Electrolyte Abnormalities

Teresa Lianne Beck, MD Assistant Professor Emory Family Medicine August 4, 2011

Goals

 Review of common electrolyte abnormalities  Normal ranges  Clinical manifestations of hypo- or hyper states  Causes  Treatment options

Goals

 What will spend time on today…  Sodium  Potassium  Calcium  Magnesium  Phosphorus

Hyponatremia

 Sodium: Normal 135 – 145 mg / dl  Symptoms usually begin <120 mg /dl  Nausea  Lethargy  Muscle cramps  Psychosis  Seizure  Coma  Death

Hyponatremia

 Diagnosis based on assessment of serum osmolality and volume status

Hyponatremia

 Serum Osmolality  Osmolality (calculated) = 2 (Na) + Gluc / 18 + BUN /2.8

Hyponatremia

 Normal Osmolality (280 – 295 mOsm / kg) Isotonic pseudohyponatremia Hyperproteinemia (>10 mg / dl) Hyperlipidemia (severe)

Hyponatremia

 High Osmolality (>295 mosm / kg) Hypertonic hyponatremia Hyperglycemia Na: 1.6 mEq / liter decrease per 100 mg/dl increase in glucose Mannitol excess Glycerol therapy Am J Med 1999 Apr;106(4):399-403

Hyponatremia

 Low serum osmolality (<280 mOsm / 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 mEq /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 mEq / liter  Normal renal function / TSH / cortisol

SIADH

 Acute tx  Severe hyponatremia (<110 mEq / liter)   IV lasix NS with 20 – 40 mEq / liter KCL  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 gtt of 20 mg/24 hrs Maximum dose 40 mg/24 hrs gtt Maximum duration is 4 days

Hyponatremia

 How fast do we correct it?

Hyponatremia

 Treatment principles  Not too fast (pontine myelinolysis)  Symptomatic   Initial 1 - 2 mEq / L / hr x two hours, then 0.5 mEq / L / hr  Asymptomatic   0.5 mEq / L / hr Max in 24 hours: 10 meq total rise  Max in 48 hours: 18 meq total rise Am J Med. 2007 Nov;120(11 Suppl 1):S1-21.

Hypernatremia

 Sodium: Normal 135 – 145 mg / dl  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 / NaHCO3 administration   Primary hyperaldosteronism Cushing’s syndrome Tx: Diuretics D5W to replace fluid loss after diuretics

Hypernatremia

 Water depletion  Hypotonic fluid losses Condition

GI / Insensible loss

Renal loss Diabetes Insipidus Urine vol Low High High Urine osm High High Low

Hypovolemic hypernatremia

 Treatment  Calculate free water deficit  TBW (liters) = 0.6 x current total body weight (kg)  Desired TBW (liters) = Measured Na (mEq/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 D5W  Aim to decrease Na by 0.5 mEq / 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  DDAVPP 5-10 mcg intranasally q day / bid  Nephrogenic  Correction of underlying cause if possible  Genetic abnl / lithium / hypercalcemia  Thiazide diuretic / salt restriction can help

Hypokalemia

 Normal K level: 3.5 – 5.0

 Clinical manifestations  Fatigue  Cramps  Constipation  Weakness / Paralysis  Paraesthesias  Arrhythmias

Hypokalemia

 EKG abnormalites  Flattened T waves  ST depressions  Prominent U waves http://www.merck.com/media/mmpe/figures/MMPE_12END_156_02_eps.gif

Hypokalemia

 Causes  Inadequate intake  GI losses  Renal losses  Acid-base shifts  Hypomagnesemia  Hyperaldosterone  Medications (diuretics)

Hypokalemia Treatment

 Oral therapy  Mild hypokalemia  Ability to tolerate oral replacement  Increase dietary intake  Potatoes / Bananas  KCl preps (i.e. KDur)  Preps can be used in range 8 – 20 mEq  Monitor K level and adjust dose as needed  Correct cause

Hypokalemia Treatment

 IV repletion  Severe hypokalemia  Inability to tolerate oral repletion Max Concentration: 60 mEq / liter Note pain is common at > 40 mEq /liter Rate: 10 mEq / hr (20 mEq / hr with tele) Monitor response and decrease conc / 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 (hemolysis)

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  NaHCO3  Regular insulin  Albuterol nebulizer treatment  Kayexalate  Dialysis

Hyperkalemia

 Calcium gluconate  IV formulation is 1000 mg / 10 ml (10% soln)  Dose: 10 ml over 2-5 minutes IV with EKG monitoring  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  Epinephrine IV infusion  0.05 mcg / kg / min IV infusion  Peak effect in 30 minutes 

I would be hesitant to use this when an albuterol neb is easy and less risky.

Hyperkalemia

 Insulin  Regular insulin 10 units IV plus one D50 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

 NaHCO3  1 Amp (44.6 meq) IV over 5 minutes.

 Onset: 30 minutes  Duration: 60-120 minutes

Hyperkalemia

 Alternate approach to NaHCO3 / Insulin:  Put 2 Amps NaHCO3 in 1 liter D10 W.

 Give 300 ml over first 30 minutes, then change to 250 ml / hr until finished.

 Give Regular insulin 25 units SQ with starting the IVF.

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 H20  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  EKG: Prolonged QT

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 D5W 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  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

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)  Bisphosphonates  Zoledronic Acid  Hyperglycemia of malignancy  Dose: 4 mg IV over 15 minutes  Onset 2-4 days (use saline or calcitonin initially)  Effect is longlasting (several weeks)  88% pts normalized calcium  Can be repeated q 1-4 weeks as needed  Pamidronate  Alternative  Dose: 60-90 mg IV over 2 hours

Hypercalcemia

 Treatment  Decreased oral absorption (Need in sarcoid)  Oral phosphate administration  Prednisone

Hypercalcemia

 Treatment  Sensipar (cinacalcet)  Calcimimetic indicated for secondary hyperparathyroidism in ESRD  Parathyroid carcinoma  Dialysis  Consider in severe cases  Ca 18-20 mg / dl

Hypomagnesemia

 Normal: Magnesium 1.7 – 2.4 mg / dl  Symptoms  Neuromuscular irritability  CNS hyperexcitability  Cardiac arrhythmias

Hypomagnesemia

 Think about hypomagnesemia in the following situations:  Alcoholism  Hypokalemia  Hypocalcemia  Chronic diarrhea  Ventricular arrhythmias

Hypomagnesemia

 Differentiate urinary from GI losses  FeMg = (UrMg * 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  Symptoms  Weakness  Respiratory insufficiency or myocardial depression  Neurologic symptoms may vary, ranging from simple paresthesias to profound alterations in mental status

Hypophosphatemia

 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  Symptoms (due to hypocalcemia): CNS hyperexcitability, CV  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  Sevelamer (Renegal) 800 mg PO q AC  May need to add aluminum containing product (aluminum hydroxide)  Dialysis