Lecture 5: Acquired and Congenital Tubular Functional Defects & RTA Flashcards

1
Q

Fanconi Syndrome is a disease affecting which part of the nephron?

A

Proximal tubules

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2
Q

In Fanconi Syndrome there will be high levels of what in the urine?

A
  • Glucose
  • AA’s
  • Uric acid
  • Phosphate
  • HCO3-
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3
Q

Major clinical features of Fanconi Syndrome?

A
  • Polyuria, polydipsia and hypovolemia
  • Growth failure
  • Hypokalemia
  • Hyperchloremia (due to HCO3- loss)
  • Hypophosphatemia/phosphaturia
  • Glycosuria + proteinuria/aminoaciduria + hyperuricosuria
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4
Q

Hypophosphatemia associated w/ Fanconi Syndrome is responsible for what serious consequence in children and in adults?

A
  • Children = hypophsphatemic rickets
  • Adults = osteomalacia
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5
Q

What type of renal tubular acidosis is due to Fanconi Syndrome?

A

Type 2 renal tubular acidosis

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6
Q

What are 5 acquired causes of Fanconi Syndrome?

A
  • Maleic acid
  • Malignancy
  • Multiple myeloma
  • Nephrotic Syndrome
  • Renal transplantation
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7
Q

What are some medications which can cause Fanconi Syndrome?

A
  • Adefovir and Tenofovir
  • Cisplatin (chemotherapy)
  • Aminoglycosides (i.e., gentamicin)
  • Outdated Tetracycline
  • Valproate
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8
Q

What is the therapy for Fanconi Syndrome?

A
  • Replace substances wasted in urine
  • HCO3- (can use citrate), phosphate + Vit D
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9
Q

Sx’s of Bartter Syndrome are identical to those of pts taking what drugs?

A

Loop Diuretcs

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10
Q

Bartter Syndrome is associated with defective transport where in the nephron?

A

Loop of Henle

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11
Q

How does the neonatal form of Bartter Syndrome present?

A
  • Seen at 24-30 wks of gestation as polyhydramnios; polyuria/polydipsia
  • Hypercalciuria after birth
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12
Q

What is the typical onset and presentation for the “classic” form of Bartter Syndrome?

A
  • No noticeable sx’s until around school age (i.e., kindergarten and above)
  • Present w/ polyuria/polydipsia
  • May also see vomiting and growth retardation
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13
Q

What is used in the treatment of Bartter Syndrome?

A
  • Life-long increases in dietary Na+ and K+
  • Potassium-sparing diuretics
  • NSAIDs
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14
Q

Why are NSAIDs useful in treating Bartter Syndrome?

A
  • PGE2 directly stimulates renin release and contributes to electrolyte abnormalities
  • NSAIDs block and help correct this
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15
Q

Which levels will be elevated in Bartter Syndrome?

A
  • Elevated plasma renin and aldosterone
  • Hyperglycemia
  • Hyperuricemia
  • Increased cholesterol and TAG’s
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16
Q

What is the urine osmolality like in Bartter Syndrome?

A

Isotonic urine

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17
Q

Which acid base disturbance is present in Bartter Syndrome?

A

Hypochloremic metabolic alkalosis

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18
Q

Gitelman Syndrome is due to a defect in which transporter and in which part of the nephron?

A
  • Na+-Cl- Symporter
  • Distal Tubule
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19
Q

When does Gitelman Syndrome typically present?

More severe in which sex?

A
  • Presents in late childhood or adulthood
  • MORE severe in females
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20
Q

Gitelman Syndrome pts have mutations in gene for which cotransporter?

Mimics chronic use of what drug?

A
  • Thiazide-sensitive Na-Cl cotransporter (NCCT)
  • Mimics chronic use of thiazide diuretics
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21
Q

Pts with Gitelman Syndrome may develop what at a later age?

A

HTN

22
Q

What are major lab findings in Gitelman Syndrome?

What type of acid-base disturbance?

A
  • Hypokalemia + Hyponatremia + Hypomagnesemia (may be severe)
  • Hypercalcemia
  • Hypochloremic metabolic alkalosis
  • Hyperglycemia + Hyperuricemia
  • Increased cholesterol and TAGs

*Think about how thiazides work!!!

23
Q

What kind of urine osmolality can you see with Gitelman Syndrome?

A

Dilute or concentrated

24
Q

What is the treatment of Gitelman Syndrome focused on?

Given what?

A
  • Cornerstone = taking in enough NaCl to avoid Na+ depletion
  • Providing K+ and Mg2+ supplementation
  • Aiming for asymptomatic stable hypokalemia and borderline hypomagnesemia
25
Q

Effect of NSAIDs on Gitelman Syndrome?

A

Ineffective

26
Q

How do calcium levels differ in Gitelman vs. Bartter Syndrome?

A
  • Bartter = HYPOcalcemia/hypercalciuria
  • Gitelman = HYPERcalcemia/hypocalciuria
27
Q

How are urine chloride concentration in a pt w/ Bartter or Gitelman Syndrome vs. someone who secretively takes diuretics?

A
  • Typically >25 mEq/L despite volume contraction in the syndromes
  • Pt secretively taking diuretics have variable urine chloride concentration
28
Q

Failure to respond to what can aid in the diagnosis of Barterr or Gitelman Syndrome?

A
  • Failure of response to thiazide is clue for Gitelman syndrome
  • Failure of response to loop diuretic is clue for Bartter syndrome
29
Q

In Liddle Syndrome (pseudoaldosteronism) which channel is mutated and in which part of the nephron?

A
  • ENaC channels of principal cells
  • Collecting duct
30
Q

Which ion disturbances result in Liddle Syndrome?

Leads to what clinical sx, lab values, and acid-base disturbance?

A
  • Na+ reabsorption w/ K+ loss
  • Producing early and often severe HTN
  • Associated w/ LOW plasma renin + LOW aldosterone
  • Metabolic acidosis
31
Q

Liddle syndrome is treated with what combination?

A

Low sodium diet + K-sparing diuretics

32
Q

Pseudohypoaldosteronism is caused by failure of what?

Leads to what?

What are the levels of aldosterone like?

A
  • Failure of response to aldosterone leasing to renal tubular acidosis and hyperkalemia
  • Aldosterone levels = elevated
33
Q

Therapy for pseudohypoaldosteornism requires large amounts of what?

A

Sodium

34
Q

What is the primary defect in RTA type 1?

A

Impaired distal H+ secretion

35
Q

What is the urine pH like in RTA Type 1?

A

Typically >5.5

36
Q

Common secondary causes of RTA Type 1?

A

Autoimmune disorders (i.e., SLE, Sjogrens and RA)

37
Q

What is the primary defect in RTA Type 2?

A

Impaired proximal HCO3- reabsorption

38
Q

Common secondary causes of RTA Type 2?

A
  • In children as part of Fanconi’s syndrome
  • In adults as mutliple myeloma or drugs (i.e., tenofovir, ifosfamide, gentamicin, outdate tetracycline)
39
Q

What is the primary defect in RTA type 4?

A

Lack of aldosterone or failure of response to it

40
Q

Which plasma value differentiates RTA type 4 from the other two?

A

High plasma K+

41
Q

Common secondary causes of RTA type 4?

A
  • Diabetic nephropathy –> low aldosterone
  • Chronic interstitial nephritis
  • Drugs –> ACEIs, ARBs, heparin, NSAIDs, spironolactone, others..
42
Q

Location of defect in RTA type 1 vs. type 2 vs. type 4?

A
  • Type 1 = Distal tubules
  • Type 2 = Proximal tubules
  • Type 4 = Adrenal
43
Q

Which RTA presents with the most severe acidosis?

A

RTA type 1

44
Q

Which RTA is associated with urinary stone formation due to hypercalciuria w/ low urinary citrate and alkaline urine + bone dimineralization?

A

RTA type 1

45
Q

Which 4 findings sum together to equal renal tubular acidosis?

A

Acidemia + Normal Anion Gap + Normal Serum Cr + No diarrhea

46
Q

Major consequence of RTA type 1 is low levels of what?

Can lead to what clinical problems?

A
  • Low blood K+
  • Leading to extreme weakness, irregular heartbeat, and paralysis
47
Q

Untreated RTA type 1 leads to what in chidlren and adults?

A
  • Growth retardation in children
  • Progressive kidney and bone disease in adults
48
Q

What is given as treatment for RTA type 1?

A

Sodium bicarbonate or sodium citrate to tx acidosis

49
Q

Children w/ RTA type 2 would likely receive what as treatment?

A

Large doses of potassium citrate, an oral alkali

50
Q

In RTA type 4, low aldosterone leads to high K+ and a decrease in the synthesis of what?

How does this play a role in the acidosis?

A

↓ NH3 synthesis by PT

*HCO3- is generated by having NH3 accept H+ –> NH4 to mainatain acid-base homeostasis

51
Q

What 2 things are done for treatment of RTA type 4?

A
  1. Low K+ diet and a loop diuretic (K+-wasting)
  2. Alter drug doses and/or change drugs (i.e., spironolactone, ACEIs, ARBS, NSAIDs)
52
Q

Which congenital renal tubule disorder of the nephron is associated with increased plasma renin and aldosterone?

A

Bartter Syndrome