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Renal II Quiz II > Acquired and Congenital Tubular Function Defects > Flashcards

Acquired and Congenital Tubular Function Defects Flashcards

1
Q

What are the main urine output findings in Barter Syndrome?

A

Symptoms of a loop diuretic (furosemide)

Elevated plasma renin and aldosterone

Hypokalemia:

  • hypomagnesmia
  • hypochloremia —> metabolic alkalosis
  • Hypoglycemia

Isotonic urine

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2
Q

What type of inheritance is associated with Gitelman syndrome? (22)

A

AR

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3
Q

What is the typical onset of Gitelman Syndrome? (22)

A

Late childhood or adulthood (AR); life-long

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4
Q

What type of diuretic does Gitelman Syndrome mimic? What are the clinical findings as a result of this mimicry?

A

Mimics thiazide diuretics (Gitelman Syndrome will not respond to thiazide diuretics)

Hypercalcemia

Hypomagnesemia (may be severe)

dilute or concentrated urine

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5
Q

How do we treat Gitelman Syndrome? What treatment should be avoided? (24)

A

Life-long Supplementation:

  • Sodium (most important) - want to avoid triggering aldosterone
  • potassium - want to achieve stable hypokalemia
  • magnesium - want to achieve borderline hypomagnesemia

NSAIDS are infective (defect in distal convoluted tubule after macula densa)

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6
Q

Mutation changes in eNaC channel (collecting duct) resulting in incorrect degradation by ubiquitin proteasome leading to increased Na+ reabsorption

A

Liddle syndrome (Pseudoaldosteronism)

(very rare)

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7
Q

Liddle Syndrome is defined by the prescence of ENaC channels that do not degrade by ubiquitin proteasome and are therefore always present. What complications do we see as the result?

A

increased sodium reabsorption:

  • low plasma renin —> low aldosterone
  • severe HTN
  • metabolic alkalosis

potassium loss (hypokalemia)

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8
Q

Renal loss of HCO3- due to failure to reabsorb filtered HCO3- with hyperchloremia

A

Type 2 RTA (Renal Tubular Acidosis)

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9
Q

Distal nephron, reduction in excreted H+ as titratable acid and NH4+ with a decreased ability to acidify urine

A

Type 1 RTA (Renal Tubular Acidosis)

impairment of α-intercalated cells resulting in no H+ secretion —> now you can’t make new bicarbonate (using NH3+) —> severe acidosis

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10
Q

Distal nephron, type of renal tubular Acidosis occurring as a result of hypoaldosteronism with lowered excretion of NH4+ due to inhibition of NH3 synthesis as a result of hyperkalemia.

AKA you don’t have enough ammonia to act as a buffer

A

Type 4 RTA (Renal Tubular Acidosis)

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11
Q

What feature is consistent with all RTA types?

A

normal anion gap

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12
Q

What is the location, acid/base status, and potassium level in RTA type 1?

A

Distal tubules

Severe acidosis (NAG)

Hypokalemia

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13
Q

What is the location, acid/base status, and potassium level in RTA type 2? (31)

A

Proximal tubule

Severe acidosis (less severe than type 1)

Hypokalemia

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14
Q

What is the location, acid/base status, and potassium level in RTA type 4? (31)

A

adrenal (proximal tubule not putting enough ammonia (H+ acceptor) in the tubule)

mild acidosis (NAG)

Hyperkalemia

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15
Q

A general defect of the proximal tubule where there is reduced reabsorption of sodium, glucose, phosphate, amino acids, and bicarbonate

A

Fanconi Syndrome

These substances show in the urine

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16
Q

What are the clinical features of Franconi Syndrome?

A
  1. polyuria and polydipsia
  2. Phosphaturia, glycosuria, and proteinuria
  3. hypokalemia, hypochloremia (due to HCO3- loss)
  4. growth failure (bones)
  5. type 2 renal tubular acidosis
17
Q

One of the clinical features of Franconi Syndrome is growth failure in reference to bone health. Describe how this feature presents in children and adults

A

Children: rickets

Adults: osteomalacia

18
Q

What are the important inherited, acquired, and exogenous factors that increase the risk of Fanconi’s Syndrome?

A

Cystinosis (AR)

Tyrosinemia type I (AR)

Wilson’s disease (AR)

Nephrotic Syndrome

multiple mylenoma (Bence Jones Proteins)

Heavy metals (mercury)

19
Q

What medications are exogenous factors that can cause Franconi Syndrome due to nephrotoxicity?

A
  1. aminoglycosides (gentamicin)
  2. cisplatin
  3. valproate
  4. gliflozins
20
Q

What is the treatment for Franconi Syndrome?

A

General rule: replace the substances that are wasted:

  • Use citrate instead of bicarbonate (HCO3-) - broken down to bicarb in metabolic processes and the bicarb isn’t lost (because it’s not in the kidney)
21
Q

What is the associated gene mutation and defect in Classic Bartter’s Syndrome (type 3)?

A

CLCNKB channel (Chloride channel)

22
Q

What is the clinical presentation of Bartter Syndrome?

A
  • No noticeable symptoms until school age (kindergarten age)
  • vomiting
  • growth retardation
  • symptoms similar to loop diuretics (furosemide)
23
Q

What is the treatment for Bartter Syndrome?

A
  • dietary sodium and potassium intake
  • potassium-sparing diuretics
  • NSAIDs (inhibition of PGE2 from MD)
24
Q

Why are NSAIDs beneficial to a Bartter Syndrome patient?

A

Because Bartter Syndrome is a defect of the thick ascending limb of Henle high amounts of PGE2 are generated because the defect is prior to the macula densa

NSAIDs can block the high amounts of PGE2 generated

25
Q

In terms of treatment, what is a big differentiator from how Bartter Syndrome is treated vs how Gittelmans is treated?

A

Gittelmans cannot be treated with NSAIDs

26
Q

Where in the nephron is Gitelman Syndrome associated with?

A

distal convoluted tubule (NaCl cotransporter)

27
Q

Why in Gitelman Syndrome do we use supplementation to only achieve a stable hypokalemia and borderline hypomagnesemia?

A

Supplementation causes GI side effects

28
Q

What are the main differentiators between Bartters Syndrome and Gitelman Syndrome?

A

Bartter Syndrome:

  • Produces isotonic urine
  • hypocalemia/hypercalciuria
  • give loop diuretic, if they don’t respond = + for Bartter

Gitelman Syndrome:

  • produces dilute or concentrated urine
  • more benign than Bartter Syndrome
  • hypercalemia/hypocalciuria
  • give thiazide, if they don’t respond = + for Gitelman
29
Q

How do we treat Liddle Syndrome?

A

low sodium diet

potassium-sparing diuretics

30
Q

What is the most common RTA type?

A

RTA Type 4 (Hyperkalemic)

  • lack of aldosterone or failure to respond
  • Proximal tubules not putting enough ammonia in the tubule to act as a buffer (H+ acceptor)
31
Q

What are the common secondary causes of RTA Type 1 (Classic)?

A

Autoimmune disorders (SLE, RA, Sjogrens)

32
Q

What are the common secondary causes of RTA Type 2 (proximal)?

A

In children: Franconi Syndrome

In adults:

  • multiple myeloma (bence jones proteins)
  • drugs (Aminoglycosides: gentamicin, tenofovir)
33
Q

Which type of Renal Tubular Acidosis is the only type to produce Hyperkalemia? What causes this?

A

RTA Type 4

caused by either low aldosterone or lack of response to aldosterone

RTA Type 4 think: proximal tubule not putting enough ammonia into tubule to act as a H+ acceptor

34
Q

What is the defect in Type 1 RTA? What cascading effect does this have?

A

impairment of α-intercalated cells resulting in no H+ secretion —> now you can’t make new bicarbonate —> resulting acidosis

35
Q

How do we treat RTA Type 1 (classic)?

A

Hypokalemia is major consequence (weakness, irregular rhythm, paralysis):

  • correct low potassium
  • correct salt depletion

due to acidosis:

  • give sodium bicarbonate or sodium citrate (1-2 mEq/kg/day)
36
Q

What is the defect in RTA Type 2?

A

Fanconi Syndrome: Bicarbonate is not being reabsorbed in proximal tubule

37
Q

How do we treat RTA Type 2?

A

Treating directly with bicarbonate is useless because the problem is an inability to reabsorb bicarbonate, additional bicarbonate will simply be excreted

  • Administer Potassium Citrate (10 - 15 mEq/kg/day) - large dose
  • Vitamin D to prevent bone issues
  • correct low potassium
38
Q

Describe the physiology behind RTA Type 4?

A

With low aldosterone or lack of response to aldosterone —> high K+ —> low NH3+ Synthesis (proximal tubule)

With low amounts of NH3+ in the proximal lumen, less H+ becomes bound creating NH4+ and you create an acidodic situation

39
Q

How do we treat RTA Type 4?

A

Treat Hyperkalemia as a result of low aldosterone/lack of response to aldosterone:

  • low K+ diet (cabbage, low K+ fruits)
  • Loop diuretic (Furosemide)

Renal II Quiz II (12 decks)

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