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RenalMain51-60Q1A52-year-oldmanwithalcoholismcomestotheemergencydepartmentduetogeneralizedweakness,anxiety,andtremors.Hislastdrinkwas2daysago.Hehasnosignificantmedicalhistoryandnomedicalfollow-up.ThepatientsmokescigarettesbutdoesnotuseIllicitdrugs.Hetakesnomedications.Onexamination,heappearsdisheveledandmalnourished.Hisinitialelectrolytepanelresultsareasfollows:Heistreatedforalcoholwithdrawalandgivenaggressiveintravenouspotassiumaswellasoralpotassiumsupplementation.Threedayslater,hiselectrolytepanelresultsareasfollows:Whichofthefollowingbestexplainswhythispatient'spotassiumlevelisverydifficulttocorrect?A.AlcoholwithdrawalB.HypoalbuminemiaC.HypomagnesemiaD.HypophosphatemiaE.PoororalabsorptionF,RenaltubularacidosisG.ThiaminedeficiencyA1Correctanswer:CChronicalcoholismisassociatedwithahighincidenceofseveralelectrolyteabnormalities,ofwhichhypomagnesemiaisthemostcommon(likelyduetopoornutritionalintake,alcohol-inducedrenallosses,anddiarrhea).Hypomagnesemiacommonlyoccurstogetherwithhypokalemiaandisawell-knowncauseofrefractoryhypokalemia(hypokalemiathatcannotbecorrectedwithpotassiumreplacement).intracellularmagnesiumisthoughttoinhibitpotassiumsecretionbyrenaloutermedullarypotassium(ROMK)channelsinthecollectingtubulesofthekidney.Therefore,lowintracellularmagnesiumconcentrationsresultinexcessiverenalpotassiumlossandrefractoryhypokalemia.NormalizationofmagnesiumlevelsrestoresROMKchannelpotassiumtransportregulation,decreasesrenalpotassiumlosses,andailowsforsuccessfulcorrectionofhypokalemiawithoral(preferred)orintravenouspotassiumrepiacement.(ChoiceA)AcutealcoholwithdrawalmayinitiallycontributetohypokalemiathroughanincreaseInsympatheticnervoussystemactivity,whichshiftspotassiumintocells.However,itisunlikelytoplayasignificantroleinthispatient'shypokalemia,whichhaspersistedthroughout3daysoftreatment.(ChoiceB)Hypoaibuminemiaiscommonlyseeninpatientswithalcoholismduetopoornutritionorhepaticsyntheticdysfunction,itisacommoncauseoftotalhypocalcemia(duetoahighproportionofserumcalciumbeingprotein-bound)butisnotasignificantcauseofhypokalemia.(ChoiceD)Hypophosphatemiaiscommoninpatientswithalcoholismand,whensevere,canresultinweakness,rhabdomyolysis,paresthesias,andrespiratoryfailure.Itdoesnotdirectlycontributetohypokalemia.(ChoiceE)Poororalabsorptionmayresultinhypokalemiarefractorytooralreplacement,butitisunlikelyinthispatientwithhypokalemiathathasalsobeenrefractorytoaggressiveintravenousreplacement.(ChoiceF)TypeIorIIrenaltubularacidosiscancausehypokalemiabutisusuallyassociatedwithmetabolicacidosis.Thispatienthasarelativelynormalserumbicarbonatelevel,andhishistoryofalcohoiismmakeshypomagnesemiaamorelikelycauseofhisrefractoryhypokalemia.(ChoiceG)ThiaminedeficiencyiscommonInpatientswithalcoholismduetopoornutrition,butItdoesnotcauserefractoryhypokalemia.Educationalobjective:Patientswithchronicalcoholismoftenpresentwithmultipleelectrolyteabnormalities(eg,hypokaiemia,hypomagnesemia,hypophosphatemia).Hypomagnesemiacanleadtorefractoryhypokaiemiaduetoremovalofinhibitionofrenalpotassiumexcretionandshouldbesuspectedinpatientswithhypokalemiathatisdifficulttocorrectwithpotassiumreplacement.Q2A55-year-oldmancomestotheemergencydepartmentduetoprogressivelyworseningshortnessofbreathforthepast3days.Healsoreportswheezingandproductivecoughwithpurulentsputum.Thepatient'smedicalhistoryincludeschronicbronchitisandbenignprostatichyperplasia.Hesmokesapackofcigarettesdaily.Temperatureis37.2℃(99℉);bloodpressureis150/90mmHg,pulseis114/min，andrespirationsare26/min.Thepatient'spulseoximetryshows84%onroomair.Heisalertandansweringquestionscoherently.Examinationshowsdecreasedbreathsoundsanddiffusewheezingoveralllungfields.Thepatientisadmittedtothehospitalandstartedonantibiotics,systemiccorticosteroids,andnebulizedalbuterolandipratropium.Thefollowingday,laboratoryresultsareasfollows:Serumchemistry2daysagowasnormal.Whichofthefollowingisthemostlikelycauseofthispatient'slowserumpotassium?A.DecreaseinavaiiabiiityofinsulinB.DecreaseinextracellularpHC.DecreaseinmineralocorticoidactivityD.Increasedbeta-adrenergicactivityE.IncreasedbloodcellproductionF.IncreasedgastrointestinallossA2Correctanswer:DLowserumpotassiummayresultfromIncreasedpotassiumentryintocells,renalpotassiumwasting,orgastrointestinalfluidloss.Thispatientwithanacuteexacerbationofchronicobstructivepulmonarydisease(CORD)istreatedwithanInhaledbeta-2adrenergicagent(albuterol).Exogenousandendogenous(eg,epinephrine)beta-adrenergicagonistscauseapotassiumshiftintotheintracellularspacebystimulatingthesodium-potassiumATPasepumpandthesodium-potassium-2chloridecotransporter.Adrenergicagentsalsostimulatereleaseofinsulin,whichfurtherpromotesintracellularpotassiumshift,causinghypokalemia.(ChoiceA)insulinpromotespotassiumshiftintotheintracellularspaceandisusedinthemanagementofhyperkalemia.Decreasedinsulinavailabilitywouldexacerbatehyperkalemia.(ChoiceB)DecreasedpH(acidosis)withCOPDexacerbationmaybeseeninpatientswithCO,retention.However,thiswouldresultinhyperkalemia.(ChoiceC)Renalpotassiumwastingwithhypertensionisafeatureofp