SM 214a - Hypernatremia Flashcards

1
Q

Hypertonic hypernatremia is recognized as a SNa above…

A

145 mEq/L

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2
Q

What two things can cause hypertonic hypernatremia (dehydration?)

A
  • Salt intake
  • Persistent H2O losses not replaced by H2O intake
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3
Q

If a patient has hypernatremia (Na+ >145) and ther urine osmolality is high, what is the cause?

A

Insensible losses or GI loses

+
Decreased H2O intake

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4
Q

What is the treatment for hypernatremia resulting from sweating, GI loss, or solute diuresis?

A

Need to replace Na+, K+, and H2O

Use 0.9% or 0.45% saline with potassium

Caution: Do not cause serum Na to fall too quickly!

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5
Q

What factors could impair H2O diuresis?

A
  • ADH release
    • -> Reabsorption of water
  • Decreased renal solute load
    • -> Decreased osmotic pressure in the tubule
    • -> Increased H2O reabsorption
  • Volume depletion
    • -> Decreased filtration
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6
Q

What is the treatment for nephrogenic DI?

A

Low sodium, low protein diet
+
Thiazide diuretics
+
NSAIDS

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7
Q

How do you estimate the water deficit in a patient with hypernatremia?

A

Current TBW x ( [SNa ÷ 140] – 1)

  • TBW in men is 0.6 * lean body weight (kg)
  • TBW in women is 0.5 * lean body weight (kg)
  • TBW in the elderly is 0.45 * lean body weight (kg)
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8
Q

What are the causes of polyuric hypertonic hypernatremia

(increased CefH2O)

A
  • Solute diuresis
    • Gluose (diabetics)
    • Mannitol
    • Urea
    • Diuretics
  • Pure H2O diuresis
    • Central Diabetes Insipidus
    • Nephrogenic Diabetes Insipidus
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9
Q

How much water do we lose from insensible losses?

How?

A

~500 ml/day/m2 or 800 ml/day for a 70 Kg person

  • 60% is through the skin
  • 40% through respiration
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10
Q

A diabetic with polyuria will be [hypo/hyper]kalemic

A

A diabetic with polyuria will be hypokalemic

  • Increased glucose in the tubule
  • -> Increased water in the tubule
  • -> Increased salt in the tubuel
  • -> Increased Na+ delivery to the collecting duct
  • -> Increased Na+ reabsorption
  • -> Increased K+ secretion
  • -> Hypokalemia
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