Hyper-Hypokalemia & Hyper-Hyponatremia (Andelin) Flashcards
What is considered hyponatremia?
Low serum sodium <135 mEq/L
Mild hyponatremia 130-134 mEq/L
Moderate hyponatremia 120-129 mEq/L
Severe hyponatremia <120 mEq/L
What is considered severe hyponatremia?
Severe hyponatremia <120 mEq/L
Symptoms of hyponatremia?
Na+ < 125 mEq/L (>125 mEq/L = asymptomatic)
Mostly neurological symptoms: Headache, fatigue/lethargy, Dizziness, nausea, Gait instability, Confusion, Psychosis, Seizures, Coma
Hypovolemic hyponatremic exam findings
Hypotension
Tachycardia
Poor capillary refill
Increased skin turgor
Dry oral mucosa or tongue fissuring
Flat JVD
Hx of decreased urine output
Hypervolemic hyponatremic exam findings
Hypertension
Sacral or LE edema
JVD
Dilated IVC on ECHO
Cause of Hypovolemic Hyponatremic with Urine Na+ >30 mEq/L
Renal fluid loss: Diuretic excess
Causes of Hypovolemic Hyponatremic with Urine Na+ <30 mEq/L
Extrarenal fluid loss:
Vomiting
Diarrhea
Third spacing (burns - lots of water loss)
Causes of Euvolemic Hyponatremic with Urine Na+ >30 mEq/L
Drugs
SIADH
Causes of Euvolemic Hyponatremic with Urine Na+ <30 mEq/L
(Very dilute urine)
Primary polydipsia
Causes of Hypovolemic Hypernatremic with Urine Na+ <30 mEq/L
Nephrotic Syndrome
Heart failure
Cirrhosis
Causes of Hypovolemic Hypernatremic with Urine Na+ >30 mEq/L
AKI
CKD
Treatment of hyponatremia
Give hypertonic saline (3%)
Acute (<48 hrs) rapid correction
Chronic (>48hrs) avoid rapid correction (ODS); increase 8-10 mEq/L per day; no more than 18 in first 48 hrs
Osmotic Demyelination Syndrome (ODS)
In the case of a patient with hyponatremia where there is rapid Na+ correction. Demyelination occurs in the pontine (pons) and extrapontine neurons typically 2-6 days later. Symptoms are often irreversible (very serious) can potentially develop locked-in syndrome (awake but unable to move or communicate)
Diagnosed with head MRI about 3-4 weeks later.
SIADH
too much ADH
inability to suppress ADH secretion, lots of water retention (aquaporins); urinary Na excretion. Urine will be concentrated (urine osmolality>serum osmolality)
Euvolemic hyponatremia
Urine Na+ > 30 mEq/L
Common causes of SIADH
head trauma or CNS disorder
Paraneoplastic syndrome - small cell carcinoma of the lung (most common)
Pneumonia
Carbamazepine
Hyponatremia Summary
Common in older adults and hospitalized patients.
Na > 125 mEq/L = asymptomatic
Na < 125 mEq/L = neurological symptoms
Hypovolemic, Euvolemic and Hypervolemic
Workup includes: serum osmolality, urine osmolality and urine sodium
Treatment for acute = rapid correction, chronic = avoid rapid correction b/c ODS risk.
Cirrhosis causes what kind of electrolyte abnormality?
Hypervolemic hyponatremia
Serum Na+ <135 mEq/L
Urine Na+ <30
Treat with IV isotonic saline (asymptomatic)
Hypertonic saline (symptomatic)
Excessive diuretics causes what kind of electrolyte abnormality?
Hypovolemic hyponatremia
Urine Na+ > 30 mEq/L
Excessive diarrhea/vomiting causes what electrolyte abnormality?
Hypovolemic hyponatremia
Urine Na+ <30 mEq/L
What is considered hypernatremia?
Elevated serum sodium ( >148 mEq/L)
Primarily seen in infants and elderly
Symptoms of hypernatremia?
Primarily neurological symptoms:
Irritability
Altered mental statusLethargy
Ataxia
Hyperrelexia
Intracranial hemorrhages
Pathogenesis of hypernatremia
Defect in urine concentrating capacity (ADH prob-suppressed or not responsive) coupled with inadequate water intake.
- unreplaced water loss
- sodium overload
What is the risk of rapid correction in hyponatremia treatment?
Osmotic Demyelination Syndrome (ODS)
What is the risk of rapid correction in hypernatemia treatment?
Cerebral edema
Treatment of hypernatremia
Give hypotonic saline or 5% Dextrose in water (D5W)
Acute (<48 hrs) rapid correction
Chronic (>48hrs) avoid rapid correction (cerebral edema); lower 10-12 mEq/L per day; no more than this
Hypernatremia Summary
Common in infants and elderly.
There are mainly neurological symptoms.
Na > 148 mEq/L
Workup includes: BMP or CMP
Treatment for acute = rapid correction, chronic = avoid rapid correction b/c cerebral edema risk.
What is considered hyperkalemia?
Elevated serum potassium (> 5.0 or 5.5 mEq/L)
Symptoms of hyperkalemia?
Depends on severity of hyperkalemia (can be asymptomatic, mild, or life threatening)
Can cause cardiac arrhythmias (V fib), skeletal muscle weakness, or metabolic acidosis
ECG changes in hyperkalemia
6-7 mEq/L = peaked t waves
> 9 mEq/L = extremely severe hyperkalemia - V fib
What are some common causes of hyperkalemia due to transcellular shift?
metabolic acidosis
insulin deficiency, hyperglycemia, hyperosmolality
increased tissue catabolism (rhabdomyolysis)
Meds: B2 blockers or succinylcholine
Blood transfusions
Exercise
What are some common causes of hyperkalemia due to decreased renal excretion?
Low aldosterone secretion (ACEis/ARBs)
Aldosterone resistance (spironlactone/trimethoprim)
AKI/CKD
Hypovolemia
Ureterojejunostomy (kidneys attached to bowel)
Intrinsic renal defect (rare)
What is the workup for hyperkalemia?
BMP or CMP (ALWAYS repeat to rule out lab error)
ECG - look for cardiac abnormalities
Hyperkalemia Treatment
Ca BIG K
Ca - IV Calcium gluconate (indicated when peaked t waves are present)
B - Inhaled B2 agonist (albuterol) or IV Bicarbonate (less effective)
IG - IV insulin and glucose
K - Oral Kayexalate (gets rid of K+)
Treatment of IV Calcium gluconate
used in hyperkalemia when peaked t waves are present; stabilizes cardiac membrane
Treatment of inhaled B2 agonist
albuterol - used in hyperkalemia when caused by changes in transcellular shift
Treatment of IV Bicarbonate
used in hyperkalemia when caused by changes in transcellular shift (less effective then B2 agonist - albuterol)
Treatment of IV insulin and glucose
used in hyperkalemia when caused by changes in transcellular shift
Treatment of oral Kayexalate
used in hyperkalemia to get rid of K+; exchanges Na+ ions for K+ primarily in the colon (cation exchange)
Hyperkalemia Summary
Common (kidney injury)
K+ > 5.0 or 5.5 mEq/L
Cardiac arrhythmias/ Muscle weakness
Workup includes: BMP or CMP (REPEAT) and ECG
Treatment: Ca BIG K
What is considered hypokalemia
low serum potassium (< 3.5 mEq/L)
Symptoms of hypokalemia
usually not symptomatic until < 3.0 mEq/L
Skeletal muscle weakness (severe cases - diaphragmatic weakness - breathing)
Muscle cramps - potentially rhabdomyolysis
Cardiac arrhythmias
Metabolic alkalosis
ECG changed in hypokalemia
3.5 = low t wave
3.0 = low t wave; high u wave
What are the three main reasons for hypokalemia?
- Transcellular shift (increased K+ uptake by cells; out of blood)
- Extra-renal loss
- Renal loss
What are the 3 main causes of transcellular shift in hypokalemia?
- B agonist (abuterol)
- Metabolic alkalosis (increase in arterial pH)
- Insulin (DKA treament - IV insulin leads to intracellular shift of K+ and thus a decrease in serum K+) and refeeding syndrome
What are the main causes of extra-renal loss in hypokalemia?
GI loss - Vomiting, NG suctioning, diarrhea
Cutaneous loss - sweating
What are the main causes of renal loss in hypokalemia?
Diuretics (thiazides and loop diuretics)
Increased mineralcorticoid activity (hyperaldosteronism)
Hypomagnesium
RTA Type 1 or 2
Intrinsic renal defect (Bartter, Gitleman, Liddle Syndrome)
What is the workup for hypokalemia?
BMP or CMP
ECG - look for cardiac abnormalities
Serum magnesium (remember can lead to persistent hypokalemia)
Hypokalemia treatment
Replace K+ deficit (potassium chloride)
K level will increase by 0.1 mEq/L for every 10 mEq of KCl given
Replace magnesium if low
Repeat K+ to ensure it has normalized
Hypokalemia Summary
Common (due to GI fluid loss, diuretics, insulin)
K+ < 3.5 mEq/L
Skeletal muscle weakness, cramps, and cardiac arrhythmias
ECG: prominent u waves, flat t waves
BMP/CMP, ECG, magnesium check (refractory hypokalemia) and treat by replacing K+ (KCl) and magnesium if low.
