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Therapeutics #2 - Fluid & Electrolytes
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125
Pharmacology
10/12/2009

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Term
Tonicity
Definition
impermeable solute concentration; ability to draw water across a membrane
Term
Osmolality
Definition
total solute concentration (impermeable + permeable); body fcns best between 280-300 mOsm/L
Term
Dextrose 5% in Water (D5W)
Definition
crystalloid taht provides 170 kcal/L; "free" water, use to replace conditions associated with water deficit (i.e. hypernatremia); moves from vascular into other spaces; may cause edema; monitor for hyperglycemia
Term
Normal Saline (NS)
Definition
isotonic; more stays intravascular than D5W; expands volume (used for hypotension or blood loss); replacement fluid for GI tract fluid losses
Term
3% NaCl
Definition
hypertonic fluid; decreases volume of ICF & increases volume of ECF; don't give 3% NaCl if patient is dehydrated
Term
1/2 NS
Definition
hypotonic solution; adds volumne to ICF as well as ECF
Term
Lactated Ringers
Definition
isotonic fluid; expands ECF; similar to NS; used to treat hypotension or blood loss; also has K, Ca, PO4, & lactate; replacement solution when used for fluid resuscitation (acidosis, fluid loss from pancrease, small bowel, saliva, or diarrhea); commonly used for pregnant women
Term
Daily Maintenance Fluid Volume Approximation
Definition
0-10 kg: 100 mL/kg; >10-20 kg: add 50 mL/kg for each kg>10; >20 kg: add 20 mL/kg for each kg>20
Term
Albumin
Definition
colloid that remains in IVF better than crystalloids; least likely colloid to distribute out of IVF
Term
Hetastarch
Definition
colloid that increases risk of bleeding after cardiac & neurosurgery; increases risk of acute kidney injury in sepsis; contraindicated in kidney dysfunction
Term
Dextrans
Definition
colloid that can increase risk of bleeding
Term
Hyponatremia
Definition
when Na < 135 mEq/L; most common electrolyte abnormality; causes: 1) excess ECF water due to impaired excretion of water; 2) non-osmotic release of ADH (occurs in hypovolemia, HF, cirrhosis, nephrosis, & SIADH)
Term
Increased Osmolality
Definition
causes ADH to be released by posterior pituitary allowing free water reabsorption; thirst is also stimulated: drinking water --> decreases it
Term
Hypovolemic Hypotonic Hyponatremia
Definition
pt exhibits both hypernatremia & hyperosmolarity; ADH released; kidney retains sodium; greater loss of Na compared to volume; commonly caused by thiazide diuretics within 2 wks of use
Term
Euvolemic Hypotonic Hyponatremia
Definition
ECF expansion may not be sufficient to cause this; caused by SIADH; also hypothyroidism & renal failure; also, low Na intake/polydipsia
Term
SIADH (Syndrome of Inappropriate ADH Hypersecretion)
Definition
inappropriately increased levels of ADH OR...exaggerated response to normal ADH levels; caused by: tumors, CNS disorders, pulmonary disease, & drugs (carbamazepine, SSRIs, many others)
Term
Hypervolemic Hypotonic Hyponatremia
Definition
condition caused by increased ECF but decreased effective circulating volume; kidneys reacting to perceived hypovolemia: retain more water than Na due to ADH
Term
Causes of Hypotonic Hypovolemic Hyponatremia
Definition
UNa<20 mEq/L; extrarenal losses: diarrhea, skin, lung; UNa>20 mEq/L: renal losses, diuretics
Term
Causes of euvolemic hypotonic hyponatremia
Definition
UNa>20 mEq/L caused by renal failure, SIADH
Term
Causes of Hypervolemic Hypotonic Hyponatremia
Definition
UNa<20 mEq/L: CHF, cirrhosis, neprhosis
Term
Mild Hyponatremia
Definition
Na: 125-135 mEq/L
Term
Moderate Hyponatremia
Definition
Na: 115-125 mEq/L
Term
Severe Hyponatremia
Definition
Na: <115 mEq/L
Term
Clinical Presentration of Hyponatremia
Definition
Mental status: Mild = asymptomatic; Moderate/Severe = cerebral edema --> nausea, headache, lethargy, seizures, coma, permanent brain damage; Hypervolemia = dry mucous membranes, decreased skin turgor, orthostatic hypotension; if HYPERvolemic: edema, weight gain
Term
Osmotic Demyelination Syndrome
Definition
acute decrease in brain cell volume that results in para- or quadraparesis; caused by overly rapid correction of hyponatremia (>12 mEq/L increase of Na per day)
Term
Principles of Treatment for Hyponatremia
Definition
balance risk for neurologic sequelae with osmotic demyelination syndrome; 0.9% NaCl is fluid of choice; pts with severe symptoms, 3% of NaCl temporarily used +/- furosemide; for euvolemic or hypervolemic, use fluid restriction as first strategy
Term
Treatment of Acute/Severely symptomatic Hypovolemic Hypotonic Hyponatremia
Definition
use 0.9% NaCl; initial target of 5% increase or 120 mEq/L is advocated
Term
Treatment of Acute/Severely symptomatic SIADH hypotonic hyponatremia
Definition
use 3% NaCl; when UOsm > 300 mOsm/kg, administer furosemide to prevent volume overload
Term
Treatment of Acute/Severely Symptomatic Hypervolemic Hypotonic Hyponatremia
Definition
use 3% NaCl with fluid restriction and furosemide
Term
Nonemergent Treatment of Hypovolemic Hypotonic Hyponatremia
Definition
replace with 0.9% NaCl while addressing underlying disease states; with mildly asymptomatic patients, initial rates of fluid administration of 0.9% NaCl are often 200-400 mL/hr eventually reducing to 100-150 mL/hr
Term
Estimating ECF Volume Deficit
Definition
ECF desired = normal ECF - ECF current
Term
Nonemergent Treatment of Euvolemic Hypotonic Hyponatremia caused by SIADH
Definition
remove offending drug; treat underlying condition; restrict fluids to 1-1.2 L/day; target Na = 125 mEq/L; increase intake of Na and/or add loop diuretics; give demeclocycline (Declomycin), conivaptan (Vaprisol), or tolvaptan (Samsca)
Term
Demeclocycline (Declomycin)
Definition
used to treat SIADH euvolemic hypotonic hyponatremia; ADRs: nephrotoxicity; Efficacy: takes several days to increase Na, reserved for after trial of fluid restriction/NaCl administration
Term
conivaptan (Vaprisol)
Definition
used to treat SIADH euvolemic hypotonic hyponatremia; MoA: AVP V1A & V2 receptor antagonist which increases free water excretion (IV only!); ADRs: infusion site reactions, arrhythmias in HF pts; Efficacy: not for use in hypovolemic patients, COSTLY!
Term
tolvaptan (Samsca)
Definition
used to treat SIADH euvolemic hypotonic hypernatremia; MoA: AVP V2 receptor antagonist increasing free water excretion; PO; ADRs: no increased arrhythmias in HF pts; Efficacy: not for use in hypovolemic patients; pts allowed to drink fluids
Term
Nonemergent treatment for hypervolemic hypotonic hyponatremia
Definition
fluid restriction (1-1.2 L/d); Na restriction (1-2 gm/d); ACEIs may play a role in hyponatremia related to HF & nephritic syndrome
Term
Monitoring Parameters for Acute/Severe Hyponatremia
Definition
monitor in ICU; mental status exams, cardiac & pulmonary status exams over first 12 hours; monitor serum Na every 2-4 hrs; UOsm, Na, & K every 4-6 hours first day
Term
Epidemiology of Hypernatremia
Definition
pts at highest risk = pts w/ altered mental status, intubated pts, elderly; more common in ICUs than general medicine; acute increase in Na to >160 mEq/L associated with 75% mortality
Term
Pathophysiology of Hypernatremia
Definition
causes: acute rise in Na can cause water movement from ICF to ECF which can rupture cerebral veins; diabetes insipidus: decreased ADH secretion, drugs like lithium, demeclocycline, and foscarnet, CNS disorders, electrolyte abnormalities
Term
Clinical Presentation of Hypernatremia
Definition
rapid elevation causes CNS symptoms; muscle weakness, lethargy, coma; "brain shrinkage" causing cerebral bleeding & permanent neurologic damage; if hypovolemic: postural hypotension, dry mucous membranes, reduced or diluted urine output, thirst
Term
Principles of Treatment for Hypernatremia
Definition
if it develops over a few hours, reduce Na by 1 mEq/L/hr; if more insidious, reduce Na at 0.5 mEq/L/hr with target of 10 mEq/L/day; cerebral edema is a concern with overly rapid administration of hypotonic fluids; preferred route for fluids is ORAL; if giving IV, ONLY hypOtonic fluids
Term
Treatment of Pure Water Loss/Hypotonic Sodium Loss Hypernatremia
Definition
give D5W, 1/2NS; calculate water deficit: 1/2 of water deficit is replaced in 12-24 hrs with remainder over the next 24-48 hrs
Term
Treatment of Diabetes Insipidus-inspired Hypernatremia
Definition
give desmopressin (ADH analog); can also use thiazide diuretics for nephrogenic DI
Term
Treatment for Hypertonic Sodium Gain Hypernatremia
Definition
treat with D5W and furosemide to reduce volume
Term
Monitoring Parameters for Hypernatremia
Definition
if symptomatic, serum Na every 2-3 hrs on 1st day, then every 6-12 hrs; check fluid status every 8 hrs initially, then every 24 hrs
Term
Epidemiology of Hypocalcemia
Definition
occurs when serum Ca < 8.5 mEq/L; not common for oupatients, common in ICUs
Term
Parathyroid Hormone Insufficiency in Hypocalcemia
Definition
causes hypocalcemia due to pancreatitis/GI surgery
Term
Vitamin D Insufficiency in Hypocalcemia
Definition
causes hypocalcemia due to malnutrition, malabsorption, chronic kidney disease/acute renal failure, nephrotic syndrome
Term
Calcium Chelation in Hypocalcemia
Definition
causes hypocalcemia by alkalosis
Term
Other-drug Induced cause for Hypocalcemia
Definition
causes hypocalcemia: furosemide, calcitonin, bisphosphonates, cincalcet
Term
Pathophysiology of Hypocalcemia
Definition
low serum Ca --> increases PTH --> increased Ca & PO4 from bone, intestinal absorption, and reabsorption of Ca and excretion of PO4 in kidney --> Increased serum Ca
Term
Albumin levels correspond with Ca levels
Definition
Corrected Ca = measured Ca + [0.8*(4 - albumin)]
Term
Clinical Presentation of Hypocalcemia
Definition
rapidity of Ca drop correlates with severity; Neuromuscular: cramps, paresthesia, TETANY; Cardiovascular: PROLONGED QT, decreased myocardial contraction; CNS (chronic): depression, anxiety, confusion
Term
Treatment of Acute Symptomatic Hypocalcemia
Definition
bolus: 100-300 mg elemental Ca over 5-10 min; Infusion: 0.5-2 mg/kg/hr elemental Ca; Maintenance Infusion: 0.3-0.5 mg/kg/hr elemental Ca; use CaCl or CaGluconate
Term
CaCl or CaGluconate
Definition
used to treat acute symptomatic hypocalcemia & hyperkalemia; given IV; MoA: replaces deficient Ca needed for neurotransmission & muscular contraction, stabilizes cardiac membrane; ADRs: severe cardiac dysfunction if infused too fast, precipitation if added with HCO3 or PO4; Effective in replacing Ca, reverses EKG in minutes in treatment of hyperkalemia; CaCl associated with more tissue necrosis
Term
Treatment of Chronic Asymptomatic Hypocalcemia
Definition
give 1-3 gm elemental Ca per day PO; MoA: replaces deficient Ca (CaCO3, CaCitrate [more effective in elderly with reduced acidity of stomach], CaLactate); also give Vitamin D (cholecalciferol, ergocalciferol, calcitriol)
Term
Monitoring for Hypocalcemia
Definition
serum Ca q4-6 hrs during IV infusions; serum Ca q1-2 days with initiation of oral therapy; improvements of signs/symptoms
Term
Epidemiology of Hypercalcemia
Definition
serum Ca > 10.5 mg/dL; very rare
Term
Causes of Hypercalcemia
Definition
malignancy (cancers), medications (thiazides, lithium), granulomatous disorders, & miscellaneous endocrine disorders (i.e. hyperthyroidism)
Term
Pathophysiology of Hypercalcemia
Definition
many tumors release a protein similar to PTH which causes increased Ca resorption from bone & reabsorption from renal tubules
Term
Clinical Presentation of Hypercalcemia
Definition
due to malignancy: rapid onset of anorexia, nausea/vomiting, constipation; crisis: acute renal failure, obtundation (diminished level of consciousness), progress to ventricular arrhythmias; calcium or CaPhos deposits contribute to cardiac disease & heart failure
Term
Mild-moderate Hypercalcemia
Definition
total serum Ca > 13 mg/dL
Term
Hypercalcemic crisis of Hypercalcemia
Definition
serum Ca > 15 mg/dL
Term
Treatment of Hypercalcemia with EKG Changes, Neurologic Manifestations, or Pancreatitis
Definition
treat by expanding fluid volume & increasing Ca excretion with a diuretic if fluid overload (bisphosphonates are first line); pt w/ stage 4-5 CKD or severe HF: hemodialysis, NS, furosemide (Lasix); If CKD or HF: calcitonin (Miacalcin), bisphosphonates, glucocorticoids
Term
furosemide (Lasix)
Definition
used for treatment of hypercalcemia & hyperkalemia; MoA: inhibits Na/K/Ca channel in ascending loop of Henle, causing a reduction in serum Ca & K; ADRs: ototoxicity, hypokalemia; Efficacy: important to use AFTER hydration has been initiated otherwise it can increase Ca, onset K within minutes
Term
calcitonin (Miacalcin)
Definition
used to treat hypercalcemia; MoA: antagonizes effects of PTH - inhibits bone resorption & renal reabsorption causing more Ca to be excreted in urine; ADRs: allergic rxn; Efficacy: rapid onset bu unpredictable degree of Ca reduction
Term
bisphosphonates: pamidronate (Aredia), zoledronic acid (Zometa), ibandronate (Boniva)
Definition
used to treat hypercalcemia; MoA: osteonecrosis of jaw, acute renal failure; Efficacy: useful for reducing serum Ca in 48 hrs in combo with fluids & calcitonin, drug of choice for hypercalcemia of malignancy
Term
glucocorticoids: prednisone (Deltasone)
Definition
used to treat hypercalcemia; MoA: reduces calcitriol production by activated mononuclear cells, also decreases Ca absorption, increases Ca excretion, & increases bone resorption; ADRs: infection, osteoporosis, hyperglycemia; Efficacy: limited to patients with chronic granulomatous disease
Term
Treatment of Hypercalcemia in patients with less severe symptoms (muscle weakness, abdominal pain, cognitive deficits)
Definition
treat with volume expansion and diuresis
Term
Treatment of Hypercalcemia for patients that are asymptomatic
Definition
monitor and correct reversible causes
Term
Monitoring pts with Hypercalcemia
Definition
check serum Ca daily if hospitalized; signs & symptoms of hypercalcemia; fluid status/renal fcn if diuretics/fluids administered; cardiac rhythm if Ca is significantly elevated
Term
Epidemiology of Hypophosphatemia
Definition
Serum PO4 < 2.5 mg/dL; found in 1-3% of hospital admissions; severe form occurs in acute settings
Term
Etiology of Hypophosphatemia
Definition
caused by internal redistribution (refeeding syndrome/dextrose, insulin, respiratory alkalosis, alcoholism), decreased intestinal absorption (CaCO3, Sevelamer, Lanthanum, diarrhea), and increased urinary excretion
Term
Clinical Presentation of Hypophosphatemia
Definition
does not typically produce symptoms unless severe (<1 mg/dL); if severe: seizures, rhabdomyolysis, hemolysis
Term
Classification of Hypophosphatemia
Definition
mild-moderate: 1-2.5 mg/dL;
severe: < 1 mg/dL
Term
Prevention of Hypophosphatemia
Definition
for patients receiving hyperalimentation, add 12-15 mmol/L phos to prevent
Term
Treatment of Severe Hypophosphatemia
Definition
treat with IV replacement (required); use IV phosphorous (NaPhos, KPhos)
Term
IV Phos (NaPhos, KPhos)
Definition
used to treat hypophosphatemia; MoA: replaces deficient phosphorous; ADRs: hyperphosphatemia, CaPhos precipitation; Efficacy: desired response typically seen in 24 hrs
Term
Neutra-phos
Definition
ORAL, used to treat hyperphosphatemia; Na (7 mEq), K (7 mEq), Phos (8 mmol) per packet; ADR: osmotic diarrhea
Term
Neutra-phos K
Definition
ORAL, used to treat hypophosphatemia; K (14.25 mEq), Phos (Phos 8 mmol) per packet; ADR: osmotic diarrhea
Term
K-Phos Neutral
Definition
ORAL, used to treat hyperphosphatemia; Na (13 mEq), K (1.1 mEq), Phos (8 mmol) per packet; ADR: osmotic diarrhea
Term
Fleets Phospho-soda
Definition
ORAL,used to treat hyperphosphatemia; Phos (4 mmol) per mL; ADR: osmotic diarrhea
Term
Monitoring Parameters for Pts with Hypophosphatemia
Definition
severe: serum Phos q6 hrs with IV phos therapy for 48-72 hrs; mild-moderate: daily serum Phos, K, Mg, Ca
Term
Epidemiology of Hyperphosphatemia
Definition
when Phos > 4.5 mg/dL
Term
Etiology of Hyperphosphatemia
Definition
Phos intake: Phos containing laxatives/enemas; increased intestinal absorption; redistribution from ICF; decreased renal function: renal failure
Term
Clinical Presentation of Hyperphosphatemia
Definition
pt has obstructive uropathy, N/V/D, lethargy, seizures; for chronic: organ damage & osteodystrophy
Term
Classification of Hyperphosphatemia
Definition
Mild-moderate: Phos 4.6-7 mg/dL; Severe: Phos > 7 mg/dL
Term
Treatment of Severe Symptomatic Hyperphosphatemia
Definition
if hypocalcemic, IV Ca; if Ca is NOT severely low, restrict Phos intake, block additional Phos absorption: phosphate binders (CaAcetate [PhosLo], sevelamer [Renvela], lanthanum [Fosrenol], AlOH [Amphojel], MgOH [Milk of Magnesia])
Term
calcium acetate (PhosLo)
Definition
phosphate binder used to treat hyperphosphatemia; MoA: binds to phos inhibiting intestinal absorption; ADR: hypercalcemia
Term
calcium acetate (PhosLo)
Definition
phosphate binder used to treat hyperphosphatemia; MoA: binds to phos inhibiting intestinal absorption; ADR: hypercalcemia
Term
sevelamer (Renvela)
Definition
phosphate binder used to treat hyperphosphatemia; MoA: non-absorbable hydrogel that binds Phos inhibiting intestinal absorption; ADR: N/V/D, arthralgia; Efficacy: costly, beneficial effects on HDL & LDL
Term
lanthanum (Fosrenol)
Definition
phosphate binder used to treat hyperphosphatemia; MoA: binds to phos inhibiting intestinal absorption; tablet should be CHEWED; ADR: N/V/D; Efficacy: cost limits utility
Term
aluminum hydroxide (Amphojel)
Definition
phosphate binder used to treat hyperphosphatemia; MoA: binds to Phos inhibiting intestinal absorption; ADRs: anemia, CNS disorders, bone disease; Efficacy: effective
Term
magnesium hydroxide (Milk of Magnesia)
Definition
phosphate binder used to treat hyperphosphatemia; MoA: binds to Phos inhibiting intestinal absorption; ADRs: hypermagnesemia; Efficacy: safety concerns limit utility
Term
Monitoring Parameters of Hyperphosphatemia
Definition
if severe, check serum Phos bid to qd; check Ca if severe hypocalcemia
Term
Epidemiology of Hypokalemia
Definition
one of most common electrolyte disturbances; K < 3.5 mEq/L
Term
Etiology of Hypokalemia
Definition
caused by hyperaldosteronism (heart failure, cirrhosis, nephrotic syndrome, dehydration); renal tubular defects; drugs (insulin, beta-agonists, diuretics [loop & thiazide], bicarbonates; gastrointestinal (vomiting, diarrhea, malabsorption); increased losses from skin; alkalosis
Term
Clinical Presentation of Hypokalemia
Definition
Mild (K = 3-3.4 mEq/L): asymptomatic; Moderate (K = 2.5-3 mEq/L): cramping, weakening, myalgias; Severe (K = <2.5 mEq/L): ST segment & T-wave changes, many different arrhythmias
Term
Treatment of Hypokalemia
Definition
if serum K = 3-3.5 mEq/L, administer oral therapy if cardiac conduction abnormalities (KCl, KPhos, KBicarb/KCitrate); if serum K <3 mEq/L, use oral products if asymptomatic OR if symptomatic, use: IV K
Term
IV Potassium (K)
Definition
used to treat symptomatic severe (K <3mEq/L) hypokalemia; MoA: replace depleted K; Dose notes: if rate of administration is >10 mEq/hr, monitor EKG...administer up to 40 mEq/hr IV in ICU...DO NOT administer IV PUSH...concentrations >40 mEq/L can cause irritation when administered peripherally; ADRs: pain & burning at injection site; Efficacy: prepare in NS or 1/2NS
Term
KCl (K-Dur, Klor-Con, MicroK), KPhos (Neutraphos, Neutraphos K), KBicarb/KCitrate (Effer-K, KlorCon/EF)
Definition
oral products used to treat moderate hypokalemia (serum K = 3-3.5 mEq/L); ADRs: GI irritation/ulceration; Efficacy: KPhos used when Phos deficiency too, KBicarb if there is metabolic acidosis, KCl most often used
Term
Monitoring Parameters for Hypokalemia
Definition
monitor serum K after each administration of 30-40 mEq of K; K measured 30 min after IV administration; monitor q2-3 days if oral products given to hospital patients; EKG monitoring
Term
Epidemiology of Hyperkalemia
Definition
largely occur because of overcorrection of hypokalemia and renal disease
Term
Etiology of Hyperkalemia
Definition
caused by psueodhyperkalemia (hemolysis of sample); increased K intake & absorption; impaired renal excretion (acute kidney injury, chronic kidney disease, NSAIDs); hypoaldosteronism (ACEIs, aldosterone receptor antagonists); transcellular shifts (acidosis, Beta-blockers, Digitalis toxicity); cellular injury
Term
Pathophysiology of Hyperkalemia
Definition
K elevation accompanied by low HCO3 (acidosis) & elevated BUN & SCr (AKI/CKD)
Term
Clinical Presentation of Hyperkalemia
Definition
Frequently asymptomatic, ventricular arrhythmias, neuromuscular symptoms; Mild: 5.1-6 mEq/L, Moderate: 6.1-6.9 mEq/L, Severe: >7 mEq/L
Term
Treatment of Asymptomatic Hyperkalemia
Definition
restrict dietary intake; no drugs needed if mild; loop diuretics (furosemide) or binding agents (sodium polystyrene sulfonate [SPS or Kayexalate])
Term
sodium polystyrene sulfonate (SPS or Kayexalate)
Definition
binding agent used to treat asymptomatic & moderate-severe hyperkalemia; MoA: cation exchange resin (Na originally bound to resin & is substituted with K which passes through intestines); Efficacy: onset is within 1 hr, DON'T mix with OJ
Term
Treatment of Moderate Symptomatic or Severe Hyperkalemia
Definition
treat by antagonizing cardiac membrane with CaGluconate & CaCl; shift K intracellularly (dextrose/insulin therapy [Humulin R, Novolin R], NaBicarb, Albuterol); remove K from body (SPS, HD)
Term
Dextrose/Insulin Therapy (Humulin R, Novolin R)
Definition
used to treat moderate-severe hyperkalemia by shifting K intracellularly; MoA: insulin increases activity of Na/K/ATPase pump...dextrose prevents hypoglycemia; ADR: hypo/hyperglycemia; Efficacy: deemed effective by a Cochrane review
Term
NaBicarb
Definition
used to treat moderate-severe hyperkalemia by shifting K intracellularly; MoA: increases serum pH causing K shift intracellularly; ADRs: tetany, hypernatremia, fluid overload; Efficacy: useful if underlying cause is metabolic acidosis, NOT useful if pts have CKD
Term
albuterol
Definition
used to treat moderate-severe hyperkalemia by shifting K intracellularly; MoA: stimulates Na/K/ATPase pump; nebulizing solution; ADRs: tachycardia
Term
Monitoring Parameters for Hyperkalemia
Definition
in outpatients, monitor every 2-4 wks; if symptomatic, frequent EKG & K monitoring (continuous until K <5 mEq/L & EKG changes have resolved)
Term
Epidemiology of Hypomagnesemia
Definition
common electrolyte abnormality; seen in many alcoholics (30%) if hospitalized
Term
Etiology of Hypomagnesemia
Definition
caused by medications (alcohol abuse, diuretic use [TZD & loop]), renal losses, GI losses (chronic diarrhea, malnutrition), miscellaneous endocrine disorders
Term
Clinical Presentation of Hypomagnesemia
Definition
neuromuscular signs & symptoms: tetany, tremor, twitching, seizures; cardiac signs & symptoms: heart palpitations, other arrhythmias
Term
Treatment of Moderate & Severe Hypomagnesemia
Definition
treat with MgSO4 (magnesium sulfate); MoA: replenishes deficient Mg; ADRs: hypotension, vasodilation; Efficacy: works immediately as anticonvulsant, takes 3-5 days to replace deficient Mg
Term
Treatment of Mild Hypomagnesemia
Definition
manage with 4-6 grams IV per day for 5 days OR oral Mg preparations: MgOH (Milk of Magnesia) or magnesium oxide (Mag-Ox); ADRs: diarrhea; Efficacy: takes 3-5 days to replace Mg
Term
Monitoring Parameters for Hypomagnesemia
Definition
for severe: hourly Mg levels & continuous EKG until 1.8 mg/dL; mild/moderate: BID-daily Mg levels & assessment for diarrhea of oral Mg
Term
Epidemiology of Hypermagnesemia
Definition
rare electrolyte abnormality; more predisposed to critically ill pts
Term
Etiology of Hypermagnesemia
Definition
impaired renal excretion (ARF/CKD); exogenous Mg (antacids/laxatives); impaired Mg elimination; miscellaneous causes
Term
Pathophysiology of Hypermagnesemia
Definition
as ClCr descends below 30 mL/min, condition increases
Term
Clinical Presentation of Hypermagnesemia
Definition
early signs (3 mg/dL): N/V; as levels rise above 4 mg/dL: hyporeflexia, loss of deep tendon reflexes; levels of 5-6: hypotension & EKG changes; levels >9 mg/dL: respiratory depression, coma, complete heart block; levels of 10-15: asystole, cardiac arrest, death
Term
Treatment of Hypermagnesemia
Definition
treat with IV Ca products (antagonizes neuromuscular & cardiovascular effects of Mg), IV diuresis + fluids (furosemide); ESRD pts should receive emergent HD
Term
Monitoring of Hypermagnesemia
Definition
severe: Mg & Ca levels hourly & continuous EKG until asymptomatic or Mg < 4 mg/dL; moderate w/ diuresis: Mg levels BID-QID