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Flashcards in 19. Renal tubular defects Deck (41):
1

Renal tubular defects - types

1. Fanconi syndrome
2. Bartter syndrome
3. Gitelman syndrome
4. Liddle syndrome
5. Syndrome of apparent minelocorticoid excess

2

Fanconi syndrome- pathophysiology

Generalized reabsorptive defect in early proximal convoluted tubule

3

Fanconi syndrome --> .... (result in )

increased amino acids, glucose , HCO3- and PO4- ---Metabolic acidosi (proximal renal tubular acidosis)

4

causes of Fanconi syndrome

1. hereditary defects ( wilson disease, tyroseninemia, glycogen storage disease, cystinosis)
2. ischemia
3. multiple myeloma
4. nephrotoxins/ drugs ( expired tetracyclines, ifosfamide , cisplatin, tenofovir, lead poisoning)

5

nephrotoxins/ drugs that cause Fanconi syndrome

expired tetracyclines, ifosfamide , cisplatin, tenofovir, lead poisoning)

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Bartter syndrome- pathophysiology ( and result in)

Reabsorptive defect in thick ascending loop of Henle --> affects Na+? K+?2CL- contrasporter

7

Bartter syndrome .... (result in )

1. hypokalemia
2. metabolic alkalosis
3. hypercalciuria

8

Situation that mimics Bartter syndrome

chronic loop diuretic use

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Loop diuretics - deugs

1. Furosemide
2. Butabude
3. torsemide
4. Ethacrynic acid

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Bartter syndrome - mode of inheritance

AR

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Gitelman syndrome - pathophysiology

Reabsorptive defect in distal convoluted tubule

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Gitelman syndrome - mode of inheritance

AR

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situation that mimics Gitelman syndrome

lifelong thiazide diuretics

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thiazide diuretics:drugs

1. hydrochlorothiazine
2. CHlorothalidone
3. Metolazone

15

Gitelman syndrome---> .... (results in )

1. hypokalemia
2. hypomagnesia
3.metabolic alkalosis
4. hypocalciuria

16

Gitelman syndrome vs Bartter syndrome according to severity

Bartter syndrome is more sever

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Liddle syndrome - pathophysiology

gain of function mutation --> increased Na+ reabsorption in collecting tubules ( high activity of epithelial channels)

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situation that mimics Liddle syndrome

hyperaldosterinism ( but aldosterone is nearly undetectable)

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Liddle syndrome - mode of inheritance

AD ( gain function mutation)

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Liddle syndrome --> .... (result in )

1. hypertension
2. hypokalemia
3. metabolic alkalosis
4. low aldosterone

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Liddle syndrome - treatment

amiloride

22

Syndrome of apparent minelocorticoid excess - pathophysiology

hereditary deficiency of 11β-hydroxysteroid dehydrogenase which normally converts cortisol ( can activate mineralocorticoid receptors) to cortizone ( inactivate on mineralocoticoid receptors) in cell containing minrealocortioid receptors --> increased mineralocoirticoid activity

23

Syndrome of apparent minelocorticoid excess - manifestations

1. hypetension
2. hypokalemia
3. metabolic alkalosis
4. Low erum aldosterone levels

24

situation that mimics Syndrome of apparent minelocorticoid excess

glycyrrhetinic acid ( present in licorice ) which blocks activity of 11β-hydroxysteroid dehydrogenase

25

Licorice, is the root of

Glycyrrhiza glabra from whic a sweet flavour can be extracte ( wide variety of candies or sweets)

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apparent minelocorticoid excess - treatment

corticosteroids --> decreases endogenous cortisol production --> decrease mineralocorticoid receptor activation

27

• A man has hypertension. Serum studies: hypokalemia and metabolic alkalosis. Aldosterone is low. Could this disorder be acquired?

Yes, these findings are consistent with 11β-hydroxysteroid dehydrogenase deficiency (SAME), which may be acquired from glycyrrhetic acid

28

• A patient with Wilson disease has a low body pH. Urine studies show elevated protein and glucose. Where in the kidney is the likely defect?

A PCT reabsorptive defect causes HCO3-, PO43-, amino acid, and glucose losses in urine (this is Fanconi syndrome [due to Wilson disease])

29

• A man with lymphoma received an excess of cyclophosphamide at his last chemotherapy session and now has a metabolic acidosis. What happened?

The nephrotoxic cyclophosphamide has caused Fanconi syndrome (reabsorptive defect in the PCT that results in metabolic acidosis)

30

• Bartter syndrome is a reabsorptive defect in the thick ascending loop of Henle. Which cotransporter does it affect?

The Na+/K+/2Cl- cotransporter

31

• Gitelman syndrome is a defect of ____ reabsorption in the DCT.

NaCl

32

• A man with an autosomal recessive disorder presents with hypokalemia and a high body pH but a normal urine calcium level. Diagnosis?

Gitelman syndrome (high calcium in the urine is seen with Bartter syndrome)

33

• A chronic hypertension patient has low K+ levels. He has an autosomal dominant kidney disorder affecting the collecting tubules. Treatment?

Amiloride (the patient has Liddle syndrome)

34

• Liddle syndrome is an increase in Na+ reabsorption in the ____ tubules of the kidneys.

Collecting

35

• A patient has hypokalemia and a metabolic alkalosis. Aldosterone is low, blood pressure is high. Is this an ion channel issue?

Yes (this combination of findings is consistent with Liddle syndrome, with abnormally increased renal sodium channel activity)

36

• A black licorice addict has hypertension, low K+, and a metabolic acidosis. To what hereditary deficiency is this condition similar?

A hereditary deficiency of 11#946;-hydroxysteroid dehydrogenase (syndrome of apparent mineralocorticoid excess)

37

• Name some causes of Fanconi syndrome.

Hereditary (Wilson disease, tyrosinemia, glycogen storage), ischemia, multiple myeloma, toxins/drugs (old tetracyclines, tenofovir), lead

38

• What are the prominent serum and urine electrolyte abnormalities seen in Gitelman syndrome?

Hypokalemia, hypomagnesemia, metabolic alkalosis (blood), and hypocalciuria (urine)

39

• What are the prominent serum and urine electrolyte abnormalities seen in Bartter syndrome?

Hypokalemia, metabolic alkalosis (blood), and hypercalciuria (urine)

40

• What are the prominent serum electrolyte abnormalities seen in Liddle syndrome?

Hypokalemia and metabolic alkalosis

41

• A man with a collecting tubule gain of function mutation has hypertension despite low serum aldosterone. Too much of what ion is reabsorbed?

Sodium (this is Liddle syndrome)

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