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Renal System > Distal Renal Tubular Diseases > Flashcards

Distal Renal Tubular Diseases Flashcards

1
Q

What mutations cause Bartter syndrome?

A
  • Bumetanide-sensitive Na+-K+-Cl-cotransporter (NKCC2)
  • ATP-sensitive K+ channel (ROMK)
  • Cl- channel A subunit (CLCNKA)
  • Cl- channel B subunit (CLCNKB)
  • Barttin (necessary for insertion of Cl- channel A and B subunits in cell membrane in kidney and inner ear)
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2
Q

Classic Bartter Syndrome is characterized by?

A
  1. failure to thrive
  2. polydipsia
  3. episodes of dehydration
  4. episodes of salt craving
  • Affected patients have hypercalciuria
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3
Q

Difference between Neonatal and classic Bartter Syndrome?

A

Classic:

  • It presents later in infancy
  • do not usually have nephrocalcinosis as do patients with neonatal Bartter syndrome.
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4
Q

Mode of inheritance of Bartter Syndrome?

A

Autosomal recessive

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5
Q

What features distinguish between Bartter and Gitelman?

A
  1. hypomagnesemia
  2. elevated urine magnesium
  3. low urine calcium excretion
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6
Q

Mutations associated with Gitelman Syndrome?

A

mutations in the thiazide-sensitive Na+/Cl- cotransporter (TSC)

(on the luminal side of the distal convoluted tubule)

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7
Q

Bartter syndrome and Gitelman syndrome are both syndromes of what?

A

hypochloremic metabolic alkalosis

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8
Q

Bartter syndrome and Gitelman syndrome are associated with hyperplasia of…?

A

the juxtaglomerular apparatus

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9
Q

What else can cause Hypochoremic metabolic alkalosis?

A
  1. chronic vomiting
  2. diuretic abuse
  3. congenital chloride diarrhea
  4. cystic fibrosis
  5. ingestion of formula deficient in chloride
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10
Q

Why are patients with neonatal and classic Bartter syndromes usually more severely affected than patients with Gitelman syndrome?

A

Mmore severe Na+ wasting in Bartter syndrome than Gitelman’s

  • because Bartter’s syndrome is due to problems in the Thick AL of LOH, where more Na+ should normally take place
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11
Q

What causes Liddle syndrome?

A
  • results from a gain-of-function mutation in the β or γ subunit of the epithelial sodium channel (ENaC).
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12
Q

Mode of inheritance of Liddel Syndrome?

A

Autosomal dominant

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13
Q

Tx of Liddle syndrome?

A
  1. low sodium diet

2. potassium-sparing diuretics.

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14
Q

Liddle syndrome is characterized by?

A
  1. increased absoprtion of sodium
  2. hypertension
  3. hypokalemic metabolic alkalosis
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15
Q

Disease characterized by an inability to concentrate the urine despite normal or elevated levels of the antidiuretic hormone arginine vasopressin (AVP

A

Nephrogenic diabetes insipidus (NDI)

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16
Q

What causes Nephrogenic diabetes insipidus (NDI)?

A

failure of the vasopressin-sensitive water channels (aquaporin 2, AQP2) to insert into the luminal membrane of the collecting duc

  • due to:
    1. defective V2 receptor (90% cases)
    2. Defective AQP2 (10% cases)
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17
Q

Symptoms of Nephrogenic diabetes insipidus?

A
  1. polydipsia
  2. polyuria
  3. irritability
  4. constipation
  5. formula intolerance with vomiting
  6. failure to thrive
  7. hyperthermia
  • Severe dehydration can lead to hypoperfusion of the brain, kidneys, and other organ systems and lead to mental retardation and renal damage. The huge volumes of urine produced can lead to hydronephrosis, megaureter, and bladder dysfunction
18
Q

What is Renal Tubular Acidosis (RTA)?

A

Hyperchloremic metabolic acidosis with a normal plasma anion gap.

19
Q

What does a higher than normal anion gap tell you?

A

Indicates the presence of an unexpected, unmeasured serum anion

20
Q

Examples of unmeasured serum anions that cause an increase in the anion gap?

A

MUDPILES

  • Methanol
  • Uremia
  • Diabetic Ketoacidosis
  • phenformin and Paraldehyde
  • Isoniazide, Infection, Iron
  • Lactic Acidosis
  • Ethylene glycol, ethanol
  • Salicylates
21
Q

Causes of acidosis with a normal anion gap (hyperchloremic acidosis)

A
  1. Renal Tubular acidosis
  2. Exogenous Chloride
  3. GI bicarbonate loss (Diarrhea)
22
Q

Type II Renal Tubular Acidosis

  • where is the defect?
  • what is the result of this defect?
A
  • Proximal Tubule defect
  • leads to a decreased threshold for bicarbonate reabsorption
  • Patients with type II RTA are able to achieve a urine pH less than 5.5 in the face of a low serum bicarbonate. (mostly variable)
23
Q

What RTA is associated with Fanconi Syndrome?

A

Type II RTA

24
Q

Type I Renal Tubular Acidosis (RTA)

A

Characterized by:
- impaired ammonium excretion and impaired acid secretion by alpha-intercaleted cells

  • inability of the collecting duct to decrease the urinary pH BELOW 5.5 even with systemic acidosis (pH > 5.5!)
25
Q

Clinical Presentation of Type I RTA?

A

Patients present with:

  • hyperchloremic
  • hypokalemic metabolic acidosis
  • polyuria
  • dehydration
  • constipation
  • short stature
  • failure to thrive.
  • Inheritance is sporadic or autosomal dominant.
26
Q

Type IV RTA is characterized by:

A

by hyperchloremic metabolic acidosis and HYPERKALEMIA!

27
Q

What causes Type IV RTA?

A

Deficiency of aldosterone or an inability to respond to aldosterone action

  • Urine pH may be LESS than 5.5 during acidosis. (pH
28
Q

Etiologies of Type IV RTA?

A

o Primary mineralocorticoid deficiency (Addison disease, adrenal damage, 21-hydroxylase deficiency, etc.)
o Secondary mineralocorticoid deficiency (hyporeninemic hypoaldosteronism associated with diabetic nephropathy, tubulointerstitial nephropathies, AIDS, etc.)
o Mineralocorticoid resistance (pseudohypoaldosteronism types I and II)
o Renal tubular dysfunction (lupus nephritis, obstructive uropathy, hyperkalemic distal RTA

29
Q

Hyperkalemic disorders:

A
  1. Hypoaldosteronism
    - congenital adrenal hyperplasia
    - congenital adrenal hypoplasia
    - autoimmune
  2. Pseudohypoaldosteronism (PHA)
    - PHA type I
    - PHA type II
    - Tubular injury (obstructive uropathy)
30
Q

HypoKalemic disorders:

A

Hyperaldosteronism

  1. primary (adrenal tumors)
  2. Secondary
    - dehydration
    - sodium-wasting (Bartter, Gitelman)
  3. genetic disorders
    - Glucococorticoid remediable hyperaldosteronism (GRM)
    - Apparent Mineralcorticoid Excess (AME)
31
Q

Glucococorticoid remediable hyperaldosteronism (GRM)

A
  • Results from recombination of the homologous genes for 11-β-hydroxysteroid dehydrogenase (11βHSD) and aldosterone synthase

=> Produces a hybrid molecule that makes aldosterone in response to stress
=> Causes low renin hypertension and hypokalemia

32
Q

Apparent Mineralcorticoid Excess (AME)

A
  • Mutations in kidney isozyme of 11βHSD

=> increased levels of cortisol in the kidney, which cross-reacts and activates the mineralocorticoid receptor

=> Causes low renin hypertension and hypokalemia

33
Q

Characteristics of PHA type 1

A

Presents with hypotension and hyperkalemia associated with renal salt wasting in the neonatal period.

  • Life-threatening: affected individuals are best treated with a high salt diet and prompt fluid resuscitation with sodium-containing fluids in case of volume depletion
34
Q

Chracteristics of PHA Type II?

A

AKA: Gordon syndrome

  • characterized by hypertension with hyperkalemia
  • genetic defect has been identified as mutations in WNK1 and WNK4
    => excessive reabsorption (activation) of the sodium chloride transporter (in DCT)
  • low NaCl to CD => hyperkalemia
35
Q

PHA Type II is very similar to which other distal tubule disease?

A

Gitelman’s syndrome

36
Q

Tx of

  • PHA type I?
  • PHA type II?
A

PHA Type I: potassium-binding resin (Kayexalate)

PHA Type II: Thiazide diuretics

37
Q

How do you test for RTA type IV?

A 
the TTKG (transtubular potassium gradient)
- demonstrates aldosterone activity in the kidney
38
Q

Location of action of Acetazolamide?

A

Carbonic anhydrase inhibitor

- proximal tubule

39
Q

Location of action of Furosemide and Bumetanide?

A

Na/K/2Cl cotransporter

- Thick AL of LOH

40
Q

Location of action of Thiazide diuretics?

A

Na-Cl cotransporter

- DCT

41
Q

Location of action of K-sparing diuretics (amiloride, triamterene)

A

Epithelial Na-channel (ENaC)

- Late DCT and CD

42
Q

Location of action of Aldosterone inhibitors

spironolactone and eplerenone

A

Aldosterone receptor

- Late DCT and CD

Renal System (19 decks)

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