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Diagnosis and Management of Common Electrolyte Disorders Eric I. Rosenberg, MD, MSPH, FACP Rev 11/06 electrolytes1106.

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Presentation on theme: "Diagnosis and Management of Common Electrolyte Disorders Eric I. Rosenberg, MD, MSPH, FACP Rev 11/06 electrolytes1106."— Presentation transcript:

1 Diagnosis and Management of Common Electrolyte Disorders Eric I. Rosenberg, MD, MSPH, FACP Rev 11/06 electrolytes1106

2 2 Objectives To discuss diagnostic and therapeutic strategies for: 1.Hyponatremia 2.Hypernatremia 3.Hyperkalemia 4.Hypokalemia

3 3 Case 1 60 year old man Admit for weakness and hyponatremia [Na + ] 120 mg/dL

4 4

5 5 Clinical Evaluation History –Symptomatic? –Predisposed? –Medications? IVFs? Physical –Volume status? Labs –Confirm (if unusually abnormal) –Context –Additional diagnostic tests

6 6 Case 1 (contd) Nausea, weak, confused x 1 week HTN, CHF JVD, crackles (rales), edema –Na mEq/L –BUN 93 mg/dL –Cr 3 mg/dL –Glucose 135 mg/dL –Albumin 2.9 mg/dL –Plasma osm 252 mOsm/kg –Urine osm 690 mOsm/kg

7 7 Choose the most appropriate treatment 3% I.V. NaCl 0.9% I.V. NaCl 50 mg hydrochlorothiazide daily Salt and water restriction Demeclocycline

8 8 Differential diagnosis

9 Hyponatremia usually reflects excessive H 2 0

10 10 Common Differential Dx Decreased Water Excretion GFR Kidney perfusion –SIADH Addisons Disease Malnutrition *Pseudohyponatremia ±Psychogenic (>1 L / hour) *100mg/dL glucose increase 1.6 mEq/L [Na] decrease ± Urine specific gravity < 1.003

11 11 COMMON CAUSES of HYPONATREMIA 1.History: predisposing features 2.Exam: volume status (including orthostatics supine/standing) 3.BMP; Urinalysis; Serum Osmolality; (Urine Sodium; Urine Osmolality) 4.Head C.T. (if symptomatic) 5.Other imaging/labs to evaluate CV, Renal, Endocrine systems as needed

12 12 Complications of Treating Hyponatremia Delayed treatment –Cerebral edema –Permanent neurological injury –Death Inappropriately rapid treatment –Cerebral dehydration/demyelination –Permanent neurological injury –Death Inappropriate treatment –Failure to improve morbidity –Delayed improvement morbidity –Further deterioration

13 13 Common Treatment Options Water restriction Diuresis (with loop diuretic) Volume infusion (with crystalloid) Hypertonic saline Demeclocycline

14 14 What if he had cerebral edema? 1.Correct [Na + ] to mEq/L to temporarily relieve edema 2.[Na + ] should NOT increase by more than mEq/L in 1 st 24 hours 3.Slow/Stop infusion as soon as symptoms improve

15 15 3% NaCl Calculation [Na + ] = 116 mEq/L Goal [Na + ] = 125 mEq/L at 24 hours Amount of Na + to be given as 3% infusion: = [Serum Na + (desired) – Serum Na + (measured) ] (TBW) = [125 – 116] [(0.5)(60kg)] = 270 mEq Na + 3% saline = 513 mEq sodium/L 270/513 = 0.5 L = 500 ml over 24 hrs.

16 16 Hyponatremia: Key Points 127 mEq/L Excess water If symptomatic, treat rapidly Slowly correct [Na + ] *towards* normal Find the underlying cause

17 17 Case 2 40 y/o woman s/p hypertensive brain hemorrhage 2 weeks ago. This morning shes less responsive. What may have caused this new problem?

18 18 Stuporous BP 150/70, HR 94 Dry mouth, poor turgor Na 160 mEq/L; K 2.8 mEq/L; HCO3: 18 mEq/L; Cl 137 mEq/L

19 19 Differential diagnosis

20 Hypernatremia usually reflects insufficient H 2 0

21 21 Differential Diagnosis Lack of water Severe diarrhea Severe burns H 2 0 excretion –Osmotic diuresis H 2 0 conservation –Diabetes insipidus

22 22 Guidelines for Hypernatremia Rx Determine and treat likely cause(s) Most common error is underguesstimation of water deficit: TBW x ([Na + (measured) ] – [Na + (desired) ])/[Na + (desired) ] Replace H 2 0 enterally if possible Frequent monitoring

23 23 Sodium Content of IVFs (mEq/L) 3% saline: % (normal) saline: 154 Ringers Lactate: 130 Half Normal (0.45%) saline: 77 5% Dextrose (D5W): 0

24 24 Hypernatremia: Key Points [Na + ] >145 mEq/L Net water loss Calculate the water deficit

25 25 Case 3 29 y/o man with severe muscle weakness. No vomiting or diarrhea. Normal physical exam.

26 26 Na = 141 mEq/L K = 1.4 mEq/L Cl = 116 mEq/L HCO 3 - = 11 mEq/L pH = 7.25, pCO2 = 21 mmHg

27 27 Consequences of Hypokalemia [K] <3 Neuromuscular manifestations –Weakness, fatigue, rhabdomyolysis, myonecrosis, respiratory failure GI symptoms –Constipation, ileus Nephrogenic Diabetes Insipidus Dysrhythmias (if heart disease)

28 28 Common Causes of Hypokalemia Malnutrition/NPO Diarrhea (100 mEq/L) Vomiting (volume depletion) DRUGS –Thiazides (stimulate excretion) –Amphotericin B –Penicillins –Gentamicin –Foscarnet

29 29 Choose the most likely diagnosis Bartters syndrome Laxative abuse Primary aldosteronism Diuretic abuse Distal renal tubular acidosis

30 30 Less Common Causes Hormonal –Primary hyperaldosteronism Adenomas, hyperplasia, ectopic ACTH, ectopic mineralocorticoid (licorice, chaw) –Secondary hyperaldosteronism Renal hypoperfusion (CHF, RAS, severe HTN) Renin-secreting tumor Renal tubular disease –Type 1 or 2 RTA –Bartters syndrome (metabolic alkalosis, polyuria) –Chronic magnesium depletion Laxative abuse (metabolic alkalosis)

31 31 Hypokalemia Rx Recognize likely total body depletion –1 mEq/L decrease = mEq total deficiency Gradual oral replacement I.V. replacement if serum level less than 3 mEq/L Check & Replace magnesium Consider telemetry

32 32 Hypokalemia: Key Points [K + ] < 3.5: review medications, review health status [K + ] < 3: intervention Recognize Mg+ is cofactor Renal/CV monitoring

33 33 Case 4 59 y/o man with 3-days malaise, decreased mental acuity and responsiveness, slurred speech. ESRD on hemodialysis; HTN, DM, Hypothyroidism

34 34 Disoriented and lethargic BP (supine) 148/79mmHg, HR 101/min (supine) RR 26/min, T 37.7 o C. Mucous membranes are moist, neck veins are distended. Bilateral crackles and wheezes. Loud S4. 3+ peripheral edema.

35 35

36 36

37 37 What is the next most appropriate step in managing this patient? A.Begin I.V. infusion of normal saline for volume repletion B.Administer 1 ampule dextrose and 10 units insulin I.V. for hyperkalemia C.Transfer to the ICU and perform emergent peritoneal dialysis D.Transfer to the ICU and perform emergent hemodialysis

38 Dialysis machine available in 20 minutes

39 39 Emergency Treatment [K] > 6 mEq/L STAT ECG STAT repeat [K + ] Give IV Calcium

40 40 Additional Rx More IV Calcium Glucose and Insulin Bicarbonate Inhaled Beta-2 agonists Sodium polystyrene sulfonate (Kayexalate®)

41 Severe hyperkalemia is usually preceded by moderate, uncorrected hyperkalemia

42 42 Renal Failure (GFR < 10 ml/min) Extra Renal Causes –Metabolic acidosis –Cell lysis (chemotherapy, trauma) –Salt substitutes, ACE-I/ARB, –Addisons Disease –Pseudo (coagulated RBCs/platelets) Differential Dx

43 43 Hyperkalemia: Key Points K>4.5: caution with medications, & monitor K>5.5: intervene Calcium (not kayexalate) is 1 st line Check ECG

44 44 SUMMARY Construct your differential Know the complications of therapy Know the implications of lack of therapy Calculate water/electrolyte needs … But repeated and frequent monitoring is most important. Electrolyte disorders may be a diagnostic clue or an expected consequence of therapy


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