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Clin Med Exam 4 > Hypernatremia and hyponatremia-Paulson > Flashcards

Hypernatremia and hyponatremia-Paulson Flashcards

1
Q

Hypernatremia is defined as:

A

Elevated serum sodium > 145 mEq/L

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2
Q

Hypernatremia: MC etiology?

A

**most often from water depletion (think elderly Pt with dementia who doesn’t remember to drink H20)

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3
Q

Remember Sodium is the main extracellular _____

A

cation

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4
Q

Which Pt demographic is at the highest risk for hypernatremia?

A

Elderly patients with ↓ thirst and ↓ access to fluids are at highest risk

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5
Q

General- Hypo/hypernatremia

A

Sodium concentration can increase or decrease.

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6
Q

Define hypervolemia

A

fluid volume is increased

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7
Q

Define hypovolemia

A

fluid volume is decreased

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8
Q

Euvolemia=

A

Fluid volume is relatively unchanged

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9
Q

Pathophysiology Hypernatremia: again, what is the MC cause?

A

-Almost always from inadequate fluid intake or excess water loss –Think: elderly, dementia patients who forget to drink fl

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10
Q

Water losses: (can occur through?) list 3 ex’s

A

-Skin -GI tract -Urine

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11
Q

Describe how water can be lost through urine

A

-Osmotic diuresis -Diabetes insipidus (central or nephrogenic) -Diuretics can waste water and/or sodium (ie thiazide diuretics)

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12
Q

Describe the Pathophys: -Hypervolemic hypernatremia

A

-Iatrogenic from hypertonic saline or dialysis (specifically normal saline, giving a Pt extra fluids (volume)) -Hyperaldosteronism (increased aldosterone INCREASES the amount of Na reabsorbtion–> causes water to follow and be absorbed)

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13
Q

Describe the Pathophys: -Hypovolemic hypernatremia

A

-Renal losses from renal disease or diuretics -Extrarenal losses (ie diarrhea, vomiting)

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14
Q

Describe the Pathophys: -Euvolemic hypernatremia

A

-Hypodipsia (=decreased thirst and water intake, ie diabetes inspididus) -Diabetes insipidus

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15
Q

Hypernatremia: Clinical Features -Early Sx? -Next? -Neuro Sx? -S/s of dehydration?

A

-Early sx: anorexia, restlessness, n/v -Next: progressive AMS: lethargy or irritability 1st, then stupor or coma -Neurologic s/s: twitching, hyperreflexia, ataxia, tremor, seizures -S/S of dehydration: Dry MM, tenting/poor skin turgor, lack of tears, ↓ salivation, tachycardia, hypotension, oliguria/anuria

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16
Q

Diabetes insipidus=

A

=production of dilute urine -central diabetes insipidus= decreased posterior pituitary production of ADH (antidiuretic hormone) -Nephrogenic DM Inspidus= reduced sensitivity of the kidneys to ADH (so someone with diabetes insipidus IS NOT reabsorbing water as they should)

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17
Q

Osmotic diuresis=

A

take in some solute that does NOT get reabsorbed into your body (ie glucose, urea, manatol) NOT sodium (not an electrolyte solute), and what happens is all the water follows that solute and you end up with increased urine

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18
Q

Chronic hypernatremia: -defined as?

A

Chronic: has been present ≥ 2 days -Less likely to provoke neurologic s/s -Many patients have underlying neuro disease (impaired thirst) -Undergo brain adaptation to hypernatremia

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19
Q

Acute Hypernatremia: -is defined as? -more likely to provoke _____ sx?

A

More likely to provoke neurologic s/s (notes: rapid decrease in brain volume, can cause SAH (subarachnoid hem. and irreversible brain damage)

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20
Q

Hypernatremia: -diagnostic labs

A

-Cause is usually obvious from the history -**BMP–> Sodium >145 -Urine & plasma osmolality if etiology unclear

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21
Q

what can the urine and plasma osmolarity tell you?

A

-If hypernatremic & plasma osmolality >295, normal response would be to ↑ ADH production –> excrete low volumes (<500 mL/day) of very concentrated urine (with osmolality >800) -If so, there’s an extrarenal cause -If urine osmolality < plasma –> DI (notes: plasma osmolarity–> looks at

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22
Q

Hypernatremia: tx?

A

Give dilute fluids to correct the deficit & replace ongoing losses

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23
Q

Chronic hypernatremia: tx?

A

-Chronic: Correction must be slow –To avoid rapid fluid movement into the brain –>cerebral edema –Can lead to seizures and coma -D5W IV at a rate of **1.35 mL/hr x weight in kg –For a 50 kg patient, this would work out to about 70 mL/hr –The goal of this regimen is to lower the serum sodium by a max of 10 mEq/L over a 24 hour period -*Recheck serum sodium/glucose 4-6 hours after tx initiation (D5W=half normal saline)!!! never use normal saline

24
Q

Acute hypernatremia: tx?

A

Acute: -D5W IV at a rate of 3-6 mL/kg per hour -Monitor sodium & glucose Q1-2H until Na < 145 –At this point, you can decrease the rate to 1 mL/kg per hour until they reach a sodium of 140. -Goal is to reduce the sodium by 1-2 mEq/L each hour

25
Q

Calculated Free water deficit

A

Calculated free water deficit: Water deficit = Current TBW x ((serum [Na]/140) - 1) *this is used to figure out the fluids you need to replace) free water= electrolyte free water= pure water that has been depleted from the Pt’s body -dont memorize this calc just focus on treatment options

26
Q

Rate of correction (for water deficit): -Chronic?

A

Chronic: no more than 10 mEq/L per day -Total amount for 1st day: 3 ml/kg of body weight x 10 –>Then divide that number by 24 hours

27
Q

Rate of correction (for water deficit): -acute?

A

Acute: Lower to near normal in the first 24 hours -Hourly rate > total water deficit ÷ 24 hours -Also account for ongoing losses

28
Q

Hypernatremia: prognosis

A

-Mortality rates of 40-60% –Many with underlying severe diseases -Associated with increased M&M (mortality and morbidity): -Perioperative 30-day mortality -Perioperative major coronary events -Pneumonia -VTE

29
Q

Hyponatremia is defined as:

A

-Sodium < 135 mEq/L -*MC electrolyte disorder seen in hospitalized patients

30
Q

Describe the 2 scenarios where a Pt can be hyponatremic

A

-Hypervolemic: Fluid overload Water is either added or retained –> the amount of sodium in the serum is diluted -Hypovolemic: Water and sodium is lost (but more sodium than water) –>can be through renal loses and extrarenal losses

31
Q

Hyponatremic: -describe Hypervolemic causes

A

=Fluid overload –Water is either added or retained –> the amount of sodium in the serum is diluted **Ex’s= CHF, cirrhosis, IVF, nephrotic syndrome

32
Q

Hyponatremic: -Describe Hypovolemic causes –Renal losses vs Extrarenal losses?

A

=Water and sodium is lost (but more sodium than water) -Renal losses: Diuretics, especially **thiazide diuretics -Extrarenal losses: Diarrhea, sweating, blood loss, fluid shifts

33
Q

Pathophysiology- Euvolemic Hyponatremia: -list possible causes (5)

A

-Adrenal insufficiency -Polydipsia -Hypothyroidism -Syndrome of Inappropriate Antidiuretic Hormone (SIADH) -Reset Osmostat

34
Q

Pathophysiology- Euvolemic Hyponatremia: -Polydipsia–> can be primary or _____

A

psychogenic

35
Q

Pathophysiology- Euvolemic Hyponatremia: -List causes of Syndrome of Inappropriate Antidiuretic Hormone (SIADH) (list 4)

A

-Intracranial pathology -Paraneoplastic syndrome (tumor secretes ADH) -Pulmonary disease -Medications: SSRI, cyclophosphamide (think brain bleed, brain tumor= ie any intracranial pathology, stroke, OR pulmonary disease (lung cancer, COPD, and MEDS are a big one)

36
Q

Reset osmostat=

A

=the kidneys retains their ability to approp. concentrate the urine, but the threshold for ADH secretion gets reset DOWNWARDS–> so Pt’s have a chronic mild or low hyponatremia –sometimes considered a variant of SIADH

37
Q

Meds that cause hyponatremia: (slide 16 any are possible, but Paulson listed these main ones)

A

-thiazide diuretics -antipsychotics -SSRI’s (are huge cause of hyponatremia!!!) -say they’re euvolemic and they are on an SSRI–> titrate the SSRI down, or switch meds

38
Q

Classification by tonicity: (another method of classification for hyponatremia-tonicity describes the serum osmolality) -3 types of tonicity

A

-Hypotonic -Isotonic -Hypertonic

39
Q

Describe Hyptonic

A

=less concentrated than normal saline *-SIADH *-Effective arterial blood volume depletion–>CHF, cirrhosis, diuretics *-Endocrine d/o: hypothyroid, adrenal insufficiency *-Advanced renal failure (lose the ability to concentration our urine properly, so water can be retained, serum is more dilute than it should be)

40
Q

Describe Isotonic=

A

=same concentration **-Pseudohyponatremia: ↑ serum lipids or proteins can lead to an erroneous measurement of sodium levels KNOW THIS–> is someone has a high lipid level or serum protein (ie multiple myeloma increase in bence jones)–> can lead to a “fakeout” of sodium level (there is a reduction in the fraction (portion of serum) that is water and sodium so you get an artificially low sodium level)

41
Q

Describe hypertonic=

A

=more concentrated than normal saline **-Significant hyperglycemia Mannitol, maltose, or sucrose retention **-These solutes cause a shift of water out of cells–> sodium is diluted KNOW this–> Pt that is signif. hyperglycemic, water that was inside cells is now in the serum–> causes serum dilution of sodium– just correct the sodium level for this

42
Q

Algorithmic for hyponatremia

A

slide 18

43
Q

Hyponatremia: clinical features -at what sodium serum level are Pts symptomatic? -S/Sx?

A

-Usually not symptomatic until Na is 125-130 -May complain of: anorexia, n/v, lethargy, disorientation, headache, seizures -Signs: Weakness, agitation, hyporeflexia, orthostatic hypotension, delirium, coma, seizure, respiratory arrest, brainstem herniation

44
Q

Another cause of hyponatremia?

A

contrast agents

45
Q

Hyponatremia: diagnostic labs?

A

-Focus on finding underlying cause *-1st: BMP + serum osmolality –Osmolality can further direct you to a hypotonic, isotonic, or hypertonic cause -Urine osmolality & electrolytes also helpful -Other possibilities: TSH, plasma cortisol, ACTH stimulation test, brain or lung imaging

46
Q

Serum sodium algorithm (starting with plasma osmolality)

A

slide 21 , Paulson not testing on this but schoenwald might -first use your inspection skills and check their volume status first and go from there

47
Q

d

A

slide 22

48
Q

Classifications of hyponatremia: -acute ? -subacute? -chronic ?

A

-Acute: developed within the last 24 hours -Subacute: 24-48 hours -Chronic: >48 hours

49
Q

Classifications of hyponatremia: -severe? -moderate -mild?

A

-Severe: Sodium is ≤ 120 -Moderate: 121-129 -Mild: 130-135

50
Q

Hyponatremia: tx?

A

-Identify & treat underlying cause -If symptomatic, even if mild, need emergency therapy –Hypertonic saline -Goal is to raise Na by 4-6 over a couple hours –Should alleviate symptoms & prevent herniation –Check sodium Q2H -For non-emergency therapy, the goal is to bring Na up slowly -Overly rapid correction can cause osmotic demyelination syndrome (aka central pontine myelinolysis)

51
Q

Hyponatremia: tx -Hypovolemic?

A

tx with Isotonic saline

52
Q

Hyponatremia: tx -Hypervolemic?

A

-CHF, cirrhosis: diuresis, fluid restriction, sodium restriction -Renal failure: fluid restriction, dialysis, sodium restriction

53
Q

Hyponatremia: tx -Euvolemic

A

-Fluid restriction –SIADH- may add salt tabs and/or a loop diuretic

54
Q

What is an off-label med used for SIADH?

A

*Demeclocycline

55
Q

When is Demeclocycline used? -S/E?

A

-Often used for patients who don’t respond to salt tabs/loop diuretics -S/E: renal toxicity (especially for patients with cirrhosis), can cause nephrogenic DI, intracranial hypertension

Clin Med Exam 4 (14 decks)

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