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