Lab Med - Electrolytes Flashcards
(95 cards)
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
What is important to avoid when doing blood draw for Potassium
hemolysis
| - will dump intracellular K+ into plasma, effect lab results
26
Hyperkalemia caused by:
- hemolysis, tissue damage, rhabdomyolysis
- acidosis
- renal failure
- ACEI
- BB
Others in slide but these are the ones Dr. McNeill said out loud
27
Hypokalemia cause by:
- low K+ intake (on Lasix for CHF, need K+ supplement to make up for what pee out)
- Diuretics
28
Two K+ sparing diuretics
- 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
Renal Tubular acidosis Type 1
- location
- acidemia?
- potassium status
- collecting tubules
- severe acidemia
- hypokalemia
30
Renal Tubular acidosis Type 2
- location
- acidemia?
- potassium status
- proximal tubule
- yes acidemia
- hypokalemia
31
Renal Tubular acidosis Type 4
- location
- acidemia?
- potassium status
- pathophys major organ
- Adrenal glands
- +/- mild acidemia
- hyperkalemia
32
Hypokalemia
- can cause (2)
- EKG changes
- neuromuscular and heart issues and ileus
| - depressed T wave and presence of U waves
33
Hyperkalemia
- can cause (1)
- EKG change
- neuromuscular and heart issues
| - peaked T waves in all leads
34
What is the basal body requirement for K+ per day
1-2 mEq/kg/day OR
| about 60-80 mEq/day
35
Hypokalemia tx
- 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
in general, how should the treatment of electrolyte disturbances proceed
SLOWLY, don't want to overdo it and push them into converse hypo/hyper state
37
If have EKG changes due to K+ imbalance, what sort of Tx is needed?
IV
38
If do NOT have EKG changes due to K+ imbalance, what sort of tx is needed
can correct more slowly with KCl tablets vs. IV
39
Hyperkalemia effects at
- 7-8 mEq/L
- 10 mEq/L
- v. fib in 5% of people
| - almost all people in v. fib
40
Hyperkalemia rapid tx
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
Hyperkalemia slow tx
- 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
Calcium
- normal range
- panic range
- NL: 8.5 - 10.5 mg/dL
- panic:
< 6.5 mg/dL
> 13.5 mg/dL
43
what causes about 60% of hypercalcemia?
parathyroid adenoma (benign)
44
What causes about 35% of hypercalcemia?
PTH-like secreting tumors
- breast, renal cell, prostate, lung cancers
- product PTH-RP (related protein)
- increases serum Ca+
45
Causes of hypercalcemia other than parathyroid adenoma (MC)
- 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
Causes of hypocalcemia
- hypoparathyroidism
- vitamin D deficiency
- renal insufficiency
- hypoalbuminemia
47
What must you also know to properly interpret Ca+ serum levels?
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
what three things regulate serum Ca
PTH
calcitriol
phosphorus
** there is a good picture of the system in the slides
49
where is calcitriol synthesized?
PCT
50
why hypocalcemia during renal failure?
Vitamin D is processed in the kidneys, need vitamin D to absorb Ca
51
Calcium effects on EKG
- Hypercalcemia: shortens ST and QT
| - hypocalcemia: prolonged ST and QT
52
Hypocalcemia symptoms
- all related to tetany
- Chvostek's sign (facial nerve twitch when rub)
- Trousseau's sign (Bp cuff on arm = fingers spasm)
53
Hypocalcemia treatment
- add calcium
- if IV (acute) tx, need ICU care
- if can tx more slowly, oral tx is fine
54
Hypercalcemia
```
Stones (renal, biliary)
Bones (bone pain)
Groans (abd pain, n/v)
Thrones (polyuria -> dehydration)
psychiatric overtones (depression, cog dysfunction, insomnia, coma)
```
55
Hypercalcemia treatment
- 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
Hypercalcemia causes
- need to investigate cause... not a dilution matter like Na+
- start with PTH
57
In hypercalcemia, what is expected PTH level
- low dt negative feedback
58
Hypercalcemia with high PTH
- primary hyperparathyroidism (60% of hypercalcemia)
| - PTH-rP from a tumor
59
hypercalcemia with low PTH
- 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
hypercalcemia caused by primary hyperparathyroidism - what are the two main causes
- benign adenoma
| - hyperplasia
61
What four types of cancer often cause PTHrP production
- breast
- lung (squamous cell)
- renal
- prostate
** native PTH will be low or zero in these cases
62
Chloride
| - range
98-107 mEq/L
63
What electrolyte issue is almost always seen with Cl issue?
Na bc NaCl is commonly how Cl is in body
| - treat the Na not the Cl
64
role of Cl
- principle anion of ECF
| - maintaining normal acid-base balance and osmolality
65
causes of hyperchloridemia
- renal failure
- nephrotic syndrome
- overtx with saline
- hyperparathyroidism
- diabetes insipidus
- diarrhea = metabolic acidosis
- respiratory alkalosis
** same that causes hypernatremia
66
cause of hypochloridemia
- 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
Anion gap equation
= Na - (Cl- + HCO3-)
| normal range 8-12 mmol/L
68
Acidosis with normal anion gap - two types
- diarrhea (MC)
| - Renal tubular acidosis
69
Acidosis with increased anion gap - two types list
- exogenous
| - endogenous
70
exogenous causes of acidosis with increased anion gap
- poisons like salicylate (ASA), old antifreeze
| - alcoholic ketoacidosis
71
endogenous causes of acidosis with increased anion gap
- DM ketoacidosis
| - uremia (elevated BUN)
72
how to workup acidosis
- ABG to determine if respiratory or not
| - then figure out anion gap
73
Alkalosis two types
- chloride responsive
| - chloride resistant
74
Chloride responsive alkalosis
- causes
- tx
- vomiting, NG suction
| - tx: replace Cl, easy :)
75
Chloride resistant alkalosis
- causes
- tx
- endocrine disorders: Conn's syndrome (hyperaldosteroneism), Barter's syndrome, Cushings
- tx: can't just add Cl, have to fix the endocrine disorder
76
Respiratory acidosis
- acute primary change
- arterial pH (ABG)
- K+
- anion gap
- sx
- pCO2 retention
- decrease in pH
- hyperkalemia
- normal anion gap
- dyspnea, rales, wheeze, respiratory outflow obstruction, etc.
77
Respiratory alkalosis
- acute primary change
- arterial pH (ABG)
- K+
- anion gap
- sx
- pCO2 depletion
- increase in pH
- hypokalemia
- normal or decreased anion gap
- anxiety, breathlessness, Chvostek, Trousseau
78
Metabolic acidosis
- acute primary change
- arterial pH (ABG)
- K+
- anion gap
- sx
- HCO3- depletion
- decrease in pH
- hyper or hypokalemia
- normal or increased anion gap
- weakness, air hunger, Kussmaul, dry skin and mucous membranes, etc.
79
Metabolic alkalosis
- acute primary change
- arterial pH (ABG)
- K+
- anion gap
- sx
- HCO3- retention
- increase in pH
- hypokalemia
- normal anion gap
- weakness, Chvostek, Trousseau
80
Three types of abnormal respiration to know for this exam
1. Biot's
2. Kussmaul
3. Cheyne-Stokes
81
Biot's respiration
- describe
- cause
- breath normally, blood well oxygenated
- apnea
- rapid breathing to re-oxgygenate
- repeat
- neurological damage (stroke)
82
Kussmaul respiration
- describe
- cause
- slow, deep breathing
- metabolic acidosis
- diabetic ketoacidosis
83
Cheyne-Stokes respirations
- crescendo/decrescendo
- apnea
- repeat
- neurological damage
84
Two main types of IV fluid
- crystalloids: contain a salt but no particulates
| - colloid: contain particulates, maybe also salts
85
Crystalloid fluids
- lactated ringers
| - normal saline +/- dextrose
86
what happens if give 1/2 or 1/4 normal saline solution
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
Colloids - 2 ex
- contain albumen
| - blood :)
88
Fluid management objectives (5)
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
Sequence to treat problems
- 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
How to calculate baseline fluid requirements for an adult
| - calculation
- 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
What is the K daily requirement
- 50-100 mEq/24hr but normal value is 60 mEq/24 hr
92
- what is normal rate of IV per hour
| - how many cc in a liter
- 125 cc/hour
| - 1000 cc in a liter
93
what is urine output goal for 24 hours
about 1 to 1.5 L (via foley)
| - min 60 cc per hour
94
what is urine output directly related to
- GFR which is directly related to cardiac output
95
what adjustment is made to IV if patient has a fever
add extra 100-150 cc/24hr of fluid per 1 degree C of fever
