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Foundations II- Nephrology > Electrolytes > Flashcards

Electrolytes Flashcards

1
Q

What regulates serum sodium?

A

thirst

ADH

RAAS system

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2
Q

What’s included on an electrolyte panel?

A 
Na 
K 
Cl 
CO2
Ca

*Mg and phosphate need to be ordered separately

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3
Q

What is the most common electrolytes abn. in hospitalized pt?

A

hyponatremia

danger zone Na below 125

can be acute or chronic

can be seen in assoc. with pulmonary disease of CNS disorder

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4
Q

What are some clinical manifestations of hyponatremia?

A 
Headache, dizziness
Nausea, vomiting
Lethargy
Weakness
Confusion 
Hypoventilation, respiratory arrest
Seizures
Coma
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5
Q

What are some causes for hyponatremia?

A

Pseudohyponatremia
Redistributive hyponatremia

Hypovolemic hyponatermia
Hypervolemic hyponatremia
Euvolemic hyponatremia

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6
Q

What is pseudohyponatremia?

A

Falsely low serum sodium

Serum Na<135 but NORMAL osmolality

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7
Q

When does pseduohyponatremia occur?

A

Occurs with hyperlipidemia and hyperproteinemia

-Can also occur with obstructive jaundice & multiple myeloma

lab artifact!! call lab to confirm

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8
Q

What is redistributive hyponatremia?

A

Hyperosmolar state; “relative hyponatremia”

Caused by osmotically active solutes in extracellular space that draw H2O from cell diluting

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9
Q

What is a common cause of redistributive hyponatremia?

A

hyperglycemia

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10
Q

How do you calculate redistributive hyponatremia?

A

Add 1.5mEq/L to sodium value for every 100mg/dl serum glucose > 100mg/dl

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11
Q

What are some renal losses responsible for Hypovolemic Hyponatremia?

A

diuretics

osmotic diuresis

addison’s disease

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12
Q

What are some non-renal losses responsible for Hypovolemic Hyponatremia?

A

External GI: vomiting, diarrhea, NG suction, fistula
Internal GI: pancreatitis, peritonitis
Burns

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13
Q

Tx for hypovolemic hyponatremia?

A

replace fluid losses (with isotonic fluid, ie. NS), and treat the underlying cause

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14
Q

Causes for hypervolemic hyponatremia? tx?

A

Hepatic cirrhosis, CHF, Renal failure

diuretics, dialysis, fluid restriction

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15
Q

Causes for euvolemic hyponatremia?

A

SIADH

Primary polydipsia
Often psychogenic
Urine maximally dilute

Hypothyroidism

Adrenal Insufficiency

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16
Q

Tx for euvolemic hyponatremia?

A

fluid restriction,

treat underlying cause.

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17
Q

Describe SIADH

A

Syndrome of Inappropriate Antidiuretic Hormone Secretion

This impairs free water excretion but sodium continues to be excreted normally

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18
Q

Hallmark findings in SIADH?

A

Concentrated urine (>100mOsm/kg) with low serum osmolality and euvolemia

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19
Q

SIADH usually occurs in…

A

hospital setting

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20
Q

Tx for SIADH?

A

Fluid restriction

Treatment of underlying pathology

For refractory cases +/-
Hypertonic saline
Demeclocycline
Urea
Lithium
“Vaptans”
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21
Q

How do we eval for hyponatremia?

A

good H &P

labs: UA- Na and osmolarity, serum osmolarity, CMP

secondary labs: TSH, serum cortisol

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22
Q

Tx for hyponatremia?

A

Depends on underlying cause

If Na<125 or symptomatic hospitalize!

Chronic hyponatremia must be managed with extreme care
-slow cautious correction

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23
Q

Why do we need to be careful about correcting Na?

A

Rapid increase in serum sodium can lead to cerebral pontine myelinolysis (CPM)

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24
Q

What can be used to tx hyponatremia?

A

hypertonic solutions

traditional tx: chronic hyponatremia =demeclocycline

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25
How often should you check serum Na while correcting?
q2hrs
26
What is Central pontine myelinolysis?
CPM is a poorly understood entity characterized by focal demyelination in the pons and extra- pontine areas – it is irreversible!!
27
Sxs of central pontine myelinolysis?
Dysarthria, dysphagia, seizures, altered mental status, quadriparesis, hypotension
28
Work up for hyponatremia?
Check serum osmolarity - if high >> hyperglycemia - if low >> check urine osmolarity if urine osmolarity is low >> water intoxication if high >>need to check volume status
29
What is hypernatremia?
A hypertonic disorder due to serum sodium >145mEq/L | “Too little water relative to salt”
30
Clinical features of hypernatremia?
``` Often asymptomatic Thirst, signs of volume depletion AMS, weakness Neuromuscular irritability Focal neurologic deficits Seizures or coma ```
31
Causes for hypernatremia?
Too little dietary water Too much dietary salt Excessive water loss from the body
32
Work up for hypernatremia?
check urine osmolality! if less than plasma osmolality (<300) = central or nephrogenic DI If intermediate (300-600) = osmotic diuresis or DI If high (>600) : dehydration most likely secondary to extrarenal water loss
33
Normal response to hypernatremia?
thirst, increase fluid intake concentrates urine
34
What is diabetes insipidus?
Nonosmotic urinary water loss in setting of elevated serum sodium: urine is dilute when it should be concentrated
35
Describe central DI
due to impaired secretion of antidiuretic hormone (ADH)
36
Describe Nephrogenic DI
lack of kidney response to ADH, causing continued water loss even though patient is low on water. Adequate ADH is present.
37
Tx for nephrogenic DI?
Thiazide diuretic Amiloride (potassium sparing diuretic) Chlorpropamide (antidiabetic oral agent) NSAIDs have been tried (including Indomethacin)
38
Tx for hypernatremia?
hospitalize if severe stop water loss replace water deficit -but not too quickly!
39
How can you calculate water deficit? What is this used for?
normal TBW-Current TBW Normal: .6 x body weight in kg current: normal serum x normal TBW to replace free water in hypernatremia
40
Serum Potassium is a...
major IC cation
41
hypokalemia is common in...
pts receiving diuretics
42
Clinical presentation of hypokalemia?
``` Weakness, fatigue Muscle cramps Hyporeflexia Flaccid paralysis (ascending) Cardiac arrhythmia Hypercapnia ```
43
ECG findings for hypokalemia?
Flattened T waves Prominent U waves Premature Ventricular Contractions (PVC’s) Depressed ST segments
44
What are the 3 dif. mechanisms that can causes hypokalemia?
transcellular shifts- drugs, delirium tremens... renal losses - diuretics MC cause extra-renal losses- V/D, burns, Mg deficiency
45
Tx for hypokalemia?
replace K (oral preferred!) and underlying cause telemetry monitoring if inpt IV for those not able to eat/emergencies
46
Can you push IV K?
NO, should be given slowly give with lido if using peripheral IV
47
How do you replace K?
For every 0.1 mEq/L below 4mEq/L, Give 10 mEq/L (10 for ever .1 you want to increase)
48
What is hyperkalemia?
Defined as K > 5 mEq/L, severe > 6.5 mEq/L | In the absence of renal failure or other identifiable cause, actually quite rare
49
Clinical presentation for hyperkalemia?
Relatively asymptomatic Muscle weakness Begins in legs and ascends to trunk and arms “ascending flaccid paralysis” ECG changes: potentially life threatening arrhythmias
50
ECG findings in hyperkalemia?
Peaked T waves > widen QRS > junctional rhythm> ventricular fibrillation K > 6 more likely to cause severe cardiac arrhythmias
51
Causes of hyperkalemia?
Factitious-hemolysis Impaired K excretion- renal failure Drugs- K sparing diuretics, ACE/ARBs,NSAIDS, Bactrim Increased intake
52
Other causes for hyperkalemia?
conditions which move K+ from intracellular to extracellular space: -tissue damage, acidosis, decreased insulin
53
Tx for emergent hyperkalemia?
1. IV calcium 2. Maneuvers to shift K from ECF to ICF - -sodium bicarb - -Insulin IV + D50W 3. other potential options: nebulized albuterol, IV lasix, dialysis
54
Less urgent tx for hyperkalemia?
Kayexalate - exchanges Na for K in the gut - causes lots of diarrhea Lasix correct underlying cause
55
How is serum calcium measured?
otal Ca = free (ionized) + protein-bound Used to evaluate metabolism and monitor patients with hyperparathyroidism, malignancies and renal failure
56
There is an inverse relationship btwn Ca and...
phosphate
57
Most Ca is in the...
bone
58
What are the dif. Ca forms?
ionized complexed protein-bound (albumin)
59
A decreased in serum Ca triggers the release of.... A increase in serum Ca triggers the release of...
PTH from parathyroid gland, which acts to increase Ca in the blood by: calcitonin from the thyroid gland, which acts to decrease Ca in blood by: Inhibiting bone resorption
60
hypercalcemia..
Calcium > 10.1 | Relatively common, most cases are mild and self-limiting
61
presentation for hypercalcemia?
Stones, Bones, Abdominal Moans, | and Psychiatric Groans”
62
Primary causes for hypercalcemia?
malignancy and hyperparathyroidism other causes: meds
63
What labs should you check for hypercalcemia?
Serum Ca PTH and rPTH TSH Protein electrophoresis
64
Tx for hypercalcemia?
***volume expansion - Calcitonin > lowers levels rapidly - Pamidronate - Zoleronic Acid Others: fallium nitrate, prednisone, dialysis
65
Presentation for hypocalcemia?
``` Increased neuromuscular: excitability (tetany) Paresthesias (peri-oral, extremities) Hyperactive reflexes, carpopedal spasms Chvostek’s sign Trousseau’s sign ``` Cardiovascular effects: ECG changes (prolonged QT interval); arrhythmia Hypotension
66
What is tetany?
involuntary sustained contractions
67
Chvostek's sign?
tapping facial nerve against the bone just anterior to the ear results in contraction of facial muscles
68
Trousseau's sign?
occluding brachial artery for 3 minutes with BP cuff induces carpal spasms.
69
Causes for hypocalcemia?
hypoalbuminemia, large blood tranfusion, hypomagnesemia, hypoparathyroidism, renal failure, intestinal malabsorption/Vit D def.
70
Neuromuscular changes in hyper v. hypocalcemia
decreased excitability (weakness) increases excitability (tetany)
71
Phosphate
used to investigate parathyroid and calcium abnormalities
72
Causes for hyperphosphatemia
``` Renal failure Hypoparathyroidism Hypocalcaemia Rhabdomyolysis Exogenous Phosphorus ```
73
causes for hypophosphatemia?
``` Decreased intestinal absorption Hyperparathyroidism Chronic alcoholism Severe diarrhea Cellular shift -Insulin -Refeeding Syndrome ```
74
Describe Mg
Normal value: 1.3 – 2.1 mEq/L (adult) Involved in neuromuscular and cardiac function bound to ATP, excreted by kidneys
75
Mg is intimately tied to...
Ca and K
76
Hypomagnesium inhibits... and impairs...
PTH activity which can cause hypocalcemia and impairs ability of the kidneys to conserve K

Foundations II- Nephrology (7 decks)

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