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Electrolyte imbalance

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Presentation on theme: "Electrolyte imbalance"— Presentation transcript:

1 Electrolyte imbalance
Dr. Mohammed Al-Ghonaim MBBS,FRCP(C)

2 Goals of this Tutorial SESSION OBJECTIVES LEARNING METHODS
Learn to effectively assess and manage various electrolyte abnormalities (NA, K) Apply your knowledge to real cases! LEARNING METHODS Lecture/material review Interactive case scenarios

3 Body’s fluid compartments

4 Sodium disorders: body’s fluid compartments
TBW = WEIGHT x .5 (women) or .6 (men) TBW x 1/3 = ECF TBW x 2/3 = ICF ECF x 2/3 = Interstitial compartment ECF x 1/4 = Intravascular compartment What regulate Sodium balance?

5 Water content of the blood HIGH Water content of the blood LOW
Too much water drunk Too much salt or sweating Brain produces More ADH Brain produces Less ADH Water content of the blood normal Low volume of water reabsorbed by kidney High volume of water reabsorbed by kidney Urine output HIGH Urine output LOW (small volume of Concentrated urine) (large volume of dilute urine)

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7 Sodium disorders [Na] is a measure of Na relative to water.
It tells you NOTHING about the total body sodium. Abnormalities in the Na concentration tell us that there are abnormalities in the amount of WATER in the ECF compartment.

8 Hyponateremia Plasma [Na+ <135 Approach: Calculate serum Osmolality
Osmolality = Osmoles/kg of water 2(Na+) + Glucose + BUN Normal is Determine volume status

9 Case Study: (1) 23 yr old male develops watery diarrhea. He comes to your ER lightheaded and orthostatic. On exam: dry MM and tachycardia. Neuro exam is normal and he is alert. - Labs: Na 129, K 3, HCO3 20, BUN 4, Cr 88, Glucose 75, Urine Na 5, Urine osm 520.

10 Hyponatremia Hypotonic Hyponatremia Serum OSM Low Normal High
Marked hyperlipidemia (lipemia, TG >35mM) Hyperproteinemia (Multiple myeloma) Hyperglycemia Mannitol Hypotonic Hyponatremia *Note: all have ↑ADH SIADH: inappropriate Rest: appropriate ECFv * Low High Normal CHF Cirrhosis Nephrosis Hypothyroidism AI SIADH Reset Osmostat Water Intoxication 1° Polydipsia TURP post-op Renal loss (UNa > 20) Diuretics Thiazide K-sparing ACE-I, ARB IV RTA, Hypoaldo Cerebral salt wasting Extra-renal loss (UNa <10) Bleeding Burns GI (N/V, diarrhea) Pancreatitis

11 Hyponateremia Hyponatremia with high osmolality: [Na] is low since water will flow into the ECF compartment as a result of hyperglycemia for example. The calculated and measured osm will be elevated in that case. Na will decrease by approx 1.6 meq/dL for every 100 mg/dl increase in glucose above 100. In the case of mannitol the measured osm will be high but the calculated osm will be low.

12 Case Study: (1) continue
Diagnosis: First step: calculate osmolality Low ( ) Second step: Volume status Low ECF volume Treatment: Acute vs Chronic Any neurological symptoms

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14 Case study-2 72 yr old woman with DM presents to ER with polyuria and polydipsia x 5 days. Normal physical examination. Labs: Na 129, K 4.2, Cl 89, HCO2 3.4, BUN 5, Cr 88, Glucose 780. What is the osm? Why is he hyponatremic? What is the corrected Na? What is the treatment

15 Case study-3 A 50 yr old male with h/o hyperlipidemia has the following labs: Na 125, M-Osm 270, TGs 1000, total protein 85.

16 Case study-4 72 yr old male who is a heavy smoker presents with cough and hemoptysis. His physical exam is completely normal in terms of volume status. CXR reveals a 6 cm left sided chest mass. Labs: Na 125, K 4.2, Cr 1.1, M OSM 270, Urine Na is 45. He takes no meds. TSH and am cortisol are normal. What is causing the hyponatremia

17 Case Study: (5) A 72-year-old woman presents with a 2-day history of presyncope when rising from a chair. Over the last week she has had a bout of viral gastroenteritis with diarrhea. She is drinking 2–3 L of water per day Medications: Hydrochlorothiazide, 25 mg/d, for HTN On examination: She had postural hypotension, JVP is low Labs: sodium 128 mmol/L, potassium 3.1 mmol/L, creatinine 125 mmol/L and urea nitrogen 10 mmol/L.

18 Hypernateremia Plasma [Na] >145
Caused primarily by Na+ gain, or water deficit Etiology: Impaired thirst Water loss Renal Extra renal Na+ gain Trans cellular shift

19 Hypernateremia

20 Case study: (1) 76 yrs old male HTN,DM II, dementia
Admitted to ICU with septic shock, intubated Called to see due to Na154, Bp 125/76mmHg, Urine out put 1.3 L/day

21 Case study: (2) 25 yrs old male presented with polyuria
Found to have Na 156 Bp 110/67 mmHg, low JVP Urine out put=6 L/day Urine osmolality 100 Calculate the osmolar excretion rate 6 x 100 = 600 Mosmole Replace the fluid deficit Dx Diabetes insipidis (central Vs nephrogenic)

22 Potassium disorders Potassium is one of the body's major ions.
98% of the body's potassium is intracellular Total body potassium stores 50 mEq/kg (ie, approximately 3500 mEq in a 70-kg person). potassium homeostasis: GI absorption is complete daily intake of 1 mEq/kg/d ( mEq) 90% of this excess is excreted through the kidneys 10% is excreted through the gut Normal K level: – 5.0

23 Hypokalemia K < 3.5 mEq/L Clinical manifestations: Fatigue Cramps
Constipation Weakness / Paralysis Parasthesias Arrhythmias

24 EKG Changes in Hypokalemia
Flattened T waves ST depressions Prominent U waves Prolonged QT Prolonged PR interval

25 Pathophysiology of hypokalemia
Deficient intake (Poor potassium intake) Due to a shift from extracellular to intracellular Increased excretion Renal Extra renal

26 Case study: (1) 35 yrs old male HTN on treatment
Found to have hypokalemia (K=2.9) referred for evaluation. HCO3=29 Urine K (spot)= 30

27 How to asses kidney response?
Urinary excertion of K U k < 15 mmol/l in hypokalemia U k > 200 mmol/l in hyperkalemia TTKG < 2 in hypokalemia >8 in hyperkalemia

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29 Approach to Hypokalemia
Step 1: Redistribution or depletion? Redistribution causes Insulin therapy (usually in DKA) Beta 2 agonists (e.g. albuterol) Metabolic alkalosis Replacement of potassium in these settings may lead to overshoot and hyperkalemia

30 Approach to Hypokalemia
Step 1: Redistribution or depletion? Depletion causes (common) GI tract losses (diarrhea, vomiting) Loop/thiazide diuretic therapy Other medications (e.g. amphotericin B) Osmotic diuresis (DKA) Endocrinopathies (mineralocorticoid excess) Salt wasting nephropathies/RTA’s Magnesium deficiency

31 Approach to Hypokalemia
Step 2: Estimate the deficit For every 100 mEq below normal, serum K+ usually drops by 0.3 mEq/L Highly variable from patient to patient, however!! For every 10 mEq below normal, serum K+ usually drops by 0.1 mEq

32 Approach to Hypokalemia
Step 3: Choose route to replace K+ In nearly all situations, ORAL replacement is PREFERRED over IV replacement Oral is quicker Oral is less dangerous Increase dietary intake Potatoes / Bananas Choose IV therapy ONLY in patients who are NPO (for whatever reason) or who have severe depletion

33 Approach to Hypokalemia
Step 5: Choose dose/timing Mild/moderate hypokalemia 3.0 to 3.5 mEq/L 60-80 mEq PO (or IV) QD, divided doses Sometimes will require up to 160 mEq QD (severe diarrhea, IV diuretics) Avoid too much PO at once GI upset or just poor response Usually divide as BID or TID dosing Severe hypokalemia (< 3.0 mEq/L) Can use combination of IV and PO Avoid more than mEq PO in a single dose Avoid IV infusion rates faster than 20 mEq/hour—can cause arrhythmia!!!

34 Approach to Hypokalemia
Step 6: Monitor/reassess Severe hypokalemia, DKA patients Reassess labs Q4-6 hours Moderate hypokalemia, IV diuresis patients Reassess labs BID to TID as needed Mild hypokalemia Reassess labs QD or less as needed

35 Summary: Hypokalemia PO almost always preferred over IV
KCl is preferred preparation Don’t give too much too quickly Be gentle in renal failure patients Don’t forget to check magnesium levels in refractory patients

36 Hyperkalemia Symptoms Usually asymptomatic Muscle weakness / paralysis
EKG abnormalities Peaked T waves ST depression 1st degree AVB QRS widening “Sine wave sign”

37 Hyperkalemia Elevated potassium level should be evaluated as to the following: Step 1: Is it real? Step 2: If real, why did it happen? Step 3: Is this an emergency? Step 4: Emergency Rx

38 Pathophysiology of Hyperkalemia
Increase dietary intake shift of K from ICF to ECF such as: acidosis beta blocker insulin deficiency periodic paralysis Decrease renal excretion :

39 EKG changes in Hyperkalemia

40 Approach to Hyperkalemia
Step 1: Is it real? Assess for/exclude pseudohyperkalemia Hemolysis—ask the nurse/phlebotomist/lab tech If suspected—order STAT repeat K+ level Potassium infusion—ask the nurse If suspected—order STAT repeat K+ level from peripheral vein AWAY from infusion site Check CBC (WBC > 70,000, PLT > 1,000) K+ moves out of WBC’s, PLT’s after clotting If suspected—order STAT serum/plasma K+ levels if serum K+ > plasma K+ by more than 0.3mEq/L, suspect pseudohyperkalemia In any case, have low threshold to repeat labs

41 Approach to Hyperkalemia
Step 2: If real, why did it happen? Acute or chronic renal failure Medications (K+ sparing diuretics, ACE inhibitors, ARB’s, BB’s, digoxin, etc.) Endocrinopathies K+ supplements or salt substitutes K+ in IV infusions/TPN

42 Approach to Hyperkalemia
Step 3: Is this an emergency? How high is the potassium level? If serum K+ > or = 6.0 mEq/L, then treat as emergency Are there any EKG changes consistent with hyperkalemia-induced cardiac instability? If yes, then treat as emergency Remember, the lack of EKG changes is NOT always entirely reassuring

43 Approach to Hyperkalemia
Step 3 (con’t): EKG assessment Four stages of EKG changes Peaked T waves PR prolongation QRS widening Sine waves PEA or asystole

44 Approach to Hyperkalemia
Step 4: Emergency Rx Part A: oppose toxic effects on cell membrane IV calcium infusion (gluconate preferred over chloride) Less toxic effects if IV extravasation Give 1-2, 10mL ampules of 10% Calcium gluconate over 2-5 minutes Keep EKG machine attached to patient!!! EKG changes will diminish in 1-3 minutes 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.

45 Approach to Hyperkalemia
Step 4 (con’t): Emergency Rx Part B: Shift K+ into cells Will buy you 1-4 hours before direct elimination methods “kick-in” Insulin/dextrose therapy Give 10U regular insulin IV push, together with 1 ampule (50mL) D50 IV push 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. Adjuncts Beta agonist: Albuterol nebulizer Peak effect in 90 minutes Sodium bicarbonate 1 ampule IV push Onset: 30 minutes Duration: minutes

46 Approach to Hyperkalemia
Step 5: Emergency or non-emergency therapy (usually takes 4-6 hours to work) Direct elimination of K+ from body Sodium polystyrene sufonate (K+ binding resin) plus sorbitol Give Kayexalate gm PO if patient can tolerate PR (retention enema) if upper GI problems Patient needs to have a colon for this to work! Hemodialysis as last resort or in severe cases

47 Summary: Hyperkalemia
Make sure it’s real Determine emergent or not Degree of hyperkalemia, EKG Treat emergent cases with calcium gluconate, insulin, dextrose, and kayexalate +/- dialysis Monitor closely for response to treatment—watch for rebound Fix the cause if possible


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