Lab Med - Electrolytes Flashcards Preview

GU1 - Nephrology > Lab Med - Electrolytes > Flashcards

Flashcards in Lab Med - Electrolytes Deck (95)
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1
Q

BMP vs. CMP

A
  • about same cost
  • CMP is BMP + extras
  • unless looking for something specific like K+, might as well order CMP
  • BMP is Chem 7
  • CMP is chem 19 or 24
2
Q

What is included on BMP

A
  • glucose
  • BUN
  • Cr
  • BUN/CR ratio
  • serum Na+
  • serum K+
  • serum Cl-
  • CO2
  • calculated osmolality
3
Q

CO2 on BMP

A
  • reflection of bicarb in blood
  • venous measurement so not as accurate as ABG
  • ABG is a better way to measure for acid base balance
4
Q

Osmolality

  • NL value (ish)
  • what is it most helpful in determining
A
  • 300 mOsm/kg or so

- helpful in determining hydration status

5
Q

What is on CMP

A
  • all on BMP plus:
  • liver function
  • pancreatic function
  • Calcium
  • albumin

*not Mg, separate test

6
Q

Renin-angiotensin-aldosterone system

A

KNOW (but we know this, right??)

7
Q

What is important to remember about ACEI/ARB

A
  • all effect renin-angiotensin -aldosterone system
  • particularly elevate K+
  • must monitor K+ when pts take these meds
  • if already high end of normal K+, do not use these meds, if do, increases K+ even further…
8
Q

What lab tube is serum Na+ tested in?

A

marbled

9
Q

Na+

  • normal range
  • panic ranges
A

NL: 135-145 meq/L
panic:
<125 meq/L
>155 meq/L

10
Q

Na+ impact physiologically

A

neuromuscular function

11
Q

What is the first question you should ask when dealing with hypo- or hypernatremia?

A

what is the volume status of the patient?

12
Q

Hypervolemia sx

A
  • edema
  • rales
  • ascites
  • pleural effusion
  • SOB
  • CHF
  • cirrhosis
  • nephrosis
  • decreased urine/serum osmolality

*wet

13
Q

Hypovolemia sx

A
  • dry mucous membranes
  • dec. urine output
  • absense tears
  • delayed cap refill
  • hypotension
  • orthostatic hypotension
  • tachycardia
  • diuretic use
  • excessive sweating
  • v/d
14
Q

Euvolemia sx

A

none of the sx of hypo- or hypernatremia

15
Q

what volume status is related to hyponatremia

- example of condition this occurs in

A
  • hyponatremia: hypervolemia (dilution issue)

- seen in SIADH - too much ADH, don’t pee, become edematous and hyponatremic

16
Q

what volume status is related to hypernatremia

- 2 examples of when this occurs

A
  • hypernatremia: hypovolemia (too little volume, concentrated sodium)
  • diabetes insipidus: pee everything out
  • too much Lasix, summer in OKC = dehydration
17
Q

Value of:

  • hyponatremia
  • hypernatremia
A

<130 mEq/L

>150 mEq/L

18
Q

What are the SS of

  • hyponatremia
  • hypernatremia
A

they are the same!

  • lethargy, confusion, coma
  • muscle twitches, seizures, tetany
  • nausea, vom, Ileums (hypo)
  • pulm/peripheral edema (hyper)
19
Q

Hyponatremia

- what is MC cause

A

dilution issue (too much volume)

20
Q

How to treat hyponatremia dt dilution issue?

A
  • restrict fluids based on determination of

- ex: cut down calculated maintenance IV fluid by half for 24 hours and watch sodium (should rebound)

21
Q

Hypernatremia

- two causes

A
  • volume depletion (will have orthostatic hypotension)

- can also be euvolemic

22
Q

Treatment of volume depletion related hypernatremia

A
  • rehydrate with 0.9% physiologic saline until volume is restored

(if euvolemic tx with free water)

23
Q

Potassium

  • normal range
  • panic range
A

NL: 3.5-5.0
Panic:
<3
>6

24
Q

Potassium

  • physiologic effects when out of range
  • how regulated
A
  • profound effect on neuromuscular and cardiac function (very important to keep in NL range)
  • regulated by renal excretion
25
Q

What is important to avoid when doing blood draw for Potassium

A

hemolysis

- will dump intracellular K+ into plasma, effect lab results

26
Q

Hyperkalemia caused by:

A
  • hemolysis, tissue damage, rhabdomyolysis
  • acidosis
  • renal failure
  • ACEI
  • BB

Others in slide but these are the ones Dr. McNeill said out loud

27
Q

Hypokalemia cause by:

A
  • low K+ intake (on Lasix for CHF, need K+ supplement to make up for what pee out)
  • Diuretics
28
Q

Two K+ sparing diuretics

A
  • Spironolactone and triamterene

spironolactone used to treat:

  • acne (back acne) bc blocks testosterone which causes acne. works better in women
  • PCOS
  • premenstrual dysforic disorder
  • ascites (liver failure
29
Q

Renal Tubular acidosis Type 1

  • location
  • acidemia?
  • potassium status
A
  • collecting tubules
  • severe acidemia
  • hypokalemia
30
Q

Renal Tubular acidosis Type 2

  • location
  • acidemia?
  • potassium status
A
  • proximal tubule
  • yes acidemia
  • hypokalemia
31
Q

Renal Tubular acidosis Type 4

  • location
  • acidemia?
  • potassium status
  • pathophys major organ
A
  • Adrenal glands
  • +/- mild acidemia
  • hyperkalemia
32
Q

Hypokalemia

  • can cause (2)
  • EKG changes
A
  • neuromuscular and heart issues and ileus

- depressed T wave and presence of U waves

33
Q

Hyperkalemia

  • can cause (1)
  • EKG change
A
  • neuromuscular and heart issues

- peaked T waves in all leads

34
Q

What is the basal body requirement for K+ per day

A

1-2 mEq/kg/day OR

about 60-80 mEq/day

35
Q

Hypokalemia tx

A
  • give potassium!
  • IV with normal physiologic saline and add KCl to saline OR
  • oral KCl
  • go slow: good idea to correct first half of disturbance in first 8 hours, the other half in the remaining 16 hours
36
Q

in general, how should the treatment of electrolyte disturbances proceed

A

SLOWLY, don’t want to overdo it and push them into converse hypo/hyper state

37
Q

If have EKG changes due to K+ imbalance, what sort of Tx is needed?

A

IV

38
Q

If do NOT have EKG changes due to K+ imbalance, what sort of tx is needed

A

can correct more slowly with KCl tablets vs. IV

39
Q

Hyperkalemia effects at

  • 7-8 mEq/L
  • 10 mEq/L
A
  • v. fib in 5% of people

- almost all people in v. fib

40
Q

Hyperkalemia rapid tx

A
  1. protect myocardium: flood system with CaCl
  2. alkalize the blood with sodium bicarbonate- shifts K+ into cell
  3. Ampule of dextrose 50g followed by insulin bolus (10U) or regular fast acting insulin, insulin will shift K into cell
  4. Albuterol inhaler: sympathomimetic, shifts K+ into cell

*peaked t waves corrected quickly

41
Q

Hyperkalemia slow tx

A
  • polystyrene - drink or enema, binds K+ in GI and prevents its absorption
  • 20-40 mg Lasix via IV, have them pee out the K+
42
Q

Calcium

  • normal range
  • panic range
A
  • NL: 8.5 - 10.5 mg/dL
  • panic:
    < 6.5 mg/dL
    > 13.5 mg/dL
43
Q

what causes about 60% of hypercalcemia?

A

parathyroid adenoma (benign)

44
Q

What causes about 35% of hypercalcemia?

A

PTH-like secreting tumors

  • breast, renal cell, prostate, lung cancers
  • product PTH-RP (related protein)
  • increases serum Ca+
45
Q

Causes of hypercalcemia other than parathyroid adenoma (MC)

A
  • intake of too much milk (or vitamin D)
  • Paget’s dz: overactive digestion and laying down of bone in an abnormal pattern. Release of lots of bone Ca+
  • Antacids (calcium carbonate): over consumption
  • Lithium (bipolar tx)
  • PTH-like secreting tumors
46
Q

Causes of hypocalcemia

A
  • hypoparathyroidism
  • vitamin D deficiency
  • renal insufficiency
  • hypoalbuminemia
47
Q

What must you also know to properly interpret Ca+ serum levels?

A

albumin

for every decrease in albumin by 1 mg/dL, must increase Ca by 0.8 mg/dL.

*if albumin decreased from 4 to 1: (3)(0.8) = 2.4 + calcium level on lab = adjusted calcium level

48
Q

what three things regulate serum Ca

A

PTH
calcitriol
phosphorus

** there is a good picture of the system in the slides

49
Q

where is calcitriol synthesized?

A

PCT

50
Q

why hypocalcemia during renal failure?

A

Vitamin D is processed in the kidneys, need vitamin D to absorb Ca

51
Q

Calcium effects on EKG

A
  • Hypercalcemia: shortens ST and QT

- hypocalcemia: prolonged ST and QT

52
Q

Hypocalcemia symptoms

A
  • all related to tetany
  • Chvostek’s sign (facial nerve twitch when rub)
  • Trousseau’s sign (Bp cuff on arm = fingers spasm)
53
Q

Hypocalcemia treatment

A
  • add calcium
  • if IV (acute) tx, need ICU care
  • if can tx more slowly, oral tx is fine
54
Q

Hypercalcemia

A
Stones (renal, biliary)
Bones (bone pain)
Groans (abd pain, n/v)
Thrones (polyuria -> dehydration)
psychiatric overtones (depression, cog dysfunction, insomnia, coma)
55
Q

Hypercalcemia treatment

A
  • saline diuresis: load up with normal saline IV and Lasix - will pee the calcium right out
  • same as other electrolytes, slowly adjust to avoid hypocalcemia
56
Q

Hypercalcemia causes

A
  • need to investigate cause… not a dilution matter like Na+
  • start with PTH
57
Q

In hypercalcemia, what is expected PTH level

A
  • low dt negative feedback
58
Q

Hypercalcemia with high PTH

A
  • primary hyperparathyroidism (60% of hypercalcemia)

- PTH-rP from a tumor

59
Q

hypercalcemia with low PTH

A
  • next step is bone survey/scan
  • if not a malignancy, then check serum vitamin D
  • Dr. McNeill did not go over the list specifically but there are multiple causes on the chart in the slides
60
Q

hypercalcemia caused by primary hyperparathyroidism - what are the two main causes

A
  • benign adenoma

- hyperplasia

61
Q

What four types of cancer often cause PTHrP production

A
  • breast
  • lung (squamous cell)
  • renal
  • prostate

** native PTH will be low or zero in these cases

62
Q

Chloride

- range

A

98-107 mEq/L

63
Q

What electrolyte issue is almost always seen with Cl issue?

A

Na bc NaCl is commonly how Cl is in body

- treat the Na not the Cl

64
Q

role of Cl

A
  • principle anion of ECF

- maintaining normal acid-base balance and osmolality

65
Q

causes of hyperchloridemia

A
  • renal failure
  • nephrotic syndrome
  • overtx with saline
  • hyperparathyroidism
  • diabetes insipidus
  • diarrhea = metabolic acidosis
  • respiratory alkalosis

** same that causes hypernatremia

66
Q

cause of hypochloridemia

A
  • vomiting (will NOT cause hyponatremia bc vomit HCl, no Na)
  • diarrhea
  • GI suction
  • renal failure with salt deprivation
  • diuretics
  • chronic resp. acidosis
  • diabetic ketoacidosis
  • excessive sweating
  • SIADH
    many more
67
Q

Anion gap equation

A

= Na - (Cl- + HCO3-)

normal range 8-12 mmol/L

68
Q

Acidosis with normal anion gap - two types

A
  • diarrhea (MC)

- Renal tubular acidosis

69
Q

Acidosis with increased anion gap - two types list

A
  • exogenous

- endogenous

70
Q

exogenous causes of acidosis with increased anion gap

A
  • poisons like salicylate (ASA), old antifreeze

- alcoholic ketoacidosis

71
Q

endogenous causes of acidosis with increased anion gap

A
  • DM ketoacidosis

- uremia (elevated BUN)

72
Q

how to workup acidosis

A
  • ABG to determine if respiratory or not

- then figure out anion gap

73
Q

Alkalosis two types

A
  • chloride responsive

- chloride resistant

74
Q

Chloride responsive alkalosis

  • causes
  • tx
A
  • vomiting, NG suction

- tx: replace Cl, easy :)

75
Q

Chloride resistant alkalosis

  • causes
  • tx
A
  • endocrine disorders: Conn’s syndrome (hyperaldosteroneism), Barter’s syndrome, Cushings
  • tx: can’t just add Cl, have to fix the endocrine disorder
76
Q

Respiratory acidosis

  • acute primary change
  • arterial pH (ABG)
  • K+
  • anion gap
  • sx
A
  • pCO2 retention
  • decrease in pH
  • hyperkalemia
  • normal anion gap
  • dyspnea, rales, wheeze, respiratory outflow obstruction, etc.
77
Q

Respiratory alkalosis

  • acute primary change
  • arterial pH (ABG)
  • K+
  • anion gap
  • sx
A
  • pCO2 depletion
  • increase in pH
  • hypokalemia
  • normal or decreased anion gap
  • anxiety, breathlessness, Chvostek, Trousseau
78
Q

Metabolic acidosis

  • acute primary change
  • arterial pH (ABG)
  • K+
  • anion gap
  • sx
A
  • HCO3- depletion
  • decrease in pH
  • hyper or hypokalemia
  • normal or increased anion gap
  • weakness, air hunger, Kussmaul, dry skin and mucous membranes, etc.
79
Q

Metabolic alkalosis

  • acute primary change
  • arterial pH (ABG)
  • K+
  • anion gap
  • sx
A
  • HCO3- retention
  • increase in pH
  • hypokalemia
  • normal anion gap
  • weakness, Chvostek, Trousseau
80
Q

Three types of abnormal respiration to know for this exam

A
  1. Biot’s
  2. Kussmaul
  3. Cheyne-Stokes
81
Q

Biot’s respiration

  • describe
  • cause
A
  • breath normally, blood well oxygenated
  • apnea
  • rapid breathing to re-oxgygenate
  • repeat
  • neurological damage (stroke)
82
Q

Kussmaul respiration

  • describe
  • cause
A
  • slow, deep breathing
  • metabolic acidosis
  • diabetic ketoacidosis
83
Q

Cheyne-Stokes respirations

A
  • crescendo/decrescendo
  • apnea
  • repeat
  • neurological damage
84
Q

Two main types of IV fluid

A
  • crystalloids: contain a salt but no particulates

- colloid: contain particulates, maybe also salts

85
Q

Crystalloid fluids

A
  • lactated ringers

- normal saline +/- dextrose

86
Q

what happens if give 1/2 or 1/4 normal saline solution

A

dilute the physiologic saline, ok to do with reasonable kidney function but make sure don’t give too much free fluid without salt
*straight water IV needs to be in ICU

87
Q

Colloids - 2 ex

A
  • contain albumen

- blood :)

88
Q

Fluid management objectives (5)

A
  1. treat the person not the lab value
  2. treat abnormalities at the approx rate they occured
  3. multiple problems should be treated in a sequence (next card)
  4. acidosis is related to elevations in K, Ca, Mg and alkalosis is opposite
  5. sx less severe if ALL electrolytes are low vs. just one
89
Q

Sequence to treat problems

A
  • fluid volume and perfusion deficits
  • pH
  • K, Ca, Mg
  • Na, Cl

*when fluid and perfusion deficits are fixed, often pH and electrolytes will correct themselves

90
Q

How to calculate baseline fluid requirements for an adult

- calculation

A
  • first 10 kg = 100 ml/kg/24 hr
  • second 10 kg = 50 ml/kg/24 hr
  • weight > 20 kg = 20 ml/kg/24 hr
91
Q

What is the K daily requirement

A
  • 50-100 mEq/24hr but normal value is 60 mEq/24 hr
92
Q
  • what is normal rate of IV per hour

- how many cc in a liter

A
  • 125 cc/hour

- 1000 cc in a liter

93
Q

what is urine output goal for 24 hours

A

about 1 to 1.5 L (via foley)

- min 60 cc per hour

94
Q

what is urine output directly related to

A
  • GFR which is directly related to cardiac output
95
Q

what adjustment is made to IV if patient has a fever

A

add extra 100-150 cc/24hr of fluid per 1 degree C of fever