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Tins lyte abnormalaties Flashcards

1
Q

Substances that contribute most to osmotic pressure in ECG

A

Na+, HCO3-, CL- and glucose

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2
Q

Formulation to calculate effective osmolality (tonicity)

A

2XNA+ + glucose/18 (range 275-290mOsm/L)

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3
Q

Fluid percentages

A

TBW 60%
ICF 40%
ECF 20% of which 15% IF and 5% IVF
IF = interstitial fluid (extravascular) and IVF is intravascular

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4
Q

Hyponatremia definition

A

Serum Na+ <138 mEq/L

Symptomatic at 135

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5
Q

Epidemiology of hyponatremia

A

Mild is common (15-30%) but only 4% have sodium below 130mEq/L
50% of cases are iatrogenic

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6
Q

Hyperosmolar hyponatremia

A

> 295 mOsm/kg H2O

common in hyperglycemia, each 100mg/dL in plasma glucose above normal (100mg/dL) drops serum Na+ by 1.6 mEq

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7
Q

Iso-osmolar hyponatremia

A

275-295 mOsm/kg
Severe hyperproteinemia or hyperlipidemia causes displacement of serum water (some labs use instruments to avoid this lab error)

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8
Q

MDMA hyponatremia

A

Induces inappropriate secretion of ADH and causes increased gut water reabsorption

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9
Q

Clinical features of hyponatremia

A

Moderately severe start at 130mEq/L
Headache, nausea, disorientation, confusion, agitation, ataxia and areflexia
Severe ate 120mEq/L Intractable vomiting, seizures, coma, resp arrest from brainstem herniation

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10
Q

Post exercise hyponatremia

A

From too much solute free fluid. Check for bloating, nausea, vomiting and edema at wrists and fingers

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11
Q

Osmotic Demyelination Syndrome

A

Rapid correction of hyponatremia (<12 mEq/L/24h) as water moves from cells to ECF (intracellular dehydration)
Symptoms are dysarthia, dysphagia, lethargy, parapereis or quadriparesis, seizurescomadeath

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12
Q

Hypernatremia definition

A

Na+ > 145mEq/L AND hyperosmolality (>295 mOsm/L)

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13
Q

Patho hypernatremia

A

Deficit in TBW or less commonly net gain of Na+
Needs a limit of sense of thirst, availability of water, kindeys ability to concentrate urine
May cause intracranial hemorrhage if too quick
Severity of symptoms based on onset (fast onset = worse symptoms like hyponatremia)

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14
Q

Hypovolemic hypernatremia

A

Decreased TBW and total body Na+ with a relatively greater decrease in TBW)

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15
Q

Hypervolemic hypernatremia

A

Increased total Na+ with normal or increased TBW

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16
Q

Normovolemic hypernatremia

A

Normal sodium with decreased TBW

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17
Q

Clinical features of hypernatremia

A

Nausea, vomiting, lethargy, weakness, increased thirst, low water intake, salt intake, polyuria (greater than 3000mL/hr of urine/24h)

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18
Q

Hypernatremia predisposing risk factors

A

Beeties, hypercalcemia hypokalemia, lactulose, loop diuretics, lithium, demeclocycline or NSAIDS (interstitial nephritis)

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19
Q

Hypernatremia physical exam

A

Hypotension, tachycardia, orthostatic pressure, sunken eyes, dry mucous membranes, altered mental status, poor skin turgor, edema in hypervolemic hypernatremia
Cushings syndrome - moon face, fatty deposits

20
Q

TX hypernatremia

A 
Tx volume deficits first
then cause (diabetes insipidus) vomiting diarrhea fever then free water deficit
21
Q

Diabetes insipidus

A

Ability of kidney to reabsorb free water is compromised
Neurogenic due to inadequate ADH
Nephrogenic from renal causes (v2R receptors don’t respond properly to ADH)

22
Q

Diabetes insipidus characterized by

A

polyuria, polydipsia, increased volume of hypo-osmolar urine

23
Q

Normal K+

A

98% intracellular, 75% in muscles
150mEq/L intracellular
3.5-5 mEq/L extracellular

24
Q

K+ in the kidneys

A

Filtered freely through renal glomerulus then reabsorbed in proximal and ascending tubules, secreted in distal tubule in exchange for Na+

25
Q

Things that cause K+ shift

A

Surgical stress, trauma, burns, acid-base imbalance, catabolic states, increased extracellular osmolality, insulin deficiency
(possible to have hyperk+ with reduced TB K+ and other way around)

26
Q

K+ and pH

A

K+ rises 0.6mEq/L for every 0.1 decrease in PH and vice versa through H+ and K+ exchange

27
Q

HypoK+ definition

A

Serum <3.5mEq/L
Common are fasting, eating disorders, ETOH abuse, alkolosis, insulin, B2-agonists, hypokalemia periodic paralysis
Vomiting, nasogastric suction, diarrhea
Diuretics, hyperaldosteronism, osmotic diuresis, toxins

28
Q

HypoK+ manifestations

A

Effect every system
Makes resting membrane more electronegative, enhancing depol and delays repol
Prolonged QT, flattened T waves, appearance of U waves
Starts at <2.5mEq/L usually

29
Q

Arrythmias of hypoK+

A

A fib, torsades, v tach and v fib

30
Q

HyperK definition

A

> 5.5 mEq/L

31
Q

Diuretics that cause hypoK

A

Carbonic anhydrase inhibitors, loop diuretics, thiazide-like diuretics)
Alkalosis is another common cause
Excessive Chaw, licorice, hyperaldosteronism can also cause it
Same with heavy sweat, heat stroke, fever, hypomagensia, leukemia, hypothermia

32
Q

Causes of pseudo hyperK

A

Tourniquet use, hemolysis, leukocytosis, thrombocytosis

33
Q

Intra to extracellular shifts causing hyperK

A

Acidosis, exercise, B-blockade, insulin deficiency, dig

34
Q

HyperK diuretics

A

Renal failure is a common cause of hyper K+
Potassium-sparing diuretics, b-blockade, NSAIDS, ACE inhibitors and Angio II blockers
Aldosterone deficiency

35
Q

HyperK in da heart

A

Less electronegative resting membrane, partial depol which reduces activation of voltage-dependent sodium channels. Slower and reduced amplitude of action potential
Calcium antagonizes effects of hyperK by raising threshold potential and restoring membrane potential

36
Q

ECG changes in hyper K

A

Long PRI, peaked T waves, short QT, flattening of P wave, QRS widening and eventuall QRS degradation into sinusoidal pattern

37
Q

Three tx modalities for hyper K

A

Membrane stabilization
Intracellular shift of K+
Removal/excretion
All three sequentially in rapid succession as they have different onset and duration
Treat pH if acidy, if not acidy the shift won’t work as well

38
Q

Dougs that block renal excretion of K+

A

ACE inhibitors, Angio II receptor blockers, K+sparing diuretics and NSAIDS

39
Q

Magnesium

A

total body 24 grams or 2000 mEq

50-70% fixed in bone and only slowly exchangable, rest is mostly ICF (second most abundant intracellular cation)

40
Q

Normal Mg2+

A

1.5-2.5mEq/L

41
Q

Major causes of hypomagnesia

A

ETOH, malnutrition, cirrhosis, pancreatitis, excessive GI fluid losses
TX of DKA w/o mag (especially if malnourished) can cause this

42
Q

Hypomagnesia presentation

A

If normal calcium, hyperreflxia, tremor, tetany or convulsions

43
Q

Tetany

A

Intermittent muscular spasms

44
Q

Hyperalimentation

A

IV nutrients

45
Q

Chvostek sign

A

Hypocalcemia typically, but possible in respiratory alkalosis or hypomagnesemia
Tapping infront of tragus or at angle of jaw will illicit a facial spasm (stimulating facial nerve cause a facial nerve spasm)

46
Q

Trousseau sign

A

Flexion of the wrist and fingers after a BP cuff is inflated past systolic and remains there for 3 mins. Indicates hypocalcemia (sensitivity 94%) also could be hypomagnesia

47
Q

ECG changes in hypomagnesemia

A

Similar to hypokalemia and or hypocalcemia

Hypomagensemia may be secondary to hypoalbuminemia

Advanced medical (24 decks)

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