Electrolyte Disturbances Flashcards
Potassium
- where in cell
- importance
- how excreted
- mostly intracellular
- ratio intra/extracellular essential for cell membrane potential
- mostly excreted by kidneys
Hyperkalemia
- value
- Greater than 5.1/5.5 mEq/L
- > 7 can lead to hemodynamic and neuro consequences
- > 8.5 can lead to respiratory paralysis or cardiac arrest, can be fatal
Hyperkalemia
- causes
- Lab/human error (if break RBC can leak K+ out)
- Renal failure and acidosis (Cell will bring excess H+ into cell, push K+ out. Total body K+ has not changed but shift has occurred)
- Cell death (burn, tumor lysis syndrome)
- Drugs, toxins, medications
• K+ supplements
• Non-selective BB (propranolol)
• Succinylcholine (paralytic used in Em medicine)
• Digoxin
• K-sparing diuretics (spironolactone)
• ACEi
• Pentamidine and trimethoprim - ACEi and trimethoprim were most common drug causes in recent study
- Reduced kidney function was common cause in recent study
Hyperkalemia
- EKG findings
- Peaked T wave
- Widened QRS
- Loss of P wave
- Sine wave
- V-fib/asystole
Hyperkalemia
- Treatment
- Treat once confirmed not a lab error, true hyperkalemia and >6.5 or EKG changes
- Figure out the CAUSE don’t just treat the imbalance
Then
1. Membrane antagonism
2. Intracellular shift of K+
3. Eliminate K+ from body
Hyperkalemia
- Membrane antagonism (tx)
• Calcium, stabilizes heart
• Dr. Hunt uses when Hyperkalemic and EKG changes
• Options
- Calcium chloride (3X ca content as ca gluconate, give through central line)
- Calcium gluconate (better if only have peripheral line but less bang for buck)
Hyperkalemia
- intracellular shift of K (tx)
- IV insulin (co-transporter forces K back into cells)
- Albuterol/Salbutamol
- IV sodium bicarb (only if in acidosis)
Hyperkalemia
- Eliminate K from the body (tx)
- Kayexalate (binds in bowel, comes out in stool). Risk of colonic necrosis
- Furosemide (risk of hypokalemia). Dr. Hunts first option, let nephrologist order kayexalate
- Dialysis: if reduced kidney function, not a rapid solution
Hyperkalemia
- mnemonic
C BIG K Di • Calcium • Bicarb, beta agonist • Insulin • Glucose • Kayexelate, Lasix • Dialysis
Pseudohyperkalemia
- D/t collection and storage of specimen
- Pt clenched fist when sample was taken, difficulty collecting sample
- Cooling of sample or deterioration dt length of storage
- Thrombocytosis
- Severe leukocytosis can cause psuedohypokalemia
Hypokalemia
- value
Serum K+ <3.5 mEq/L, severe is <2.5
Hypokalemia
- first steps
- Assess muscle weakness, increased respiratory muscle use
- EKG changes? Medical emergency
- ABG usually helpful
Hypokalemia
- causes
**Think diuretics and diarrhea
- Drugs (thiazides, furosemide), Toluene in huffers
- GI loss (v/d)
- Hormones (high aldosterone or cortisol)
- Bicarb: metabolic alkalosis (H+ out of cell, K+ in)
- Renal tubular defects
- Mg deficiency
- Decreased intake
- Increased loss
• Renal (CHF, nephrotic syndrome, dehydration)
• Renal tubular defects
• GI losses (v/d/laxatives)
• Drugs (diuretics, ampho B, mannitol, aminoglycosides)
- Transcellular shifts
• Alkalosis (vomiting, diuretics)
• Insulin
• Beta agonists
Hypokalemia
- clinical presentation
- CV: arrhythmia, EKG change
- Skeletal muscle: weakness (MC presentation in ER), cramps, tetany, paralysis (K<2)
- Smooth muscle: constipation, urinary retention
- Metabolic alkalosis
Hypokalemia
- EKG changes
- PR prolongation
- T wave flatten/inversion
- ST depression
- U waves
- Long QT interval (T&U fuse together)
Hypokalemia
- Tx
- PO replacement preferred
- IV also an option
- Goals: K between 4 and 4.5 mEq/L
- Might have to increase Mg too (>1.0)
- 1 mEq drop in serum level = 100-200 mEq loss in total body store
- Options
KCL PO, KCL IV, K-phos, K-bicarb, K-citrate
Hypokalemia
- when is IV indicated
- Dysrhythmias
- Prominent sx
- Unable to tolerate PO
- Likely if K<2.5
- Give slowly, preferably via central line
Sodium
- where in body
- how does it move around
- two major hormones related to Na levels
- Extracellular cation, closely related to total body water
- Moves into cells depending on osmolality
- Moved out of cell by Na/K ATPase
- Renin: released with low intravascular volume: triggers Na reabsorption and K secretion in distal nephron via aldosterone
- ADH: released when there is high serum osmolality. Enhances renal water reabsorption. Also triggered by angiotensin, catecholamines, opiates, caffeine, stress, hypoglycemia, hypoxia
Hyponatremia
- serum level
<135 mmol/L
- Must ensure true hyponatremia by adjusting for glucose
- For every 100 above 100 glucose, add 1.6 mmol sodium
Hyponatremia
- first steps
Quickly eval:
- neuro symptoms
- what is the pt’s volume status
Hyponatremia
- Three types
- hypervolemic
- Euvolemic
- Hypovolemic
Hyponatremia
- hypervolemic
- Decreased effective circulating volume, fluid elsewhere (edema): CHF, hepatic cirrhosis, nephrotic syndrome
- ADH is stimulated = water retention
- CHF, cirrhosis, nephrotic syndrome
- Pt will look “wet”
Hyponatremia
- euvolemic
• Inappropriate ADH (SIADH, etc.)
- SIADH, psychogenic polydipsia, beer potomania, adrenal insufficiency, MDMA, hypothyroid
- SIADH causes: tumor, infection, trauma, pulm dz, drugs (diuretics and chemo)
• Pt not wet or dry
Hyponatremia
- hypovolemic
- ADH secretion stimulated by volume depletion: Renal loss, GI loss, excessive sweating, 3rd spacing
- Pt will look dry
Hyponatremia
- clinical presentation
- when <125 mmol/L
• Lethargy, confusion, agitation • n/v • weakness • focal neuro deficits • Seizures (increased risk when <120) • Altered LOC *pts with chronic hyponatremia may tolerate lower levsl without sx than acute onset
Hyponatremia
- workup
• CBC • Electrolytes • Serum osmolality • Uric acid • TSH/cortisol? Urine: UA, urine electrolytes, osmolality, creatinine
Hyponatremia
- Tx overview
- treat the neuro changes and then quickly do nothing
Hyponatremia
- Treatment rule
Rule of 6s:
- Increase Na by 6 mEq per day
- Increase Na by 6 mEq in 6 hours if neuro sx
Hyponatremia
- tx if neuro sx
- IV 100 cc hot salt (3% saline) over 20 min
- Repeat if no improvement.
- Then stop, fluid restrict, admit to hospital
- If neuro persists, consider CT head
Hyponatremia
- Risk of overcorrect
If overcorrect, risk osmotic demyelination syndrome (>10 mEq/L in 24 hour period)
• RF: chronic hyponatremia, serum na <105, alcoholism, malnutrition/liver dz
• Correct with DDAVP and nephrology consult
Hyponatremia
- Tx if no neuro
- Volume resuscitation, saline lock IV, NPO, foley to monitor output
- Replace K will raise serum Na
Hypernatremia
- serum level
> 145 mEq/L
State of hyperosmolality
Hypernatremia
- general causes
- thirst/water access related
- renal concentrating problem (kidney or hormone)
- free water loss
Hypernatremia
- MC etiology
debilitated pts who depend on others for hydration, often long care facilities
Hypernatremia
- Other etiologies
- Reduced water intake
• Inability to obtain water or disorders of thirst perception - Increased water loss
• GI: v/d third spacing
• Renal: diabetes insipidus, renal tubular defects. Diabetes insipidus: loss of large amts of dilute urine, lack concentrating ability in distal nephron. Central: lack ADH secretion, nephrogenic: kidneys don’t respond to ADH
• Dermal: sweating, severe burns - Increased sodium
• Exogenous sodium: salt tablets, hypertonic saline
• Increased reabsorption: Cushings, exogenous corticosteroids, congenital adrenal hyperplasia
Hypernatremia
- work up
- CBC
- serum electrolytes
- serum glucose
- BUN/Cr
- urine electrolytes
- urine osmolalility
- plasma osmolality
- urine output quantity
Hypernatremia
- clinical presentation
- Dehydration
- Anorexia, nausea, vomiting, fatigue
- Lethargy, confusion, coma
- Hyperreflexia, spasticity, tremor, ataxia
- Upgoing toes, hemiparesis
Hypernatremia
- serum osmolality levels and associated sx
- > 350: excessive thirst
- > 375 weakness and lethargy
- > 400 ataxia, tremor
- > 420 focal neuro deficits, hyperreflexia
- > 430 coma and seizure
Hypernatremia
- Dx
- Volume status
- Hypovolemia:
• Urine <10 mEq/L: extrarenal fluid loss
• Urine >20 mEq/L: renal losses - Euvolemia:
• High urine osmolality: increased insensible losses
• Low urine osmolality: diabetes insipidus
Hypernatremia
- Treatment depends on what
timing of onset
- acute (fast onset, <48 hours) = fast treatment
- chronic (slow onset, >48 hours) = slower treatment
Hypernatremia
- Treatment rates for acute and chronic
- Acute: correct at 1 mmol/L per hr
- Chronic: correct at 0.5 mmol/L per hour, no more than 10 mmol/L per 24 hrs
Hypernatremia
- Treatment
- Correct Na
- Replace 50% of free water deficit in first 12-24 hours, remaining over next 24 hours.
- Serial serum and urine electrolytes
- Serial neuro exams
Hypernatremia
- complications
- Coma and seizure
- Cerebral edema if rapid correction
- Intracerebral hemorrhage, esp in neonates
Hypocalcemia
- value
< 8.5 mg/dL
Hypocalcemia
- causes
- Hypoparathyroidism (iatrogenic)
- Vitamin D deficiency
- Hyperphosphatemia (binds calcium)
- Precipitation of calcium
- Chelation of calcium
Hypocalcemia
- what lab needs to be drawn for accurate measure
ionized calcium
Hypocalcemia
- what two states can falsely depress ca measurements
- alkalosis
- hypoproteinemic states
Hypocalcemia
- how to correct calcium lab value
0.8 mg/dL calcium decrease for every 1 g/dL reduction in albumin
Hypocalcemia
- Presentation
- Tetany **
- Paresthesia in circumoral region and extremities
- Laryngospasm, bronchospasm (severe)
- Abd cramps, urinary frequency
- Hypotension and arrhythmia
- Chvostek’s sign (tap facial nerve = twitch)
- Trousseau’s sign (blow up bp cuff = hand spasm)
- EKG: prolonged QT interval
Hypocalcemia
- Treatment
- Symptomatic: 10 ml of 10% IV calcium gluconate over 10 minutes
• Do not give with bicarbonate or phosphate containing solution - Take serial ca measurements
- Correct alkalosis if present
- Long term ca supplement
Hypercalcemia
- value
> 10.5 mg/dL
Hypercalcemia
- causes
- Hyperparathyroidism *
- Malignancy*
- Also: Pagets dz, excessive vitamin D intake, granulomatous disorders, milk alkali syndrome, drugs (thiazides, lithium)
Hypercalcemia
- clinical features
- Anorexia, n/v
- Irritability, confusion
- Weakness, ataxia, lethargy
- Polyuria
- EKG: Peaked T waves, Shortened QT interval
Hypercalcemia
- Tx
- Hydration with normal saline
- Loop diuretics (furosemide)
- Hemodialysis
- Want urine output >3 L day
- Supplement with K and Mg
- Severe: bisphosphonates
Hypomagnesemia
- lab value
mg <1.7 mEq/L
Hypomagnesemia
- how to order
Have to order separate, not on standard CMP
Hypomagnesemia
- causes
- Inadequate intake
- Reduced GI absorption
- Renal losses: diuresis, hyperparathyroidism
- Drugs: theophylline, diuretics, ethyl alcohol, aminoglycoside, amph. B
- Can occur in DKA with decreased K
Hypomagnesemia
- clinical features
- Asx
- Associated with hypocalcemia and hypokalemia
- Anorexia, weakness, paresthesia
- Confusion, seizure, coma
- A fib, potentiates digitalis toxicity
- EKG: Prolonged PR and QT intervals
Hypomagnesemia
- Treatment
- Asx: 2 g oral mg sulfate
- Sx: mg sulfat 1-2 g IV 10 minutes
- Monitor: tendon reflexes, resp rate, urine output
Hypermagnesemia
- lab value
mg >2.5 mEq/L
Hypermagnesemia
- causes
- Antacids or laxatives
- Iatrogenic: mg citrate, antacids
- Hypothyroidism
- Adrenal insufficiency
Lithium
Hypermagnesemia
- Clinical features
- Hyporeflexia, drowsy, skeletal muscle weakness
- Hypotension
- Prolonged PR interval and widening of QRS complex
- Respiratory arrest
Hypermagnesemia
- Treatment
- 10 ml of 10% calcium gluconate IV over time 10 (stabilize cardiac membrane)
- Loop diuretic with ½ normal saline in 5% dextrose: excrete it
- Peritoneal/hemodialysis
