Renal Assessment- Part 1: Electrolytes Flashcards
Test 3
TBW =
Body wt x 0.6
Which body fluid is more immediately altered by kidneys?
ECF
Osmolar homeostasis is mainly mediated by sensors located in the ___________
Anterior hypothalamus
What do the osmolality sensors stimulate? (3)
Thirst
Pituitary release of vasopressin (ADH)
Cardiac atria release of ANP
Volume homeostasis is mediated by ________
Juxtaglomerular apparatus
What happens if you decrease volume at the Juxtaglomerular apparatus?
triggers RAAS –> increases Na/H2O reabsorption
What is ECF?
Plasma & ISF
Plasma is ____ of ECF and ISF is _____ of ECF
1/4 or 25%
3/4 or 75%
ECF is about ______ of TBW
less than half
What is the normal Na range?
135 - 145 mEq/L
What value of Na do we want to correct before elective Sx?
<125 or >155
What are causes of hyponatremia with: hypovolemia; euvolemia; hypervolemia?
Hypo: diuretics, G.I. loss, burns, trauma
Euvo: salt restrictions, endocrine related (hypothyroid, SIADH)
Hyper: ARF/CKD, HF, Increased endogenous vasopressin (ADH), over fluid-resuscitation
You will see ______ changes with hyponatremia. Describe them.
Neurological
Na 130–135: could be assymptomiatic; HA; N/V
120-130: Malaise; unsteadiness; HA; N/V; confusion; muscle cramps; fatigue
<120: seizures; respiratory arrest; death; brings them herniation;
Are numbers or trends more important?
Trends
How do you treat hyponatremia?
Underlying cause & volume status
- electrolyte drinks, NS, diuretics
-Hypertonic Saline
How do you give Hypertonic 3% NaCl?
80ml/hr over 15 hrs
Correction should not exceed 1.5 mEq/L/hr
What happens if you give Hypertonic 3% NaCl too fast? What is the exception?
if given greater than 6 mEq/L in 24 hrs –> Osmotic Demylination Syndrome –> permanent Neuro damage
Exception: seizures
Give 3-5 ml/kg over 20 min until seizures stop
we check Na every ____ while replacing
4 hr
what causes hypernatremia with: hypovolemia; euvolemia; hypervolemia?
hypo: Renal/GI loss
Euvo: DI; excessive evaporation
Hyper: excessive sodium/bicarb; hyperaldosteronium, cushings
What are symptoms of hypernatremia?
Neuro
Orthostasis
Restlessness
Lethargy
Tremor/muscle twitching
Seizures
Death
What is the treatment for hypernatremia?
Root cause/Volume status
Hypovolemic: NS
Euvo: Water PO or D5W
Hyper: diuretics
With hypernatremia, how fast can you lower the Na? why?
<0.5 mmol/L/hr AND <10 mmol/L/day
Avoid cerebral edema, seizures, and neuro damage
_____ of K+ is in the ECF. Where is the majority of it?
<1.5%
ICF
What does serum K+ reflect?
Transmembrane K+ regulation
What is the normal range for K+?
3.5 - 5.5 mmol/L
________ causes the distal nephron to secrete K+
aldosterone
In renal failure, where does K excretion shift to?
It declines and shifts to the GI system
What are your most common causes of hypokalemia?
Renal: diuretics; hyperaldosteronism
GI: N/V/D; malabsorption
Intracellular shifts: alkalosis, Beta-agonists, insulin
DKA
Thiazide diuretics
Hyperventilation
Excessive licorice
what candy causes hypokalemia?
Excessive licorice
What are symptoms of hypokalemia?
Cardiac: dysrhythmia
U-wave
Neuromuscular: muscle weakness/cramps
-ileus
What is the treatment for hypokalemia?
Underlying cause
K+ PO > IV
10-20mEq/L/hr IV
Each 10 meq of IV K+ raises serum K+ by _______
0.1 mmol/L
What causes hyperkalemia?
-renal failure
-hypoaldosteronism
-drugs that inhibit RAAS
-drugs that inhibit K excretion
-Depolarizing NMB (Succs)
-acidosis
-cell death
-massive blood transfusion
What are symptoms of hyperkalemia?
Chronic: minimal -malaise; GI upset
Acute: skeletal muscle paralysis; decreased fine motor; cardiac dysrhythmias
what EKG changes would you see with hyperkalemia?
Peak T wave
Disappearance of P wave
Prolonged QRS
Sine waves
Asystole
How much does Succ increase serum K by?
0.5 - 1.0 meq/L
What is the initial Tx for hyperkalemia? What are other Tx?
Initial: Ca++ –> stabilizes membrane
Dialyze w/i 24h prior to Sx
Hyperventilate
Insulin and glucose
Bicarb
Loop diuretics
Kayexalate
With hyperventilation increasing pH by 0.1 –> ____ K by _________
decrease
0.4 - 1.5 mmol/L
With hyperkalemia, how much insulin and glucose do we get for treatment? How long does it take to work?
10u of insulin
25g of D50
10 - 20 mins
___% of Ca is in ECF and the rest is stored in ______
1%
bones
_____% of plasma Ca is protein bound to ______. Is it active or inactive?
60%
albumin
inactive
What type of Ca is physiologically active?
Ionized Ca
What is the range of ionized Ca?
1.2 - 1.38 mmol/L
How is ionized Ca levels affected by pH and albumin?
Increased pH/albumin = decreased ionized Ca
What hormones regulate Ca? (3)
Parathyroid hormone: GI/renal absorption; regulates bone/blood levels
Vitamin D: intestinal absorption
Calcitonin: promote storage in bone
What causes hypocalcemia?
-decrease parathyroid hormone (PTH) secretion
-magnesium deficiency (required for PTH production)
-low vitamin D
-renal failure
-massive blood transfusion
Vitamin D is required for _______ production
Parathyroid hormone (PTH)
Hypocalcemia from decreases in PTH can lead to ________. Why is this important? What consideration should we have with this?
Laryngospasm
Life-threatening complication
Be cautious when extubating and always have a plan
What are the main causes of hypercalcemia? What are the values for this? What are the less common causes?
Main causes:
Hyper-parathyroid >11
Cancer > 13
Less common:
Vitamin D intoxication
Milk – alkali syndrome
Granulomatous disease (sarcoidosis)
What are the symptoms of hypercalcemia?
Confusion
Lethargy
Decrease deep tendon reflexes
Hypotonia
N/V
Short QT interval
Chronic: Nephrolithiasis; hypercalciuria
What are the symptoms of hypocalcemia?
Paresthesias
Irritability
Hypotension
Seizures
Myocardial depression
Prolonged QT interval
Laryngospams <—- life threatening**
What are the causes and symptoms of hypomagnesium?
Causes: diet/absorption
Renal wasting
Symptoms: muscle weakness/excitation
Seizures
Ventricular dysrhythmias (VTach/ torsades)
What is the Tx of hypomagnesium?
Depends on severity
Slow mag infusion
Torsades/seizure –> 2g mag sulfate
What are the causes of hypermagnesium?
Over treatment from preeclampsia/eclampsia or Pheochromocytoma
what are the symptoms of hypermagnesium?
4-5: lethargy; N/V; flushing
> 6: hypotension; decrease deep tendon reflexes
> 10: paralysis; apnea; HB; cardiac arrest
What is the Tx for hypermagnesium?
Diuresis
IV Calcium
Dialysis
What considerations should we have if pt on gtt mag?
need to check levels every 4 hrs
