Electrolytes: Opposites AttractBrian Dubiel RD, LD, CNSC

Disclosure

No conflict of interest exists.

Overview

• Fluids

• Electrolytes

• Causes and common treatments for electrolyte abnormalities

• Shortages

• Trends

• Case study

Water

50-60% of body= water

• age

• gender

• weight

• fat stores

Less total body water as we age

Fluid requirements

Healthy individuals

• 25-35ml/kg for normal BMI

• May elect to use ideal body weight for the obese

Individuals with high outputs and/or altered organ function should have fluids based on clinical picture.

• kidney, liver, lung, heart failure

• Short bowel, high output ostomy/ECF etc.

Body Water Compartments

Extracellular Fluid

interstitial fluid plasma

Total body water

Intracellular fluid Extracellular fluid

Serum Osmolality

• Measurement of the body electrolyte-water balance.

• Normal= 275-290mOsm/kg H20

Calculating Serum Osmolality=

(2 x serum Na) + (BUN/ 2.8)

+ (blood glucose mg/dL / 18)

Composition of common IVF

Solution Sodiummeq/L

ChlorideMeq/L

PotassiumMeq/L

LactateMeq/L

Dextroseg/L

OsmolaritymOsm/L

Normal saline (NS) 0.9%

154 154 0 0 0 290

½ NS 77 77 0 0 0 145

D5W 0 0 0 0 50 250

D5-NS 154 154 0 0 50 560

LactatedRingers (LR)

130 109 4 28 0 270

Electrolyte composition of body fluids and equivalent replacement IVF

Source Na/L K/L Cl/L HCO3/L Equivalent IVF

Urine 60 30 40 0 D5-1/2NS,20meq KCl/L

Gastric 60 10 130 0 D5-1/2NS,10meq KCl/L

Duodenum 140 5 80 0 D5-NS

Jejunum 100 5 100 10 D5-1/2NS

Ileum 140 5 104 30 D5-NS

Colon 60 30 40 0 D5-1/2NS,20meq KCl/L

Diarrhea 120 15 80 50 D5-1/2NS,25meq NaHCO3/L

Volume distribution (hypotonic fluid)1

1 liter D5W

ECF 333mL

Plasma 85mL

Interstitial 250mL

ICF 667mL

Volume distribution (Isotonic fluid)1

1 liter 0.9% NaCl

1000mL ECF

250mL plasma

750mL interstitial 0mL

ICF

Third spacing

Fluid shifts from the plasma or intravascular space to the interstitial or third space.

• Loss of oncotic and/or hydrostatic pressure

• Causing edema, effusions, ascites

Etiology• Severe inflammation, trauma, vein obstruction, intestinal obstruction, etc.

Daily Fluid Losses

• Urine 1000-1500mL

• GI tract 100-200mL

• Insensible 500-750mL (sweat, respiration)

• Factors increasing fluid losses• High stoma OP, emesis, diarrhea

• Fever

• Diuresis

• Burns

Case study

• 50 YO male with normal renal function, afebrile with high ostomy output- 2,300mL daily, 800mL oral fluid intake, 2,000mL IVF • +1,500mL for urine

• +2,300mL for stoma

• +500mL for insensible losses

• -800mL oral intake

• -2,000mL IVF

• = 1,500mL additional fluid required

Antidiuretic Hormone (ADH)

• Produced by hypothalamus

• Regulation by osmoreceptors in response to changes in osmolarity

• Hyperosmolality= ADH released, alerts kidneys to reabsorb water

• Hypoosmolality= excessive water reabsorption, suppresses ADH release.

SIADH

• Syndrome of inappropriate antidiuretic hormone• The body produces too much ADH- fluid retention

• Common causes• Stroke, lung dz, antidepressants, anti seizure meds, CA meds, etc

Hypovolemia ECF deficit

• Without electrolyte loss• Dehydration- impaired thirst, inadequate TF flushes, concentrated formula

• Treat with hypotonic fluid; D5W or increase flushes

• With electrolyte loss• GI losses, aggressive diuresis

• Results in low urinary Na+

• Release of ADH causing fluid retention and often hypoNa+2

• Treat with Isotonic fluids with electrolytes

Hypervolemia ECF expansion

• Causes• Organ failure, excessive fluid intake, anesthesia

• Symtoms• Edema, SOB, HTN, tachypnea, distended jugular, increased weight

• Tx• Water and/or sodium restriction with/without diuretic use

Sodium

• Major ECF cation

• Functions to maintain ECF volume and plasma osmolality

• Regulated by kidney for excretion and reabsorption

• 23mg=1mEq Na+

Hyponatremia

• Na+ 120 – 125: • nausea, vomiting, weakness, lethargy, headache,

• altered mental status, muscle cramping, dizziness

• Na+ < 120: seizure, coma, death

• Sodium correction should not exceed 5 to 10 mEq/kg/d to prevent demyelination disorder.

Hyponatermia

• Dilutional (most common)• Water restriction

• Hyperglycemic Pseudo-hyponatremia• Decrease of 2.4mEq/L Na+ with every 100mg/dL increase in glucose above

normal3

Hyponatremia

• Hypovolemia• Loss of body fluid and sodium

• Diuresis, excessive GI losses, sweating, burns

• Tx: Volume expansion with isotonic fluids

• Hypervolemia• Excess body fluid and total body sodium

• CHF, cirrhosis , nephrotic syndrome, renal failure, heart failure

• Tx: fluid and Na restriction, treat underlying disorder

Hypernatemia Na+ >145

• Hypovolemia• Loss of total body water

• Diarrhea, sweating, respiratory, diuresis, renal failure

• Tx: volume expansion (hypotonic fluids: .45% NS or D5W)

• Hypervolemia• Excessive/normal body fluid with excess total body sodium

• Aggressive infusion of IV NaCl or Na bicarb

• Tx: diuretics, water replacement, dialysis

Potassium 3.7-5.1mmol/L

• Major ICF Cation

• Functions with metabolism, muscle contraction, cardiac function

• 1-2mEq/kg/day with normal renal fnx

Hypokalemia <3.7mmol/L

• Causes• high gastric losses, alkalosis, hypothermia2

• Aggressive diuretics, beta-agonist bronchodilators2

• Refeeding syndrome• Dextrose infusion in malnourished pt> insulin drives K from ECF into cells5

• Symptoms• Weakness, muscle spasms, ileus, anorexia

• Tx• Replete magnesium if needed• Oral route when possible if asymptomatic • IV infusion of KCl 10-20mEq per hour2

K+ wasting medications6

• Acetazolamide

• Bumetanide

• Chlorthalidone

• Ethacrynic acid

• Furosemide

• Indapamide

• Metolazone

• Thiazides

• Torsemide

• Sodium polystyrene sulfonate

• Phenolphthalein

• Sorbitol

• Hydrocortisone

• Fludrocortisone

• Prednisone

• Caffeine

• Nafcillin

• Ampicillin

• Penicillin

• Aminoglycosides

• Amphotericin B

• Foscarnet

• Theophylline

Hyperkalemia >5.1mmol/L

• Causes • Renal failure, K+ supplementation, metabolic acidosis, meds, rhabdomyolysis

• Symptoms• Nausea, fatigue, bradycardia, mental confusion, paresthesia of extremities,

cardiac arrhythmia/arrest

• Tx• Dextrose infusion (25–100 g with 5–10 units insulin)7

• Kayexalate, loop diuretic, hemodialysis(renal failure)

• Severe hyperkalemia >7.0mmol/L• +ECG changes; 1g IV Calcium gluconate over 3 mins2

K+ sparing medication8

• ACE inhibitors

• Angiotensin recptor blockers

• Beta blockers

• Cyclosporine

• Digitalis

• Diuretics K+ sparing

• Heparin

• NSAIDs

• Pentamidine

• Penicillin

• Tacrolimus

• Trimethoprim-sulfamethoxazole

• Succinylcholine

Magnesium

• Second most abundant intracellular cation

• 8-24 mEq/day

• 1g mag = 8 mEq

• Functions

• Enzymatic reactions, including cellular energy metabolism

• Maintenance of intracellular potassium and calcium

• Bone health

• Absorption: 30 – 40% Mg absorbed in GI tract

• Distal jejunum and ileum

• Excretion: kidneys, stool

Hypomagnesemia <1.7mg/dL

• Causes• Urinary losses, alcoholism, diarrhea, refeeding syndrome, diuretics

• Symptoms• Tetany, seizures, altered mental status, arrhythmias

• Tx• Oral preparations for maintenance only2 (5mg/kg)

• Slow onset, large doses GI irritant

• IV given as mag-sulfate• 1-2g (8-16mEq) over 1-2 hours

Hypermagnesemia >2.6mg/dL

• Causes• Renal disease, excessive supplementation, excessive mag-based antacids

• Symptoms• Altered mental status, hypotension, respiratory paralysis, cardiac

arrthymia/arrest

• Tx• Diet restriction• Eliminate Mg meds/PN infusion• Use diuretics• Use IV calcium (1g IV over 2-3 minutes)9

• When severely symptomatic to reverse cardiac and neuromuscular effect

Calcium• 99% of calcium found in bone• Extracellular cation• 5-22mEq/day• Three forms of serum calcium

• Complexed to sulfate/phosphate• Protein bound (80% on albumin)• Ionized (metabolically active)

• Functions• bone health, blood coagulation, neuromuscular function, cell membrane

integrity

Hypocalcemia <8.5mg/dL

• Causes• Renal failure, hypoparathyroidism, hypomagnesemia, hyperphosphatemia• Meds aminoglycosides, cimetidine, heparin and theophylline

• Symptoms• CHF, MS changes, muscle cramps, seizures, double vision, tetany

• Measuring total serum Ca can be misleading with hypoalbuminemia• Serum Ca is decreased• Ionized Ca is not changed• Using an adjusted calcium equation is not considered accurate10

Hypocalcemia

• Tx• Replete magnesium if needed

• Asymptomatic – replete using oral route (500-1000mg) calcium citrate

• Symptomatic – replete using IV• Peripheral – 22mL of 10% calcium gluconate over 10 mins

• Central – 8mL of 10% calcium chloride over 10 mins (3x Ca content)2

Hypercalcemia >10.5mg/dL

• Causes• Hyperparathyroidism, malignancy – most common

• Meds lithium, thiazide diuretics

• Symptoms• N/V, constipation, ileus, pancreatitis, hypotension, hypovolemia, confusion

• Tx (>14mg/dL)• IV normal saline – to correct hypovolemia

• IV furosemide 40-80mg q2 hrs with NS to achieve urine OP of 100-200mL/hr2

Phosphorus

• Major intracellular anion

• Functions• Acid-base buffer, cellular & bone fnx

• Storage and transfer of energy in form of ATP

• 15-30mmol/day

Hypophosphatemia <2.7mg/dL

• Causes• Refeeding syndrome, respiratory alkalosis, DKA, phosphate binders

• Symptoms• Muscle weakness, impaired myocardial contractility, difficulty breathing,

seizure, coma

• Tx• IV sodium or potassium phosphate

• 15, 30 or 45mmol replacements over 4-6 hours (0.25-0.5 mmol/kg)

Hyperphosphatemia >4.8mg/dL

• Causes• Renal insufficiency/failure, rhabdomyolysis, tumor lysis

• Symptoms• Acute hypocalcemia, formation and deposition of insoluble Calcium

phosphate complexes into soft tissues

• Tx• Phosphate binders- aluminum containing antacids, sucralafate, Sevelamer

• Dialysis

Shortages

• KCl additives/trace element preparations for TPN• Change to K-acetate or K-phos

• MTE 5C exchanged for MTE 4C + 60 mcg selenium

• IV sodium phosphate• Oral given when possible; K-phos

• IV fat emulsion• Adults not given, rationed for peds

• 1 tablespoon safflower oil orally TID• If NPO/SBS – administered topically

Shortages

• Amino acids• Freamine III 10% Travasol 10%

• 15% 10%

• Ethanol lock• Reduce to 3 times weekly for high risk patient

• saline only for lower risk patients

Trends

• Many shortages brought on from Hurricane Maria have resolved

• Potassium Acetate supply decreased from compensation of KClshortage.

• IV famotidine potential for shortage- can be substituted with Ranitidine in TPN

Case study39 YO female with h/o stricturing Crohn’s disease and DVT with normal renal fnx. Admitted with SBO. After failing conservative management, OR for SBR with proximal diverting loop ileostomy. On POD#3, diet advanced to clear liquids after ROBF. By POD#4 the patient is noticeably more lethargic and c/o nausea.

POD#4 POD#1 Intake POD#4

Sodium 130 mEq/dl 138 mEq/dl PO 1000 ml

Potassium 3.6 meq/dl 3.9 meq/dl IVF/meds 200 ml

Chloride 104 meq/dl 96 meq/dl

CO2 23 meq/dl 26 meq/dl Output

BUN 55 mg/dl 7 mg/dl Urine 900 ml

Creatinine 1.86 mg/dl 0.9 mg/dl Stoma 3150 ml

Magnesium 1.1 mEq/dl 1.6 mEq/dl

Phosphorus 3.5 mg/dl 1.8 mg/dl

Glucose 161 mg/dl 145mg/dl

Calcium 8.7 meq/dl 8.5 meq/dl

Blood pressure 81/55 118/82

Urine sodium <20 mEq/L

Poll Question > Answer options on next slide

On assessment:

• Intake<output; oiliguirc

• Hyponatermic, hypomagnesemic

• Mildly hypotensive

•ECF loss + electrolyte loss

Which is the best IVF to use for this patient?

Answer is A; isotonic fluid will expand ECF volume

Poll question: Which electrolyte should be replaced next?

(live poll on next slide)

Answer is D; The magnesium should be repleted before potassium, and since mag is quite low, 2 grams should be

infused over 1 hour, especially when symptomatic.

References

• 1. Moukarzel A. Understanding and managing fluid and electrolyte imbalances. In A.S.P.E.N. Core Cirriculum. 2012: 99-118.

• 2. Marino P. Hypertonic and Hypotonic Conditions. The Little ICU Book of Facts and Formulas. Lippincott, Williams & Wilkins. 2009. Ch 26. 409-425.

• 3. Hillier TA. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. 1999 Apr;106(4):399-403.

• 4. Adrogue HJ, Madias NE. Hyponatremia. N Engl J Med. 2000;342(21):1581-1589.

• 5. Stanga Z, et al. Nutrition in clinical practice the refeeding syndrome: illustrative cases and guidelines. Eur J Clin Nutr. 2008;62:687-694.

• 6. Veltri K. Medication Induced Hypokalemia. P&T. 2015 Mar; 40(3): 185–190.

• 7. Kraft M, Btaiche I, Sacks G, Kudsk K. Treatment of electrolyte disorders in adult patients in the intensive care unit. Am J Health Syst Pharm. 2005;63:1663-1681.

• 8. Salem C, et al. Drug Induced Hyperkalemia. Drug Safety. Springer International Publishing. 2014. 37: 677.

• 9. Modres JP, et al. Excess Magnesium. Pharmacol Rev 1977. 29:273-300.

• 10. Slomp J, et al. Albumin-Adjusted Calcium is Not Suitable for Diagnosis of Hyper- and Hypocalcemia in Critically Ill Patients. Crit Care Med. 2003; 31: 1389-1393.

Questions?