Lecture 1B: Fluids and electrolytes continued: electrolyte disorders
What causes extra-renal fluid loss in hypovolemic hyponatremia? (4)
-(outside of the kidneys fluid loss; MOST COMMON) -loss of body fluids containing sodium (ex: prolonged vomiting, severe diarrhea, or sequestration of fluids in a 3rd space) -MADE WORSE by consumption of hypotonic IV fluids or beverages (water) -ADH secretion worsens dilution
What is the normal calcium range? And normal ionized range?
-8-10 mg/dL and 4-5.6 mg/dL
Hypermagnesemia ECG changes:
-AV block and prolonged QT on ECG
CHIMPANZEES: hypercalcemia causes
-Calcium suplamentation -Hyperparathyroidism -Immobility/iatrogenic -Mets/milk-alkali syndrome -Pagets disease -Addisons disease/acromegally -Neoplasm (colon, lung, breast, prostate, multiple myeloma) -zollinge-elllison (men-I) -Excessive vitamin D -Excessive vitamin A -Sarcoid
What is Hypokalemia and what is it caused by?
-Defined as a potassium level <3.0 meq/L -caused by decreased intake, GI losses, renal losses, skin losses, redistribution (K+ intracellular shift) from insulin overdose or severe metabolic alkalosis third space losses
True or False: Urine concentration in Diabetes Insipidus is concentrated.
-False dilute
True or False: If you have a patient who is hypocalcemic with a normal albumin level it is not necessary to check PTH levels.
-False: you should check them
Hypercalcemia treatment: (5)
-HYDRATE!! Increase hydration, normal saline crystalloid augments excretion of calcium -increase mobility -loop diuretics -Calcitonin and biphosphonates for more sever cases -oral phosphate binds calcium
Why is it important to correct pH before before giving potassium in someone who is acidotic?
-It is important tot correct the pH because the potassium can look falsely elevated
Management of Euvolemic hyponatremia? (4)
-MCCL SIADH -restric fluids. Severely hyponatremia patients should have a reduced free water intake -find cause -can use pharmacologic aids that antagonize ADH
Pseudohyponatremia:
-May occur in cases of hyperlipidemia or hyperproteinemia -lipid or protein occupies space in the volume of serum taken for analysis -concentration of sodium in the serum itself is not affected. Never methods of measuring serum electrolytes with ion selective electrodes circumvent this problem (Basically proteins/lipids add to the volume screwing the sodium results in the volume)
PTH and calcium: (3)
-PTH modulates serum calcium levels -high PTH in response to decreased Ca levels -low PTH in response to increased CA levels
Hyperkalemia treatment: step 3 (5)
-Shift potassium into cells: put it where it can't do harm; buys time to rid it from body -correct underlying acidosis -bicarbonate: 1 amp (50meq) shifts k+ into cells if acidosis is present -give glucose, 50-100 g IV insulin, 10 units (this drives K intracellular) -beta2 agonists: (albuterol ) causes trans cellular shift. use caution in presence of coronary artery disease
Hyperkalemia treatment: Step 1 (2)
-Stabilize the heart: obtain ECG, calcium salts (Cl or CL gluconate 10%) antagonize the effects of potassium oncardiomyocyte membranes (cardiac protectant); does not affect plasma K+ level; -if abnormalities seen on ECG or K+ level >6.5 initiate calcium therapy to prevent lethal cardiac arrhythmias from developing and institute other therapies to decrease potassium levels
Hypokalemia ECG changes
-T-wave flattening, U-waves, PR and QT widening on ECG
True or False: alkalosis may affect ionized (free) levels of Ca2+ in the body.
-True
True or False: each 3meq rise in Na+ reflects a 1 liter loss of free water
-True
True or False: hypercalcemia of malignancy implies terminal stage of disease.
-True :(
What is hyponatremia defined as?
-a serum plasma sodium <135 meq/L
What does acidosis and alkalosis do to serum potassium?
-acidosis increases serum potassium, and alkalosis decreases serum potassium due to ionic shifts
Hypernatremia treatment course: (3)
-based on etiology; evaluate extracellular volume status and whether it is an acute or chronic problem -stop the sodium; give free water using D%W -considering administering desmopressin (DDAVP) in the setting of Diabetes insipidus (ADH deficiency)
Treatment of hypocalcemia: (5)
-calcium (pos ion trope, affects SVR) -calcium chloride when severe (watch for tissue extravasation) gives 6.5 mmole -calcium gluconate 10% gives 2.2 mmole -calcium carbonate (tums) 200-400mg -Rapid IV administration can result in bradycardia, asystole (watch for local tissue injury from extravasation)
Calcium and phosphate relationship:
-calcium goes up, phosphate goes down and vice versa
How to replace fluids in hypernatremia: (4)
-calculate h2O deficit: (140-Na+) X (0.6 X weight in kg)/140 -replace slow to avoid cerebral edema -1/2 of deficit given over first 8 hrs with remaining 1/2 over next 16-24 hrs -CAUTION: rapid correction can lead to cerebral edema and herniation (brain stem through foraman magnum)
Hypomagnesemia: (2)
-commonly seen in surgical patients; important in energy metabolism, protein synthesis, cell division and calcium regulation in muscle -augments the loss of K+ and phosphate
What are the symptoms of hypokalemia?
-dec DTR's, muscle weakness, constipation, paralytic ileus, paresthesias and cardiac arrhythmias, Enhances digitalis toxicity
Causes of hypomagnesemia:
-decreased intake, poor diet, gastrointestinal losses (massive diarrhea), malnutrition, malabsorption syndromes, pancreatitis, drug effects (diuretics, aminoglycosides, amphotericin)
Hypovolemic hyponatremia: (4)
-deficiencies in total body water and total body sodium -sodium loss > water loss -lack of sodium causes less water to be reabsorbed leading to hypovolemia and decreased blood volume -ADH is increased in order to maintain blood volume, furthering the plasma dilution and hyponatremia
Hyperkalemia definition:
-defined as a potassium level >6.0 meq/L
Hypernatremia:
-defined as a serum sodium>145 meq/L
Hypophosphatemia:
-defines as serum phosphate <2.5 mg/dL
Management of hypervolemic hyponatremia? (3)
-dialysis -fluid restriction and inhibition of water reabsorption -treat underlying problem
Signs and symptoms of hypocalcemia:
-diarrhea, paresthesias, circumoral paeresthesias, muscle cramping, increased DTR's, tetany- seizures, s/p thyroid surgery, calcium channel blocker overdose
How would you manage hypovolemic hyponatremia? (5)
-expand intravascular volume using normal saline or 3% saline -need to calculate sodium deficits first (mEq Na needed=140 - current NA) X (0.6 X wt in kg) -replace 1/3 deficit over first 6-8 hours -replace remaining in next 24-48 hrs -correct no faster than 0.5 mEq/L/hr (osmotic demyelination syndrome (ODS); central pontine myelinolysis CPM)
What causes hypertonic hyponatremia? (4)
-heart failure -cirrhosis -nephrotic syndrome -decreased GFR
What is the ultimate method of removing potassium from the body?
-hemodialysis; used if all else fails
What causes low PTH: (2)
-hypoparathyroidism -low magnesium
What are 5 types of hyponatremia?
-hypovolemic -hypervolemic -euvolemic -pseudohyponatremia -trans-locational hyponatremia
Hypophophatemia treatment:
-if mild or no symptoms initiate oral phosphate therapy (one tab of potasssium phosphate per day) -if major symptoms (<1.0 mg/dL) initiate parental treatment And give 2.5-5mg/kg over 6 hours
What is hyperkalemia cause by?
-impaired renal excretion, renal failure, adrenal insufficiency, type IV renal tubular acidosis, increased intake, endogenous release (crush injury, reperfusion, cellular hemolysis), ionic shifts, drugs
Trans-locational hyponatremia:
-in the setting of hyperglycemia a lab artifact can occur: water moves out of cells in the ECF; serum sodium concentration falls about 1.6 mEq/L for every 100-mg/dL rise in the serum glucose above normal value (caused dilution)
What causes hypernatremia?
-inadequate free water replacement, IV administration of hypertonic saline solutions, excess free water loss (DI), steroid use, adrenal disorders, large Na+ containing loads (bicarbonate, abx)
Hypertonic hyponatremia:
-increase in both total body sodium and increased ECF volume -excess sodium drives the reabsorption of water
Hypermagnesemia symptoms: (3)
-increasing neuromuscular and CNS abnormalities -lethargy, weakness, resp. Depresssion, and loss of DTR's -hypotension, bradycardia, DEATH!
What are the symptoms of hypernatremia? (3)
-lethargy, tremulousness, ataxia, dementia, decreased BP, poor skin turbot, dry mucous membranes -thirst and weakness are common -severe neurological symptoms can occur secondary to cellular shrinkage and tearing of cerebral blood vessels
Hypocalcemia: (3)
-low serum calcium levels; patient symptomatic at <8 mg/dL -98% of Ca in the skeleton, 2% circulating, of that 2% 50% is bound to albumin and 50% is free -hypoalbuminemic patients will have normal ionized (free Ca) fraction
Magnesium and cardiac uses:
-mag replacement used in torsades treatment, arrhythmis prevention during AMI, pre-eclampsia and pre-term labor
When you see hypercalcemia you should think ______________.
-malignancy
What causes renal fluid loss in hypovolemic hyponatremia? (2)
-mineralocorticoid deficiencies or salt-losing nephropathy -Diuretics: THIAZIDE DIURRETICS cause increased sodium excretion-> water follows and then in turn vasopressin (ADH) is released in response to volume depletion
Signs and symptoms of hyperphosphatemia: (2)
-most symptoms related secondarily to hypocalcemia and ectopic calcification -ectopic calcification is defines as inappropriate biomineralization occurring in soft tissues
What are symptoms of hyperkalemia? (2)
-muscle weakness, paralysis, paresthesia, ventricular dysthymia syndrome, cardiac irritability
Signs/symptoms of hypophospatemia: (5)
-neuromuscular: weakness, malaise, mental status changes, paresthesias -Cardiac: heart failure -Hematologic: hemolysis, decreased 2-3DPG, impaired leukocyte function -gastrointestinal: nausea, vomiting -Skeletal: fractures
Euvolemic Hyponatremia:
-normal sodium stores but excess water -caused by SIADH (syndrome of inappropriate ADH secretion) leads to excessive ADH release so volume water retained leading to dilutions
Hypercalcemia: (3)
-often asymptomatic -critical when calcium level >12 mg/dL -calcium levels >13 mg/dL can result in nephrocalcinosis and acute renal failure
Hypomagnesemia treatment: (4)
-oral replacement with milk of magnesia -IV replacement MgSO4, 1 gram contains 8.112 meq Mg -Do NOT exceed 100 meq/day -can follow with reflexes on PE, serum levels and ECG
What can happen if you correct hypovolemic hyponatremia faster than 0.5 mEq/L/hr?
-osmotic demyelination syndrome (ODS) aka central pontine myelinolysis (causes seizures) -greatest risk if hyponatremia>48 hours
What causes high PTH: (5)
-pancreatitis -hyperphospatemia - massive blood transfusion (EDTA) -renal insufficiency -Drugs
Hyperkalemia ECG changes:
-peaked T-waves, QT prolongation on ECG, QRS widening
ECG changes seen in hypocalcemia?
-prolonged QT interval in ECG
Hypermagnesemia:
-rare!; magnesium level>2.5 meq/L -can occur with overzealous treatment of eclampsia
IV K+ replacement: (3)
-rates of 0.25 to 0.50 mEq/kg/hr are safe, usually 20meq KCL per 100cc D5W or NS over 1 hour -IVF concentration of <40 mEq/L are safe -Infusion can be painful via peripheral IV lines
Hyperkalemia treatment: step 2 (3)
-remove potassium from the body -Kayexalate (sodium polystyrene): cation esxcange resins. Can give 20-30 mg PO in 50 ml 70% sorbitol or 50-100 g in 200 ml water as an enema -Loop diuretics first choice if possible (can't diurese someone who is anuric)
Causes of hypermagnesemia:
-renal failure, rhabdomyolysis (crush injuries/burns), severe metabolic acidosis, antacid overuse, adrenal insufficiency, hypothyroidism
Hypokalemia treatment:
-replace orally or intravenously with K+ salts (KCL); life threatening situations require IV administration -oral sources include bananas, salt substitute
Hyperphosphatemia treatment: (4)
-restrict intake -increase renal losses (saline loading, acetazolamide) -increase gut losses (give aluminum hydroxide, 20-45 ml q 6 hours) -consider dialysis with renal dysfunction if other methods not adequate
What are 3 things that sever hyponatremia can lead to?
-seizures -coma -permanent neurological damage (Usually caused by excess body water in relation to sodium, rather than not enough sodium ex: failure to really clear excess water)
What is the initial work-up for hyponatremia?
-serum osmolality (particles)
What is trousseau's sign?
-sign of hypocalcemia; carpopedal spasm; when you pump up a BP cuff above systolic pressure for 3 minutes hand/arm spasms
What is chvosteks sign?
-sign of hypocalcemia; when you tap on facial nerve the face twitches
Hypercalcemia symptoms: (2)
-stones, bones grones, abdominal moans, and psychic overtones (also for parathyroidism) -Confusion, nausea and vomiting, mental status changes, nephrolithiasis, lethargy, puritis
Hypermagnesemia treatment: (5)
-stop the magnesium! -Supportive care ABCs -if mild, hydrate -cardio toxicity management with IV calcium -if sever dialysis
What are the side affects of rapid magnesium infusion?
-sweating, bradycardia and hypotensiion
Causes of hypercalcemia: (4)
-thiazide diuretics -pagets disease -hyperparathyroidism -prolonged immobilization/bedrest
Hypophospatemia causes: (3)
-transcellular shift causes: increased intake, anabolism, carb load, acidosis, alcholism -renal causes: acidosis, impaired reabsorption, hyperparathyroidism, hypomagnesemia, hypokalemia -gastrointestinal causes: malabsorption, diarrhea, nasogastric suction, phosphate binding antacids
Hyperphosphatemia causes: (3)
-transcellular shift causes: sepsis, catabolism, cancer, hepatitis -Renal causes: renal insufficiency, pseudo and hypoparathyroidism -gastrointestinal causes: increased intake, often from antacids, increased vitamin D
What are some signs of CNS dysfunction in hyponatremia?
-weakness, hyperactive DTRs, twitching, lethargy, nausea, vomiting and muscle cramps, altered mental status, irritability -severe hyponatremia may result in seizures, coma or resp arrest
Signs and symptoms of hypomagnesemia:
-weakness, mental status changes, hyperreflexia, vertices nystagmus, seizures and arrhythmias (ventricular also), dysphasia, tetany
Hyperkalemia tratment steps:
1. Stabilize the heart 2. Remove potassium from the body 3. Shift potassium into the cells
What is the sodium deficit calculation and what is it used for?
mEq Na needed=140 - current NA) X (0.6 X wt in kg); used to calculate sodium deficits needing replacement in hypovolemic hyponatremia