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 = meq/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 ( 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 = meq/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 TTKG < 5
(increased distal flow)
TTKG < 5
Response to
9fluodrocortisone
Low protein diet
 Effective circulating volume
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.