This document discusses electrolyte disorders and provides information on hyponatremia, hypernatremia, hypokalemia, and hyperkalemia. It defines each condition, describes signs and symptoms, discusses causes and diagnostic approaches, and outlines treatment strategies. Key points covered include plasma concentration thresholds for each disorder, mechanisms of generation, common signs seen in different organ systems, diagnostic testing to distinguish causes, and methods for correcting imbalances and replacing electrolytes.

1. ELECTROLYTE DISORDERS CRISBERT I. CUALTEROS, MD http://crisbertcualteros.page.tl

2. HYPONATREMIA Plasma concentration < 135 meq/L

3. Generation of Hyponatremia Plasma Na = Na + K/ TBW

4. Sign and Symptoms Lethargy, Apathy Disorientation Muscle cramps Anorexia Nausea Agitation

5. Sign and Symptoms Abnormal sensorium Depressed deep tendon reflexes Cheyne-Stokes respiration Hypothermia Seizures

6. Diagnostic Approach Hyponatremia Na and Water Deficit Water Excess Na and Water Excess Hypervolemia Hypovolemia Euvolemia

7. Diagnostic Approach Hyponatremia Hypovolemia Euvolemia Hypervolemia Renal Losses Diuretic excess Mineralcorticoid Deficiency Salt losing nephritis RTA Extrarenal Losses Vomiting Diarrhea Burn Pancreatitis Peritonitis Urine Na >20 Urine Na<10

8. Diagnostic Approach Hyponatremia Hypovolemia Euvolemia Hypervolemia Glucocorticoid Deficiency Hypothyroidism Pain Emotional Stress Drugs SIADH Urine Na >20

9. Diagnostic Approach Hyponatremia Hypovolemia Euvolemia Hypervolemia Nephrotic Syndrome Cardiac Failure Cirrhosis ARF CRF Urine Na <10 Urine Na >20

10. Treatment Na deficit = 0.5 x wt (kg) x (D Na – A Na ) Calculation of Desired Negative Water Balance TBW = Wt (kg) x 0.6 Actual plasma Na x TBW Desired plasma Na TBW-Desired TBW = fluid to be removed

11. Rate of Correction First 24 hours = 10 -12 mEq/day Seizure and Neurologic symptoms 1.5 – 2 mEq/L/h for 3 to 4 hours

12. Central Demyelinating Lesion Paraparesis Quadriparesis Dysarthria Dysphagia Coma

13. Risk Factor for Demyelination More than 25 mEq/L elevation of Na within the first 48 hours Overcorrection of plasma Na above 140 mEq/L

14. HYPERNATREMIA Plasma Na > 150 mEq/L

15. Generation of Hypernatremia Plasma Na = Na + K/TBW

16. Sign and Symptoms Lethargy Weakness Irritability Twitching Seizures Coma Death

17. Diagnostic Approach Hypernatremia Na and H2O Deficits H2O losses Na Addition Excess Hypovolemia Euvolemia Hypervolemia

18. Diagnostic Approach Hypernatremia Hypovolemia Euvolemia Hypervolemia Renal losses Osmotic and loop diuretics Post obstruction Extrarenal Losses Sweating Burns Diarrhea Urine Na >20 Urine Na <10

19. Diagnostic Approach Hypernatremia Hypovolemia Euvolemia Hypervolemia Renal Losses Nephrogenic DI Central DI Extrarenal Losses Respiratory and Dermal Incensible Losses Urine Na = Variable Urine Na = Variable

20. Hypernatremia Hypovolemia Euvolemia Hypervolemia Primary Hyperaldoteronism Cushing’s Syndrome Hypertonic Dialysis Hypertonic NaHCO3 NaCl tablets Urine Na >20 mEq/L

21. Treatment Correction of ECF Volume Depletion Isotonic Saline Until the ECF volume is achieved Followed by Hypotonic NaCl or 5% glucose solution

22. Treatment Correction of ECF Volume Expansion Diuretics or Dialysis

23. Water Replacement Computation TBW = Wt (Kg) x 0.6 Actual plasma Na x TBW Desired plasma Na

24. HYPOKALEMIA Plasma K < 3.0 mEq/L

25. Sign and Symptoms Cardiac Atrial and ventricular ectopic beats Abnormal EKG Flat T mave Prominent U wave

26. Sign and Symptoms Neuromuscular Constipation, Ileus Weakness, paralysis Respiratory paralysis Rhabdomyolysis

27. Sign and Symptoms Renal Impaired concentrating ability (polyuria, polydipsia) Increase renal NH3 production Impaired urinary acidification Metabolic alkalosis

28. Causes Hypokalemia due to Redistribution Alkalosis Insulin excess Beta-adrenergic agonist Hypokalemic periodic paralysis

29. Causes Extrarenal Loss Diarrhea GI fistula Laxative abuse Profuse sweating

30. Causes Renal Loss Hypertensive Disorder Malignant hypertension Renovascular hypertension Renal secreting tumors Primary Aldosteronism Cushing’s Syndrome Congenital adrenal hyperplasia

31. Causes Renal Loss Normotensive RTA Vomiting Diuretics Mg depletion Barter’s syndrome Gittleman’s syndrome

32. Diagnostic Approach Hypokalemia Redistribution Extrarenal U K <20 Renal loss U K >20 Metabolic acidosis Diarrhea GI fistulas Laxative abuse Normal Acid-Base Profuse sweating Laxative abuse Gastric fistula Previous vomiting

33. Diagnostic Approach Hypokalemia Redistribution Extrarenal Loss U K <20 Renal Loss U K >20 Hypertensive High Plasma Renin Malignant HPN Renovascular HPN Renin secreting tumors Low Plasma Renin Primary Aldosteronism Cushing’s Syndrome Adrenal hyperplasia

34. Diagnostic Approach Hypokalemia Redistribution Extrarenal Loss U K <20 Renal Loss U K >20 Normotensive Metabolic Alkalosis U Cl <10 Vomiting U Cl >10 Diuretics Mg Depletion Barter syndrome Gittleman syndrome

35. Diagnostic Approach Hypokalemia Redistribution Extrarenal Loss U K <20 Renal Loss U K >20 Normotensive Metabolic acidosis Normal Anion Gap RTA Increase Anion Gap Diabetic Ketoacidosis Ethylene Glycol

36. Treatment Potassium Deficit 4.0 to 3.0 mEq/L = loss of 200 to 400 mEq/L 3.0 to 2.0 mEq/L = additional 200 to 400 mEq/L loss

37. Treatment Rate of Repletion 3.0 – 3.5 mEq/L = oral KCL 60-80 mEq/day <2.5 mEq/L = 10-20 mEq/hour IV

38. HYPERKALEMIA Plasma K > 5.0 mEq/L

39. Etiology of Hyperkalemia Movement from cells to ECF Metabolic acidosis Insulin deficiency and hyperosmolarity (DM) Tissue catabolism B adrenergic blockade Severe exercise Digitalis overdose Periodic paralysis – hyperkalemic form

40. Etiology of Hyperkalemia Decrease Urinary Excretion Renal failure Effective circulating volume depletion RTA – hyperkalemic form Hypoaldosteronism

41. Etiology of Hyperkalemia Hypoaldosteronism NSAID Converting enzyme inhibitors Cyclosporine K sparing diuretics Primary adrenal insufficiency

42. Sign and Symptoms Cardiac 5.0 – 6.5 = peak T wave 6.5 – 8.0= flattening of P wave, prolongation of PR interval, widening of QRS complex >8.0 = sine wave pattern, V fibrillation or cardiac arrest

43. Treatment Antagonism of Membrane Calcium gluconate = 10 – 20 ml Peak effect = 5 minutes

44. Treatment Increase K entry into the cells Glucose–Insulin solution ( 10 u in 50 ml D50W) Sodium Bicarbonate B adrenergic agonist

45. Treatment Removal of Excess K Diuretics Cation exchange resin Hemodialysis or Peritoneal Dialysis