Pathophysiology of Water Handling Flashcards

1
Q

What causes Nephrogenic Diabetes Insipidus?

A

ADH resistance

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2
Q

What causes euvolemia?

A
  • SIADH
  • 1° Polydipsia
  • Hypothyroidism
  • Adrenal Insufficiency
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3
Q

What is SIADH?

A

syndrome of inappropriate ADH secretion; hypoosmolality and less than maximally dilute urine

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4
Q

Sodium is transported on the Na+-K+-2Cl- cotransporter in the ______ and by the thiazide-sensitive NaCl cotransporter in the ______.

A

thick ascending limb; distal convoluted tubule

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5
Q

High serum uric acid levels suggest volume ______.

A

depletion

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6
Q

If the UNa is less than 20 in hypervolemia, the cause is ______.

A
  • CHF
  • cirrhosis
  • nephrotic syndromes
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7
Q

_____ occur with severe or acute hyponatremia.

A

Seizures

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8
Q

Low serum uric acid levels suggest ______.

A

euvolemia

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9
Q

For each increase in serum glucose of ____mg/dL, serum sodium will fall by about ____mEq/L.

A

100; 1.6

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10
Q

What is the equation for Serum osmolality (Sosm)?

A

2 X [Na] + [BUN/2.8] + [Glucose/18]

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11
Q

How do you test for central diabetes insipidus?

A

kidneys should respond to exogenous AVP with a rise in Uosm of 100 mOsm/kg above the levels achieved following water deprivation

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12
Q

______ is transported on the Na+-K+-2Cl- cotransporter in the thick ascending limb and by the thiazide-sensitive NaCl cotransporter in the distal convoluted tubule.

A

Sodium

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13
Q

If the UNa is less than 20 in hypovolemia, the cause is ______.

A

extrarenal losses

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14
Q

What causes Central Diabetes Insipidus?

A

ADH deficiency

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15
Q

What is the tx for minor hyponatremia?

A
  • dietary water restriction
  • Na/Cl +/- furosemide
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16
Q

What are the 3 categories of SIADH?

A
  1. CA
  2. pulmonary disease
  3. CNS disorders
17
Q

Drugs such as ______ antagonize the end-organ effect of AVP.

A

lithium or demeclocycline

18
Q

Water deficits should be restored slowly in order to avoid ______.

A

sudden shifts in brain cell water

19
Q

What is Congenital nephrogenic DI?

A

a rare sex-linked (male) disorder in which cyclic AMP is not generated in response to AVP

20
Q

What causes decreased total body Na?

A
  • GI loss (diarrhea)
  • skin loss (burns)
  • diuretic use without sufficient water intake
  • mechanical ventilation
21
Q

What causes inappropriate ADH secretion?

A
  • Hypothyroidism
  • drugs (nicotine, isoproterenol, SSRIs, morphine, barbs, aspirin)
  • adrenal insufficiency
  • 1a polydispsia
22
Q

What is the normal serum osmolality range?

A

280-295 mOsm/kg

23
Q

Hypernatremia occurs only when (1) ______ or (2)_____.

A
  1. ADH is decreased
  2. ineffective daily water intake (less than that required to compensate for normal insensible, gastrointestinal, and renal losses)
24
Q

What causes Isotonic Hyponatremia?

A
  • hyperlipidemia
  • hyperproteinemia (multiple myeloma)
  • ***this is a lab artifact
25
Q

Sodium is transported on the ______ in the thick ascending limb and by the thiazide-sensitive _____ in the distal convoluted tubule.

A

Na+-K+-2Cl- cotransporter; NaCl cotransporter

26
Q

Low serum _____ levels suggest euvolemia.

A

uric acid

27
Q

For each increase in serum _____ of 100 mg/dL, serum _____ will fall by about 1.6mEq/L.

A

glucose; sodium

28
Q

If the UNa is greater than 20 in hypervolemia, the cause is ______.

A
  • ARF
  • CKD
29
Q

If the UNa is greater than 20 in hypovolemia, the cause is ______.

A

renal losses

30
Q

Drugs such as lithium or demeclocycline antagonize the end-organ effect of _____.

A

AVP

31
Q

High serum ____ levels suggest volume depletion.

A

uric acid

32
Q

Hyponatremia is most commonly caused by _____.

A

a relative excess of water

33
Q

What causes Hypotonic Hyponatremia?

A

the nonosmotic release of ADH that prevents maximal urinary dilution –> need to check the volume status next

34
Q

What 2nd messenger does ADH use?

A

adenylate cyclase (which generates cyclic AMP)

35
Q

What causes Hypertonic Hyponatremia?

A
  • hyperglycemia
  • mannitol or glycerol administration
36
Q

What are the 3 main categories of hyponatremia?

A
  1. hypertonic
  2. isotonic
  3. hypotonic
37
Q

What causes increased total body Na?

A

hypertonic fluid administration

38
Q

______ is a rare sex-linked (male) disorder in which cyclic AMP is not generated in response to AVP.

A

Congenital nephrogenic DI