Electrolyte Abnormalities Flashcards

1
Q

Hyponatremia is defined by a serum Na of what?

A

Serum Na <135

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2
Q

Hyponatremia is very common especially in which popultions?

A

hospitalized, ICU patients

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3
Q

ADH is released in response two which two stimuli?

A

Osmotic stimuli from increases in serum osmolarity detected by osmoreceptors in the anterior hypothalamus

non-osmotic stimuli from decreases in BP or BV detected by aterial baroreceptors

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4
Q

What are some other non-osmotic stimuli for ADH release?

A

Baroreceptors

Nausea

Hypoxia

Pain

Medications

Pregnancy

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5
Q

Hyponatremia results primarily from increases in what?

A

increases in TBW, not changes in sodium

(can be from increase in fluid intake or decrease in water excretion)

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6
Q

What are the clinical manifestations of hyponatremia?

A

depends on severity and acuity, most asymptomatic until levels are <125

  • headache
  • fatigie
  • dizziness
  • nausea
  • seizures
  • cerebral edema
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7
Q

What is necessary when working up hyponatremia to minimize confusion on the underlying etiology?

A

a systematic approach

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8
Q

Acute hyponatremia is a low Na level for how long?

A

<48hours

chronic >48hrs or unknown duration

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9
Q

What are the two steps of approaching hyponatremia?

A
  1. measure serum osmlarity to determine if hypotonic, isotonic or hypertonic hyponatremia is present
  2. if hypotonic hyponatremia is present, then assess volume status by measuring random urine Na and urine osmolarity
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10
Q

When assessing for hyponatremia, it is important that all labs be drawn (apart or simultaneously?)

A

simultaneously

best to avoid treatment until labs are drawn

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11
Q

What are some exam findings indicative of hypovolemia?

A

hypotension

orthostatic VS +

tachycardia

poor cap refill

dry mucosa

flat JV

decreased urine output

>50% collapse of IVC during echo

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12
Q

What are some exam findings of hypervolemia?

A

hypertension

sacral or LE edema

JVD

dilated IVC on echo

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13
Q

What is a diagnosis of exclusion after ruling out cortisol deficiency, hypothyroidism and other causes?

What is the most common malignancy associated with this?

A

SIADH

Small cell lung cancer

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14
Q

What drugs are associated with SIADH?

A

antidepressents

anti convulsants

antipsychotics

cyclophosphamide

opiates

MDMA

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15
Q

What presents as a true hyponatremia with euvolemia and urine osm > 300?

A

SIADH

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16
Q

How to treat acute hyponatremia?

A

can have rapid correction of Na with little risk of ODS

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17
Q

how is chronic hyponatremia treated?

A

careful of rapid correction as pt is at higher risk of ODS

goal is to raise serum Na by 8-10mEq/day with no more than 18mEq/L within the first 48hrs

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18
Q

For symptomatic hyponatremic patients give what to raise Na quickly (acute setting)?

A

Give hypertonic saline 3% solution

(raise it to 3-4 mEq/L to stop symptoms and then slowly raise back to normal)

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19
Q

If Na is correcting too quickly, how can you lower it back to acceptable level to avoid ODS?

A

D5W

DDAAVP

d/c some therapies that may be raising Na too fast

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20
Q

Besides hypertonic saline for SIADH, what else is used in treatment?

A

Water restriction

Furosemide

Salt/urea tablets

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21
Q

What are four severe complications of hyponatremia?

A

Seizures

coma

Death from uncal herniation

ODS

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22
Q

What is Osmotic Demyelination Syndrome?

A

ODS is delayed 2-6 days after rapid Na correction

Demyelination occurs in the pontine/extrapontine nucleus

can cause Locked-in syndrome

Diagnose via MRI, may take 4 weeks to show up

alcoholics are at high risk for this

23
Q

Hypernatremia, often seen in infants and elderly, is defined as a serum Na of

Risk factors include:

A

>145

Trauma, burns, ICU patients, dementia, uncontrolled DM

24
Q

What are the two underlying processes that lead to hypernatremia?

A

unreplaced water loss (fancy for dehydration)

-common in elderly due to impaired thirst mechanism

Sodium overload

25
Q

What are the clinical manifestations of hypernatremia?

A

results in cell shrinkage as water moves out of cel into ECF

causes irritability, AMS, lethargy, seizures, hyperreflexia, ICH

acute-<48hrs

chronic->48hours or unknonw duration

26
Q

While acute hypernatremia can be corrected with little risk, correcting chronic hypernatremia too rapidly can lead to ?

What are the two steps of correction?

A

cerebral edema

goal is to lower serum sodium by 10-12mEq/day

  1. replace water deficit
  2. correct underlying cause leading to water loss
27
Q

Excess K is removed from the body by which organ?

A

Mostly via the kidneys with some loss in the feces

Kidneys are primary regulator of K

28
Q

Which part of the kidney regulates K secretion?

A

The distal part of the nephron

principal cells for secretion

a-intercalated cells for reabsorption

29
Q

Serum K is regulated very closely, thus any small alteration in K can have what?

A

serious major clinical manifesations

30
Q

Hyperkalemia is defined as serum K of

A

>5.0 or 5.5meq/L

affects up to 10% of hospitalized pts

31
Q

high serum K can cause which cardiac complications?

A

V Fib

Bradycardia from AV block

Asystole

32
Q

Hyperkalemia can also decrease ammioniogenesis and decrease NH4Cl excretion leading to what?

A

less net acid excretion and metabolic acidosis

33
Q

high K concentration makes the membrane potential (more or less) negative?

A

less negative

34
Q

A sinusoidal wave pattern seen on EKG correlates with which electrolyte abnormality?

A

Hyperkalemia (>9) and V Fib

35
Q

What are the two main reasons for hyperkalemia?

A

Transcellular shift

Decreased renal K excretion

36
Q

Transcellular shift leading to hyperkalemia can be from which causes?

A

Pseydhyperkalemia

Metabolic acidosis

insulin deficiency, hyperglycemia and hyperosmolality

increased tissue catabolism

meds

exercise

blood transfusion

37
Q

What causes Pseudohyperkalemia

A

RBC hemolysis uring venipuncture

clotted blood samples (check plasma to rule out)

Leukocytosis

38
Q

What are the causes of decreased ranl K excretion?

A

Low aldosterone secretion

Aldosterone resistance

AKI/CKD

39
Q

A fractional excretion of K <10% indicates

A fractional excretion of K >10% indicates

A

renal etiology of hyperkalemia

extrarenal etiology of hyperkalemia

40
Q

If peaked T waves are seen on EKG due to hyperkalemia, give what drug to stabilize cardiac membrane?

A

calcium gluconate

41
Q

For transcellular shift leading to hyperkalemia, give which drugs?

A

insulin or dextrose

B2 agonist

42
Q

to remove excess K, give which drugs?

A

Sodium Polystyrene sulfonate

Zirconium cycloslicate

Patiromer

43
Q

What are two general modifications to treat hyperkalemia regardless of cause?

A

low K diet

d/c meds that increase K (ACEI, ARB, Ald blockers, K supplements)

44
Q

Hypokalemia is defined as a serum K of

A

<3.5 mEq/L

affects up to 20% of hospitalized patients and is less common in outpatients

45
Q

What are some cardiac complications associated with hypokalemia?

A

PACs

PVCs

tachycardia/bradycardia

V. fib

46
Q

What are some muscular complications of hypokalemia?

A

skeletal muscle weakness (diaphragm)

rhabdomolysis

47
Q

Hypokalemia is associated with which acid-base disturbance?

What does low K do to the membrane potential?

A

metabolic alkalosis

low K makes the membrane potential more negative

48
Q

What are the three main reasons for hypokalemia?

A
  1. transcellular shift
  2. extrarenal loss
  3. renal loss
49
Q

What are some causes of transcellular shift leading to hypokalemia?

A

Insulin

B2 agonist

Metabolic alkalosis

50
Q

What are the most common causes of extrarenal loss leading to hypokalemia?

A

GI loss via vomiting, NG suctinoing, diarrhea

Cutaneous loss via sweating

51
Q

What are the causes of renal loss leading to hypokalemia?

A

diuretics

increased mineralocorticoid activity (1’ hyperaldosteronism, Cushing syndrom)

hypomagnesemia

52
Q

What are the urine labs to order to diagnose hypokalemia?

A

24hr urine K (nest method for assessing renal K excretion)

Urine K/Cr ratio

53
Q

how should hypokalemia be treated?

A

treat underlying cause

give KCl

K will increase by 0.1 units for every 10 units of KCl given

replace Mg if low