INTERACTIVE CASE DISCUSSION

1. INTERACTIVE CASE DISCUSSION Fluid and Electrolyte Disorders Part I

2. Introduction to Fluids and Electrolytes Fluid & Electrolyte Status Assessment • Sodium (Na) balance • Potassium (K) balance • Water balance • Other ions: Ca, Mg, Phosphate, etc.

3. Introduction to Fluids and Electrolytes Fluid & Electrolyte Status Assessment • “Hypo” – deficit • “Hyper” – excess • “Eu” or “Normo” - normal; adequate

4. Introduction to Fluids and Electrolytes Assessment of Potassium (K) Balance • Measuring tool: serum K • K = 3.5 - 5meq/L • Hypokalemia: < 3.5 meq/L • Normokalemia: 3.5 – 5meq/L • Hyperkalemia: > 5meq/L

5. Introduction to Fluids and Electrolytes Assessment of Water Balance • Measuring tool: serum Na • Hypernatremia ( >145 meq/L): water deficit • Normonatremia ( 135-145 meq/L): normal water balance • Hyponatremia ( <135 meq/L): water excess

6. Introduction to Fluids and Electrolytes Assessment of Sodium (Na) Balance • Measuring tool: Physical examination of the patient’s volume status • Hypervolemia: Na excess;  BP, JVP, edema, ascites, effusion etc. • Normovolemia: normal Na balance; normal BP, JVP = 8-12; good skin turgor • Hypovolemia: Na deficit; BP, JVP, dry mucosa, poor skin turgor etc.

7. Introduction to Fluids and Electrolytes REMEMBER ! Serum K = K balance Serum Na  Na balance Serum Na = Water balance Volume status = Na balance

8. Introduction to Fluids and Electrolytes Sample Question: A 50 year old male with chronic renal failure has a serum K of 6 meq/L. What is his K status?

9. Introduction to Fluids and Electrolytes Answer: • Normal serum K = 3.5- 5meq/L • Serum K = 6meq/L ( > 5 meq/L) • Hyperkalemia • K excess

10. Fluids and Electrolytes Part I CASE #1: A 45 year old Japanese tourist collapsed in a shopping mall and was brought to the ER. • 90/60, HR = 110/min • JVP = 4, proximal muscle weakness • Labs: Na = 140, Cl = 110, HCO3 = 16, K = 2.

11. Fluids and Electrolytes Part I Question #1: How will you approach the problem of hypokalemia?

12. HYPOKALEMIA Urinary K excretion <15 mmol/d > 15mmol/d Metabolic acidosis Metabolic alkalosis Lower GI K loss Remote diuretic use Remote vomiting K loss via sweating Singer, 2001

13. HYPOKALEMIA Urine K excretion > 15 mmol/d TTKG > 4 TTKG < 2 Na wasting nephropathy Osmotic diuresis Diuretic Singer, 2001

14. HYPOKALEMIA TTKG > 4 Metabolic alkalosis Metabolic acidosis Hypertension DKA RTA Ampho B No Yes Vomiting Barrter’s syndrome Diuretic abuse Hypomagnesemia Mineralocorticoid excess Liddle’s syndrome Singer, 2001

15. Fluids and Electrolytes Part I Question #2: What test will you order next in order to work-up the cause of the hypokalemia?

16. Fluids and Electrolytes Part I Answer #2: 24-hour urine collection to measure 24-hour urinary K excretion.

17. Fluids and Electrolytes Part I Question #3: The 24-hour urinary K excretion rate is 10 mmol/day. Which of the following is the most likely cause of hypokalemia? • Barrter’s syndrome • Diarrhea • Hypomagnesemia • Liddle’s syndrome

18. Fluids and Electrolytes Part I Answer #3: Diarrhea • The 24-hour urine K excretion is less than 15 mmol/day. • Rest of the choices are renal K-wasting states wherein the 24-hour urine K excretion should be > 15mmol/d. • The patient later admitted thru an interpreter that he ate fishballs from a sidewalk vendor 2 days ago and has been having diarrhea since then.

19. Fluids and Electrolytes Part I Case # 4: 38 y/o male alcoholic with cirrhosis. Admitted bec. of anorexia and cachexia. He is not on any medications. • BP = 90/60, HR = 105/min • ABGs: pH= 7.42, pCO2 = 35, HCO3 = 22 • Creatinine = 0.7 mg/dl (normal) • Urea = 8 mg/dl () • K = 6 meq/L ()

20. Fluids and Electrolytes Part I Question #4:How will you approach the problem of hyperkalemia in this patient?

21. HYPERKALEMIA Exclude pseudohyperkalemia Exclude transcellular K shift Exclude oliguric renal failure Stop NSAIDs and ACE-inhibitors Assess K excretion Singer, 2001

22. HYPERKALEMIA Assess K excretion TTKG > 10 (increased distal flow) TTKG < 5 Low protein diet  Effective circulating volume Response to 9fluodrocortisone Singer, 2001

23. HYPERKALEMIA Response to 9-fluodrocortisone TTKG < 10 TTKG  10 Primary or Secondary hypoaldosteronism BP  renin & aldosterone BP  renin & aldosterone Measure renin & aldosterone Pseudohypoaldosteronism K-sparing diuretics Trimethoprim Pentamidine Gordon’s syndrome Cyclosporine RTA (IV) Singer,2001

24. Fluids and Electrolytes Part I Question #5: What is the next test to order in order to work-up the cause of this patient’s hyperkalemia?

25. Fluids and Electrolytes Part I Answer #5: Compute for the Transtubular K Gradient (TTKG). TTKG = Uk/Pk  Uosm/Posm Uk = Urine K Pk = Plasma K Uosm = Urine osmolality Posm = Plasma osmolality

26. Fluids and Electrolytes Part I TTKG (Transtubular K Gradient): • In hyperkalemia: < 5, diminished aldosterone effect  10, normal aldosterone effect, non-renal hyperkalemia

27. Fluids and Electrolytes Part I Question #6: The urine and plasma values are as follows: Pk = 6 meq/L Uk = 54 meq/L Posm = 280 mmosm/kg Uosm = 260 mmosm/kg Compute for the TTKG.

28. Fluids and Electrolytes Part I Answer #6: TTKG = 10 TTKG = Uk/Pk  Posm/Uosm = 54/6  280/260 = 9/0.9 = 10

29. Fluids and Electrolytes Part I Question #7: What is the most likely cause of the patient’s hyperkalemia? • Hypoaldosteronism • K - sparing diuretics (Spironolactone) • Low protein intake • Renal tubular acidosis (RTA)

30. Fluids and Electrolytes Part I Answer # 7: Low protein intake • TTKG  10 means normal aldosterone effect (not hypoaldosteronism) • In the rest of the choices, the TTKG should be < 5. • Patient is likely to have a low food intake (history of anorexia, low serum urea) due to his alcoholism.