CME - Hypokalemia
-
Upload
stanley-medical-college-department-of-medicine -
Category
Health & Medicine
-
view
13.687 -
download
6
Transcript of CME - Hypokalemia
APPROACH TO HYPOKALEMIA
Dr.M.EDWIN FERNANDOAssociate Professor & Head Department of NephrologyChengalpattu Medical College
Goals of this talk . . .
SESSION OBJECTIVES Learn to effectively assess & manage hypokalemia Apply your knowledge to real cases!
LEARNING METHODS Lecture/material review Interactive case scenarios Practical approach to handling hypokalemia in MOST
hospitalized patients
Guideline for supplementing K based on some evidence-based medical recommendations
Big head - Think big
Big ears - listen
patiently
Narrow eyes - Watch deeply
Long nose - Poke around
inquisitively
Small mouth - Speak less &
listen more
POTASSIUM. . .
Most abundant cation in the human body Atomic no.:19 Molecular weight : 39 Maintenance of k balance –
essential for a variety of cellular functions & neuromuscular transmission
Total body stores : 3000 – 4000mEq 98% - located in the cells
POTASSIUM. . .
Intracellular K+ concentration : 140 meq/l Extracellular concentration : 4-5 meq/l Difference is maintained by the Na+-
K+-ATPase Ratio of K+ concentration inside cell &
outside - major determinant of resting membrane potential
Participates – protein & glycogen synthesis
POTASSIUM METABOLISM
K HOMEOSTASIS – KEY HORMONES
Gennari FJ,NEJM,339:451-458:1998
Na & K transport in P cell in CCD
www.uptodate.com
ALDOSTERONE ACTION IN PRINCIPAL CELLS
Hypokalemia Overview
Plasma K < 3.5 mEq/L Occurs in > 20% of hospitalized
patients May be asymptomatic Usually does not require emergency
supplementation over minutes to hours
Can be dangerous - arrhythmias, rhabdomyolysis, paralysis
HYPOKALEMIA
Clinical manifestations determine urgency & magnititude of treatment, not laboratory values
Frequent reassessment of K required
ABG - useful
HYPOKALEMIA – CLINICAL MANIFESTATIONS
CVS : ECG changes,atrial/ventricular arrhythmias,digitoxicity
SKELETAL MUSCLE : Weakness,cramps,tetany,paralysis, rhabdomyolysis
SMOOTH MUSCLE : Constipation,Ileus,urinary retention
ENDOCRINE : Carbohydrate intolerance
HYPOKALEMIA – RENAL EFFECTS
Impaired concentrating ability – polyuria & polydipsia – Nephrogenic DI
Impaired ammonia production – hepatic failure
Impaired urinary acidification Renal insufficiency - RBF,GFR Cl wasting/Metabolic alkalosis Renal cyst formation Tubular vacuolization Interstitial nephritis
PSEUDOHYPOKALEMIA
Abnormal WBCs – in large numbers(AML) – can take up extracellular K when stored at room temp
Apparent hypokalemia – artefact of storage procedure
Rapid separation of plasma/storing at 4 deg C – confirms diagnosis, avoids this artefact & inappropriate Rx Kamel KS,1996
HYPOKALEMIA - CAUSES
DRUGS GI LOSS : Vomiting,NG suction,diarrohea SKIN :Profuse sweating,extensive burns HORMONES : Aldosterone,Steroids, RVH
Malignant HT,Renin secreting tumors,CAH BICARBONATURIA : d
RTA,Rx of p RTA,Rx of met. Alkalosis MAGNESIUM DEFICIENCY INTRINSIC RENAL TRANSPORT DEFECTS :
Bartter´s,Gitelman´s,Liddle´s syndromes
HYPOKALEMIA – DRUG INDUCED
TRANSCELLULAR K SHIFT
RENAL K LOSS
K LOSS IN STOOL
EpinephrinePseudoephedrineSalbutomolTheophyllineRitodrineVerapamilChloroquineInsulin overdose
AcetazolamideThiazidesLoop diureticsFludrocortisonePencillinAminoglycosideAmphotericin BCisplatin
PhenolphthaleinNa polystrene sulfonate
HYPOKALEMIA - ECG ST depressions with prominent U waves &
prolonged repolarization
HYPOKALEMIA - ECG Prominent U wave in V3 & V4 giving the conjoined T- U
wave the appearance of "camel's hump" "apparently" prolonged QT interval in S2 & AVF - due to
the T wave is actually a U wave with a flattened T wave merging into the following U wave – "roller coaster effect "
HYPOKALEMIA - STEPWISE APPROACH
TTKG
TTKG
Transtubular Potassium Gradient
TTKG = Uk x Posm Sk x Uosm
During hypokalemia -TTKG should fall <3 - indicating appropriately reduced urinary excretion of K
TTKG > 4 – indicates renal K loss is due to increased distal K secretion Ethier JH, Am. J. Kidney Dis. 15 (4): 309–15,1990
Approach to Hypokalemia
Step 1: Redistribution or depletion? Redistribution causes
Insulin therapy - DKA Beta 2 agonists - Salbutomol Metabolic alkalosis Beta 2 adrenergic stimulation – AMI cell proliferation – Rx of megaloblastic anemia Barium poisoining
Replacement of potassium in these settings may lead to overshoot & hyperkalemia
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) Refeeding syndrome (NEVER underestimate!) Endocrinopathies (mineralocorticoid excess) Salt wasting nephropathies/RTA’s Magnesium deficiency (NEVER overlook!)
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!!
S.K(mEq/L)
3.5 3 2 <2
TOTALK deficit (mEq/L,70 kg)
125 -250 150-400 300-600 500 -750
HYPOKALEMIA & TOTAL K DEFICIT
Sterns RH, Medicine 60:339-354:1981
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 has less side effects (IV burns!) Oral is less dangerous
Choose IV therapy ONLY in patients who are NPO (for whatever reason) or who have severe depletion
Approach to Hypokalemia Step 4: Choose K+ preparation
Oral therapy Potassium Chloride is PREFERRED AGENT
Especially useful in Cl-responsive metabolic alkalosis
in ECF K quicker with KCl compared to other salts Potassium Phosphate useful when coexistant
phosphorus deficiency Often useful in DKA patients
Potassium bicarbonate, acetate, gluconate, or citrate useful in metabolic acidosis
ORAL POTTASIUM CHLORIDE SOLUTION
15 ML 20 mEq/L
Approach to Hypokalemia
Step 4 (con’t): Choose K+ prep IV therapy
Adjunct to maintenance fluids (10-20 mEq/L) “The surgical intern’s way” Try to avoid using it!!!
you often forget it’s there hyperkalemia can then develop, especially in
patients that get ARF in the hospital IV rider/”piggyback”
Generally 40-60 mEq KCl is PREFERRED AGENT again Avoid dextrose solution (trigger insulin, shift K+)
IV 15%POTTASIUM CHLORIDE 1ml 2 mEq/L 10 ml 20 mEq/L
Approach to Hypokalemia
Step 5: Choose dose/timing Mild/moderate hypokalemia
3.0 to 3.5 mEq/L 60-80 mEq PO (or IV) QDay divided doses Sometimes will require up to 160 mEq per day
(refeeders, lots of diarrhea, IV diuretics) Avoid too much PO at once
GI upset or just poor response Usually divide as BID or TID dosing
Approach to Hypokalemia
Step 5 (con’t): Choose dose/timing Severe hypokalemia (< 3.0 mEq/L)
Can use combination of IV and PO, again with PO preferred if at all possible
Avoid more than 60-80 mEq PO in a single dose
Avoid IV infusion rates faster than 20 mEq/hour—can cause arrhythmia!!!
Most protocols won’t allow more than 10 mEq/hour rates on the floors (ICU’s too?)
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 QDay or less as needed
IV Fluid Iso M Iso P Iso G Iso E RL
K(mEq/L) 35 20 17 10 4
K CONCENTRATION OF IV FLUIDS
Approach to Hypokalemia
Step 7: Housekeeping/follow up BE AGGRESSIVE in DKA patients & IV diuresis
patients May want to keep K+ over 4.0 or even 4.5
mEQ/L in cardiac patients, especially in those with arrhythmias
BE GENTLE in patients with acute or chronic renal failure
May wish to cut doses in half, double intervals, or not replace at all
May need to monitor very closely NEVER forget to check for & treat
hypomagnesemia in refractory hypokalemia!!!
Hypokalemia – TAKE CARE . . .
Monitor IV K – ECG & S.K levels Never give IV push Never add KCl to Iso M
DON’T GIVE MORE THAN10-20mEq/hr40 mEq/L240 mEq/L/day
REMEMBER – THAT HYPOKALEMIA IS SAFER THAN HYPERKALEMIA
AVOID OVERENTHUSIASM in Rx
K RICH FOOD
Fruit juices Tender coconut
water Banana Juicy fruits
Dry fruits Chocolate Coffee Soups Salt substitutes
ACID – BASE DISORDERS IN HYPOKALEMIA
Metabolic acidosis
Metabolic alkalosis
DKA Diuretic therapy
RTA Vomiting, NG
LGI loss( diarrhea, laxative abuse
Mineralocorticoid excess
Salt-wasing nephropathy
Penicillin derivatives
Liddle, Bartter, Gitelman syndromes
HYPOKALEMIA & ABG
HYPOKALEMIA & CONTRACTION ALKALOSIS
UCl IN METABOLIC ALKALOSIS & K
HYPOKALEMIA,HT,METABOLIC ALKALOSIS - DIFFERENTIALS
HYPOKALEMIC METABOLIC ALKALOSIS WITHOUT HT
HYPOKALEMIA & PARALYSIS
Ok, You Think You Got It???
Let’s try it out on some cases Real cases from real patients
Figure out what you would do...
Case 1
30,F Diarrohea,muscle weakness ECG – s/o hypokalemia LABS – Na 140,K 2.1,Cl 117,
bicarb 10,Ph 7.26,Pco2 23 What is your diagnosis? Which would you correct first?
Case1 - discussion
Hypokalemic metabolic acidosis due to diarrohea
Correct hypokalemia first Correction of acidemia pushes K
into cells - further worsening K!
Case 2
36 F Diuretics – twice weekly HT,JVP – 5cm,skin turgor LABS – Na 136,K 3,Cl 98,Bicarb
29,Ph 7.47,UNa 60,UK 45,UCl 48 NS 2L in 1hr,UNa 20 What is your diagnosis &
differentials
Case 2 - discussion
HT,Hypokalemic Metabolic Alkalosis & kaliuresis – PRIMARY HYPERALDOSTERONISM
Diuretic Rx for HT – can mimic Hypovolemia, slight Na,
UNa after NS – BEST EXPLAINS UCl – accurate indicator of volume
depletion in metabolic alkalosis
Case 3
22,F Weakness – persistent O/E – NAD LABS – Na 136,K 2.7,Cl 108,bicarb
17,Ph 7.3,U Na 7,U K 12 What is your diagnosis?
Case 3 discussion
Low UK – extra renal loss Low UNa – volume depletion Metabolic acidosis – diarrohea SUSPECT LAXATIVE ABUSE
Case 4
22,F Easy fatigability & weakness LABS – Na 141,K 2.1,Cl 85,
Bicarb 45,UNa 80,UK 170 What are your differentials ? What further testing you will order ?
Case 4 - discussion
Unexplained K, UK wasting & metabolic alkalosis – diuretic use, vomiting, primary hyperaldosteronism
Urinary Cl – helps further differentials
Case 5
S.K 2.7 Bicarb 27 PH 7.43 UK 10 Uosm 102 – Primary waterloadPRIMARY POLYDIPSIA
Case 6
S.K 2.7 Bicarb 27 Ca 7.3 Alb 4.1 Ph 7.46 UK 45HYPOMAGNESEMIA
Case 7
S.K 2.7 Bicarb 14 Ph 7.28 UK 52 Urine Ph 6 UAG + 25RENAL TUBULAR ACIDOSIS
ODUVANTHALAI leaves - Cleistanthus collinus is an extremely toxic plant poison
Cleistanthin A & B, the toxins of Cleistanthus collinus,are diphyllin glycosides which produce cardiac arrhythmias, urinary potassium wasting, hypoxia, metabolic acidosis & hypotension
We report ARDS, distal renal tubular acidosis and distributive shock secondary to inappropriate vasodilatation in a case following ingestion of its leaves J Assoc Physicians India. 2006 Sep;54:742-4
Cleistanthus Collinus PoisoningSPE Benjamin, M Edwin Fernando, J Jerene Jayanth, B Preetha
Primary Sjögrens Syndrome Presenting with DistalRenal Tubular Acidosis & RhabdomyolysisEBS Prakash, M.Edwin Fernando, Malathi Sathiyasekaran, RM Bhoopathy, JJ Jayanth
Primary Sjögrens syndrome (PSS) is rare in India Clinically manifest renal disease in PSS is
uncommon & is usually an autoimmune tubulointerstitial nephritis presenting with distal renal tubular acidosis (dRTA) or a urinary concentrating defect.
Hypokalemic paralysis due to dRTA in PSS is rare but well documented in medical literature
Rhabdomyolysis as a consequence of hypokalemia in PSS is exceptional
We report a case of PSS with dRTA & rhabdomyolysis causing prolonged respiratory failure and quadriparesis
J Assoc Physicians India. 2006 Dec;54:949 - 50
CASE 10
GITELMAN SYNDROME
HYPOKALEMIA IN LEPTOSPIROSIS
Hypokalemia – 26 to 40% Seguro AC,Nephron 55:146-151,1990
Kaliureis – inhibition of Na reabsorption in PCT with ↑ Na delivery to CD for Na-K exchange Abdulkader RC,Am J Trop Hyg 54:1-6,1996
OMP of leptospires – inhibit Na – K ATP ase – secondary effects on Na transport at luminal sites Younes-Ibrahim M,CR Acad Sci III 318:619-625,1995
Inhibition of Na –K - Cl cotransport in m TAHL Yang CW J Am Soc Nephrol 11;2017-2026,2000
Urinary concentrating ability Respiratory alkalosis - hyperkaliuria Leptospirosis - current scenario in
India,S. Shivakumar Medicine Update 2008
HYPOKALEMIA Recap of Major Learning Points Minimise hypokalemia – adequate intake PO almost always preferred over IV KCl is preferred preparation Don’t give too much too quickly Be aggressive in DKA & IV diuresis
patients,arrhythmia,musular paralysis Be gentle in renal failure patients Don’t forget to check magnesium levels in
refractory hypokalemic patients Remember genetic & endocrine causes galore –
deligent work up essential
Dr.M.A. MuthusethupathiDr.M.JayakumarDr.R.VijayakumarDr.N.Gopalakrishnan
THANKS . . .