

RTA type 4

urinary obstruction

sickle cell dx

medullary cystic kidney dx

kidney transplant rejection

Question 24

Drug induced type 4 RTA is with

Answer 24

drugs that reduce aldosterone production:

ACEi, ARB, heparin, NSAIDs.

See positive urine anion gap.

• reduced excretion of acid in the form of ammonium and chloride but has urine pH<5.5