Electrolytes & BUN Flashcards
what are the lab values which are included in an BMP
- sodium (Na)
- potassium (K)
- chloride (Cl)
- CO2
- BUN (blood urea nitrogen)
- creatitine (Cr)
- glucose
also…
- Anion gap
- calcium (Ca)
what is the role of sodium within the body
- major role in regulated blood pressure
- muscle and nerve function are also regulated by sodium contents
- sodium is the MAJOR extracellular cation (+)
- controls fluid volume becuase wherever sodium goes, water follows (thus BP control)
- excreted by the kidneys (therefore, poor kidney function can elevate potassium levels)
- excreted through sweat too (to a lesser extent)
what is the role of potassium within the body
- controls muscle and nerve impulses at the level of thresholds and channels
- the MAJOR INTRAcellular cation (+)
- excreted mainly by the kidneys
- minial excreting through sweat and GI losses (diarrhea, vomiting)
what is the role of chloride in the body
- chloride maintains acid-base balances
- maintains nerve impulses
- maintains fluid balance
- maintains stomach acid
- excreted within the urin
- a MAJOR EXTRAcellular anion (-)
what is the role of carbon dioxide in the body
- it serves as an indirect role to measure bicarb
- excreted via the lungs
- involved in pH regulation, repiratory drive, and helps Hgb attract O2
Signs and Symptoms of Hyponatremia
- what are the earlier signs: at what Na level?
- what are some later signs: at what Na level?
at a Na < 130
- nausea: becuase of cerebral edema: with less salt outside the cells: there is less pull of fluid out; thus more flow into cells creating the feeling of nausea
- malaise
at a Na < 120
- headache
- lethargy
- obtundation
- seizure
- coma
- respiratroy arrest
other symptoms of hyponatremia
- asymptomatic
- fatigue
- nausea
- dissiness
- gait abnormalities
- forgetfulness
- confusion
- muscle cramps
- lethargy
seizure & coma: acute exacerbations
are some questions you need to ask to evaluate your pt and their hyponatremia?
decide if the patient is also hyperglycemic?
- if hyperglycemic: correct sodium via (measured sodium + 1.6(glucose-100)/100)
are they post-op (especially GU) ?
have they been given mannitol, glycerol or IV immunoglobulin?
do they have…
- elevated lipemic serum
- jaundice
- plasma cell dyscrasia
want to assess if they are isotonic or hypertonic hyponatremia
what are some causes of hypotonic hyponatremia
think high levels of fluid volume: diuluting the sodium and other solutes
- polydipsia
- low dietary intake of sodium
- advanced renal impairment
- diuretic -induced hyponatremia
- volume depleltion (hypovolemic)
- heart failure/cirrhosis (hypervolemic, but low sodium)
- SIADH
- CNS abnormality
- drugs
- malignancy
- hormonal deficiency
- exercise induced (marathon!)
drugs: antidepressants, anti seizures, antipsychotis, anticancer, antidiabetes, vasopressin-like
Diagnostics to do for hyponatremia
- BMP
- LFTs: AST,ALT, bilirubin, albumin
- serum osmolality : gives idea of what solutes are in the blood at what concentration
- urine sodium : determines if the cause of the hyponatermia is due to renal or extrarenal causes (renal we will see hypovolemic hyponatermia with a high level or urine sodium, extra-renal will see low levels of sodium in the urine)
- urine osmolality : the amount of solutes within the urine
repeat urine osm and sodium after adequate sodium is given via IV will help determine if its a volume issue or a thyroid and signally issue
Treatment of hyponatremia
what happens if you correct too quickly?
what is our goal sodium
goal is to correct the sodium level = increasing sodium level by 1mEq/L/hr
- fluid restriction
- sodium tablets
in general: avoid correcting the sodium level too quicky: this could cause flash pulmonary edema or osmotic demyelination syndrome
in acute hyponatermia you can give IV saline 3% to rise the sodium level by 5mEq/L
Goal Sodium : 130
treat underlying cause!
Signs and Symptoms of Hypernatremia
plasma serum concentration > 145 mEq/L
- thrist
- lethargy
- irritability
- fever
- urinary symptoms (oligouria, polyuria, nocturia)
- twitching
- confusion
- seizures
- hyperreflexia
- coma
as the sodium concentration increases in the serum; fluid is drawn out of the cells; they shirnk and produce the seen symptoms (especially within the brain
Hypernatremia
- diagnosis
- acurate history
- BMP
- Urine Osmolality (should be over 600)
normal 500-800
a decreased urine osmolality & plasma = central or nephrogenic diabetes insipudus (becuase so much fluid is being lost form the serum, high sodium in the serum)
an increase urine osmolality 600 (normal) = think of extrarenal losses of water (GI losses common if the urine sodium is < 25)
major causes of hypernatremia
- inappropriate water consumption; and sweat loss
- GI losses
- central or nephrogenic diabetes insipidus ( no response of the body to uptake water leds to increased water loss thus more sodium per water)
- osmotic diuresis (glucose, urea, mannitol)
- CNS dysfunction
- sodium overload (in the hospital!!)
Treatment of hypernatremia
Acute (< 48 hours)
- sodium posioning risk, diabetes insipidus or severe hyperglycemia (because of the osmostic diuresis that occurs with hyperglycemia)
give 5% dextrose in water IV because adding glucose into the body helps the osmostic pressure to pull fluid back into the body and balance out the sodium
- do at a faster rate: 3-6mL/kg/hr
Chronic ( > 48 hours) most common
- 5% dextrose in water IV
- do at 1.35mL/height x kg
Clinical Manifestations of Hypercalcemia
renal signs
- poyluria
- polydipsia
- nepthrocalcinosis
- nephrogenic DI
- acute & chronic renal insufficiency
GI signs
- anorexia
- N/V
- constipation
- pancreatitis
- peptic ulcer disease
MSK
- muscle weakness
- bone pain
- decreased bone density
Neuro
- inability to concentrate
- fatigue
- coma
- confusion
Cardiac
- shortened QT interval
- bradycardia
- HTN
What are some reasons for hypercalcemia
parathyroid mediated processes
- MEN syndrome
- familial or primary hyperparathyroidism
non-parathyroid mediated
- secreting PTHrP (malgnancy)
- increased calcitriol (secondary to malignacy)
others
- lithium
- thiazides
- adrenal insufficiency
- parenteral nutrition
hyperthyroid and malignancy are the most common causes
Diagnostics for hypercalcemia
confirm the presence of the hypercalcemia
- get corrected calcium = serum calcium + 0.8 x (4-serum albumin)
- good history
- measure PTH
if PTH high = think primary hyperparathyroidism
if mid = find evidence to r/o hypocalciruic hypercalcemia (rare)
low = look for causes like vit D and PTH-related proteins
Management of hypercalcemia
- mild
- moderate
- severe
Mild = pts. with asymptomatic or have mild symptoms
calcium < 12 mg/dL
- no immediate treatment needed; advise to avoid calcum…..
- lithum
- thiazides
- volume depleteion (make sure theyre hydrated)
- inactivity
- calcium and vit D supplements
- high dietary calcium
Moderate = calcium between 12-14
- if chronic and aysmptomatic: treat like mild
- if acute and symptomatic: treat like severe
Severe = calicum > 14
- if symptomatic…
- give IV ISOTONIC salie
- calcitonin
- bicarbonate
Clincal Signs of Hypocalcemia
Acute Signs
- paresthesias
- muscle twiching
- trousseaus signs
- seizures
- prolonged QT
- hypotension
- heart ailure
- arrythmias
- papilledema
Chronic
- etopic calcification
- extrapryamidal signs
- parkinsonism
- dementia
- dry skin
- subcapsular cataracts
Conditions which may cause hypocalcemia
hypoparathyroidism
- cataracts form
- cognitive impairment
- dystonia
- dementai
- psychosis
- moodiness
pseudohypoparathryoidism
- skeletal abnormalites
- intellectual impairment
- hormone insufficiens
Vit D deficiency
- rickets
- osteomalacica
rare could ahve autosomal dominat hypocalcemia
Managment of hypocalcemia
for severe symptoms (tetany, seizures, prolonged QT)
- IV calcium
- then calcium gluconate (oral)
for mild/asymptomatic hypocalcemia
- oral calcium supplements
- calcuim carbonate or citrate
dont forget to give vitamin D and magnesium!!
clinical signs of hyperkalemia
Severe with K >7.0
- ascending muscle weakness
- paralysis
- cardiac arrythmias & abnormalities….
- RBBB/LBBB
- AV block
- bradycardia
- sinus arrest
- VT
- Vfib
- asystole
- death
Causes and Etiologies of Hyperkalemia
- ingestion of excess K (but this is rare: normally the body will regulate this and push it into the cells via insulin & use aldosterone to increase Na reabsorbtion and K secretion)
- imparied urinate secretion (aldosterons impaired secretion or response, acute/chronic kidney disease, decrease in Na or H20)
other causes
- metabolic acidosis
- insulin deficiency, hypergycemia or hypesomlarity
- beta blocker
- exercise
- hemolyzed specimen sample!! (false +)
diagnosis of hyperkalemia
EKG findings
- history and physical
- EKG!!! to see if any changes
- BMP
- evaluate hypoaldosteronsim
EKG findings
- tall peaked T waves
- shortened QT interval
- legthened ORS == leads to asystole
- absent P waves
Management of Hyperkalemia
emergency and otherwise
Emergency
- IV insulin (add dextrose but not if they’re hyperglycemic)
- hemodialysis
- albuterol
- diuretics
- GI cation exchangers
other
- dietary modification
- diuretics
- bicarbonate
- GI cation exchangers (binders)
Hypokalemia signs and symptoms
seen as a K < 3.5
- severe muscle weakness or rhabomyolysis
- kidney dysfunction
- hypertension
EKG changes
- PACS
- bradycardia
- Atrial or ventricular tachycardia
- AV blocks
- PVCs
Diagnosis of hypokalemia
EKG findings
history and physical
BMP
EKG with
- ST depression
- Decreased amplitude of T waves
- increase amp. of U waves
- prolonged QT
- assess acid base status: bicarb, albumin, chloride, pH urin, VBGABG, electrolytes
- assess urine K: 24 hour or a urine potassium to cr ratio
- urine Na and chloride too
why does hypokalemia occur
- GI losses (like vomiting/diarrhea)
- urinary losses ( diueretics, MRAs, kidney disease, polyuria, some drugs)
- decreases intake of K
- aldosteronsim (increased excretion)
reasons for uptake into cells and therefore less in serum
- increased pH
- insulinemia
- increase beta adrenergic (NE and N)
- hypokalemia paralysis (rare)
- increaed in blood cell production
others
- increase sweating
- dialysis
- plasmapheresis
Management of hypokalemia
mild/moderate K= 3-3.4
- oral potassium (Kchloride or phosphate)
- k sparing diuretics
severe K= < 2.5-3
- correct rapidly with oral or IV potassium
- monitor K for rebound hyperkalemia
- contiuous EKG
What is BUN and Creatitine
BUN: measures the urea nitrogen in the blood
- urea nitrogen is a waste from when the liver breaks down protein
- excreted by the kidneys
Creatinine
- a waste product of creatine catabolsim from muscles
- excreted in the kidneys
Reasons for elevated BUN
- kidney dysfunction
- high protein intake
- GI bleed
- catabolic (breakdown) states like fever, steroid use, bruns
- rhabdomyolysis
- dehydration
- CHF
- shock
- dimished blood volume
- Urinary tract obstruction
- bladder dysfunction
Reasons for elevated creatinine
- high protein intake
- rhabdomyolysis
- GI bleed
- exercise: strenuous
- hypovolemia
- drugs
- renal disease or failure
- surgery
- shock
