Fluid and Electrolyte Abnormalities Dr Shreedhar Paudel April
Fluid and Electrolyte Abnormalities Dr. Shreedhar Paudel April, 2009
Water Steady State • Amount Ingested = Amount Eliminated
Body Fluids and Fluid Compartments • The percentage of total body water: 45 -75% • Intracellular compartment – 2/3 of body water (40% body weight) • Extracellular compartment – 1/3 of body water (20% body weight) • the blood plasma (water=4. 5% body weight) • interstitial fluid and lymph (water=15% body weight) • transcellular fluids: e. g. cerebrospinal fluid, aqueous humor (1. 5% BW) • Distribution of substances within the body is NOT HOMOGENEOUS
Body Water Distribution • Individual variability (lean body mass) – 55 - 60% of body weight in adult males – 50 - 55% of body weight in adult female – ~42 L For a 70 Kg man RBC PLASMA WATER 5% CELL WATER 40% 28 L Input 3 L INTERSTITIAL FLUID COMPARTMENT 15% ECF 20% 10 L TRANSCELLULAR WATER 1% 1 L 14 L
Goals • Review of common electrolyte abnormalities – Normal ranges – Clinical manifestations of hypo- or hyper- states – Causes – Treatment options
Hyponatremia • Sodium: Normal 135 – 145 m. Eq / L • Symptoms usually begin <120 m. Eq/L – Nausea – Lethargy – Muscle cramp – Psychosis – Seizure – Coma – Death
Hyponatremia • Diagnosis based on assessment of serum osmolality and volume status • Serum Osmolality – Osmolality (calculated) = 2 (Na) + Glucose / 18 + BUN /2. 8
Hyponatremia • Normal Osmolality (280 – 295 m. Osm / kg) • Isotonic pseudohyponatremia • Hyperproteinemia (>10 mg / dl) • Hyperlipidemia (severe)
Hyponatremia • High Osmolality (>295 mosm / kg) • Hypertonic hyponatremia – Hyperglycemia Na: 1. 6 m. Eq / liter decrease per 100 mg/dl increase in glucose --Mannitol excess --Glycerol therapy
Hyponatremia • Low serum osmolality (<280 m. Osm / kg) • Hypotonic hyponatremia --Need to assess volume status next in these patients
Hypotonic hyponatremia • Hypovolemia – GI losses – Renal losses plus excess water ingestion – Third space losses Tx: Isotonic saline
Hypotonic Hyponatremia • Hypervolemia – CHF – Liver disease – Nephrotic syndrome – CKD Urine Na: < 20 m. Eq /liter except in CKD Tx: Salt restriction / water restriction / diuretics
Hypotonic Hyponatremia • Isovolemia – Glucocorticoid insufficiency – Hypothyroidism – Psychogenic polydipsia – Medications (amitriptyline / cyclophosphamide / carbamazepine / morphine) – SIADH – Nausea / pain / emotional stress – Diuretic use with potassium depletion
Isovolemic Hypotonic Hyponatremia • SIADH – Syndrome of inappropriate antidiuretic hormone • Hypotonic hyponatremia • Clinical euvolemia • Inappropriately elevated urine osmolality (>200) in face of low serum osmolality • Urine Na >20 m. Eq / liter • Normal renal function / TSH / cortisol
SIADH • Acute tx – Severe hyponatremia (<110 m. Eq / liter) • NS with 20 – 40 m. Eq / liter KCL • IV lasix • Rarely 3% saline will be needed • Chronic tx – Mild hyponatremia • Water restriction to approx 1000 ml / day • Demeclocycline 300 mg PO bid if water restriction not working (contraindicated in liver disease)
SIADH • Chronic treatment (cont) – Vasopressin receptor antagonists • Conivaptan (Vaprisol) IV prep – 20 mg infusion over 30 min, then continuous infusion of 20 mg/24 hrs – Maximum dose 40 mg/24 hrs – Maximum duration is 4 days
Hyponatremia • How fast do we correct it?
Hyponatremia • Treatment principles – Not too fast (pontine myelinolysis) • Symptomatic – Initial 1 - 2 m. Eq / L / hr x two hours, then – 0. 5 m. Eq / L / hr • Asymptomatic – 0. 5 m. Eq / L / hr – Max in 24 hours: 10 meq total rise – Max in 48 hours: 18 meq total rise
Hypernatremia • Sodium: Normal 135 – 145 m. Eq / l • Clinical manifestations – Tremors – Irritability – Ataxia – Spasticity – Mental confusion – Seizures – Coma – Death
Hypernatremia • Cause: – Net sodium gain – Net water loss
Hypernatremia • Volume expansion (net sodium gain) – Cause • Hypertonic saline / Na. HCO 3 administration • Primary hyperaldosteronism • Cushing’s syndrome Tx: Diuretics D 5 W to replace fluid loss after diuretics
Hypernatremia • Water depletion – Hypotonic fluid losses Condition Urine vol Urine osm GI / Insensible loss Low High Renal High loss Diabetes High Insipidus High Low
Hypovolemic hypernatremia • Treatment – Calculate free water deficit • TBW (liters) = 0. 6 x current total body weight (kg) • Desired TBW (liters) = Measured Na (m. Eq/l) x current TBW / Normal Na • Body water deficit (liters) = Desired TBW – current TBW
Hypovolemic hypernatremia • If hemodynamic compromise, then replace initially with NS • Otherwise use ½ NS or D 5 W – Aim to decrease Na by 0. 5 m. Eq / liter / hr – Correct one half of the water deficit in 24 hrs – Correct other half over next 24 -48 hours
Hypovolemic hypernatremia • Diabetes insipidus Sxs: Polyuria / Polydipsia / Low urine osm – Central • Tumor / Granuloma / Trauma / Surgery – Nephrogenic • Severe hypokalemia / hypercalcemia / CKD / Drugs (lithium / demeclocycline / amphotericin)
Hypovolemic hypernatremia • DI – Differentiation of central and nephrogenic • Trial of water deprivation • Failure to concentrate urine confirms DI • Subsequently given arginine vasopressin – Central DI (urine concentration increases) – Nephrogenic DI (no increase)
Hypovolemic hypernatremia • DI – Treatment • Central – Vasopressin 5 -10 mcg intranasally per day / bid • Nephrogenic – Correction of underlying cause if possible – Thiazide diuretic / salt restriction can help
Hypokalemia • Normal K level: 3. 5 – 5. 0 MEq/L • Clinical manifestations – Fatigue – Cramps – Constipation – Weakness / Paralysis – Parasthesias – Arrhythmias
Hypokalemia • EKG abnormalites – Flattened T waves – ST depressions – Prominent U waves
EKG Changes in Hypokalemia
Hypokalemia • Causes – GI losses – Renal losses – Acid-base shifts
Hypokalemia Treatment • Oral therapy – Mild hypokalemia – Ability to tolerate oral replacement – Increase dietary intake • Potatoes / Bananas – KCl preparations • Can be used in range 8 – 20 m. Eq/L • Monitor K level and adjust dose as needed • Correct cause
Hypokalemia Treatment • IV repletion – Severe hypokalemia – Inability to tolerate oral repletion Max Concentration: 60 m. Eq / liter Rate: 10 m. Eq / hr Monitor response and decrease concentration or rate as appropriate.
Hyperkalemia • Potassium Normal 3. 5 – 5. 0 – Elevated potassium level should be evaluated as to the following: • What is the cause? • Is the cause an acute or chronic issue? • Are there accompanying EKG changes?
Hyperkalemia • Symptoms – Usually asymptomatic – Muscle weakness / paralysis – EKG abnormalities • • • Peaked T waves ST depression 1 st degree AVB QRS widening “Sine wave sign”
Hyperkalemia • EKG changes
Hyperkalemia • Think about the cause • 1. Too much total potassium – Renal disease – Intake increased (rare outside of renal disease) • 2. Shift of potassium from intracellular space to extracellular space – DKA
Hyperkalemia • Does the potassium level make sense in the patient? Pseudohyperkalemia
Hyperkalemia • When do we treat – Patient assessment • Cause • Chronicity – Degree of potassium elevation • <6. 0 Does not need acute invasive tx • >6. 0 - 6. 5 Kayexalate +/- other modalities • >6. 5 Consider more acute modalities
Hyperkalemia • Treatment options – Calcium gluconate – Regular insulin – Albuterol nebulizer treatment – Na. HCO 3 – Kayexalate – Dialysis
Hyperkalemia • Calcium gluconate – IV formulation is 1000 mg / 10 ml (10% soln) – Dose: – Action: Stabilization of cardiac cells. Does not lower potassium. Used for hyperkalemia with EKG changes. – If EKG changes do not immediately resolve, dose can be repeated in 5 minutes.
Hyperkalemia • Calcium gluconate – Precautions • Do not infuse with bicarbonate (precipitation of calcium carbonate) • Do not use routinely with digitalis as hypercalcemia can augment digitalis toxicity. Limit use to patients with widened QRS.
Hyperkalemia • Beta agonist – Albuterol nebulizer treatment • 2 -4 ml of 0. 5% soln (10 -20 mg dose) • Note a usual nebulizer tx for RAD is 2. 5 mg • Peak effect in 90 minutes
Hyperkalemia • Insulin – Regular insulin 10 units IV plus one D 50 Amp over 5 minutes. This will give patient 25 grams of glucose. – Follow this with a D 5 containing IV maintenance fluid for several hours. – Effect within 15 minutes. Peak effect 60 min. Duration 3 -4 hours.
Hyperkalemia • Na. HCO 3 – 1 Amp (44. 6 meq) IV over 5 minutes. – Onset: 30 minutes – Duration: 60 -120 minutes
Hyperkalemia • Kayexalate (Na – K exchange resin) – PO dosing: 15 -30 gram • Can be used as a dry powder • Can be mixed with 60 -120 ml of a 20% sorbitol soln to avoid constipation – PR dosing: 50 grams • Mix with 50 ml of 70% sorbitol and 100 ml tap H 20 • Retain in rectum x 30 minutes minimum but ideally 2+ hours
Hypocalcemia • Normal Calcium: 8. 9 – 10. 3 mg/dl • Calcium – 40% bound to albumin – 15% bound to other serum anions – 45% is ionized in serum
Hypocalcemia • Correct for low albumin • 0. 8 mg / dl drop in Calcium for every 1 g / dl drop in Albumin • Corr Ca = Meas Ca + (0. 8 * (4. 5 – Meas Alb))
Hypocalcemia • Clinical signs of low calcium: – Tetany / Carpopedal spasm – Trousseau’s sign – Chvostek’s sign – Lethargy / confusion – Seizures – Heart failure
Hypocalcemia • Treatment of symptomatic cases – Calcium gluconate (10% soln) which contains 100 mg elem calcium / 10 ml. 1. Give two ampules IV over 10 minutes then 2. Add six ampules to 500 ml D 5 W and infuse at 1 mg / kg / hr
Hypocalcemia • Asymptomatic – Calcium orally (1000 mg / day) – Vit D orally • Calcitriol 0. 25 – 0. 5 mcg / day
Hypocalcemia • Magnesium can be effective as well – Magnesium sulfate 2 gram IV bolus followed by 1 gram / hr gtt
Hypercalcemia • Calcium range: 8. 9 – 10. 3 mg / dl
Hypercalcemia • Symptoms – Anorexia – N/V – Constipation – Polyuria – Nephrolithiasis – Weakness – Confusion – Coma – EKG: Shortened QT interval
Hypercalcemia • Causes – – – – – Primary hyperparathyroidism Malignancy Sarcoidosis Vitamin D toxicity Hyperthyroidism Thiazide diuretics Milk-alkali syndrome Renal failure Familial hypocalciuric hypercalcemia Immobilization
Hypercalcemia • Treatment – Increase urinary excretion – Diminish bone resorption – Diminish GI absorption – Chelation of ionized Ca (EDTA) – Dialysis
Hypercalcemia • Treatment: – Increase urinary excretion • NS @ 200 – 300 ml / hr to achieve UO = 100 ml /hr • Lasix (if fluid overloaded state exists)
Hypercalcemia • Treatment – Decrease bone resorption • Calcitonin 4 units SQ or IM q 12 hours – This approach works rapidly (4 hrs) and lowers Ca by 1 -2 mg / dl – Tachyphylaxsis develops after 48 hours – Note that nasal dosing does not lower calcium
Hypercalcemia • Treatment (Decrease bone resorption) – Bisphonates • Zoledronic Acid • Pamidronate
Hypercalcemia • Treatment: – Decreased oral absorption (Need in sarcoid) • Oral phosphate administration • Prednisone
Hypercalcemia • Treatment – Dialysis • Consider in severe case • Ca 18 -20 mg / dl
Hypomagnesemia • Normal: Magnesium 1. 7 – 2. 4 mg / dl
Hypomagnesemia • Think about hypomagnesemia in the following situations: – Alcoholism – Hypokalemia – Hypocalcemia – Chronic diarrhea – Ventricular arrhythmias
Hypomagnesemia • Differentiate urinary from GI losses • Fe. Mg = (Ur. Mg * PCr) *100 (0. 7*PMg*UCr) <2% = GI loss >2% = Renal loss
Hypomagnesemia • Treatment – Severe (<1. 0) • IV Magnesium sulfate 2 grams IV over 1 hr – Mild – moderate • PO Magnesium – Magnesium chloride (Slo-Mag) 2 tabs PO q day – Magnesium oxide (Mag-Ox 400) 2 tabs PO q day
Hypermagnesemia • Magnesium: Normal range 1. 7 -2. 4 • Seen in renal failure with concomitant tx with magnesium containing antacids / laxatives • Seen in preeclampsia treated with Magnesium sulfate • Notable if Mg >4. 0
Hypermagnesemia • Treatment – Stop the exogenous magnesium – HD may be needed in the setting of renal failure – Calcium gluconate (10%) 1 -2 ampules IV can be given as a bridge to setting up dialysis
Hypophosphatemia • Phosphorus: Normal 2. 6 -4. 5 mg / dl • Causes – Hyperglycemic states – Alcoholism – Respiratory alkalosis – GI abns – Alum / Mg containing antacids – Hyperparathyroidism – Renal wasting
Hypophosphatemia • Treatment – Treat underlying cause – Replete if severely low • Below 1 mg / dl in DKA – IV KPhos – PO Neutraphos
Hyperphosphatemia • Phosphorus: Normal 2. 6 – 4. 5 mg /dl • Causes: – Renal failure – Hypoparathyroidism – Rhabdomyolysis – Tumor lysis syndrome – Acidotic states – Exogenous admin of phosphorus
Hyperphosphatemia • Treatment: – Dietary restriction 0. 6 – 0. 9 grams / day – Oral phosphate binders • Calcium acetate 2 tabs PO q AC • May need to add aluminum containing product (aluminum hydroxide) – Dialysis
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