Clinical decisions in pediatric nephrology: a problem-solving approach to clinical cases

418 Pages·2008·2.46 MB·english

by  Farahnak Assadi

Clinical Decisions in Pediatric Nephrology
Farahnak Assadi, M.D.
Clinical Decisions
in Pediatric Nephrology
A Problem-solving Approach
to Clinical Cases
FarahnakAssadi,M.D.
ProfessorofPediatrics
Director,SectionofPediatricNephrology
RushUniversityMedicalCenter
Chicago,Illinois
ISBN-13:978-0-387-74601-2 e-ISBN-13:978-0-387-74602-9
LibraryofCongressControlNumber:2007933400
(cid:2)c 2008SpringerScience+BusinessMedia,LLC
Allrightsreserved.Thisworkmaynotbetranslatedorcopiedinwholeorinpartwithoutthewritten
permission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York,
NY 10013, USA),except forbrief excerpts inconnection with reviews orscholarly analysis. Usein
connectionwithanyformofinformationstorageandretrieval,electronicadaptation,computersoftware,
orbysimilarordissimilarmethodologynowknownorhereafterdevelopedisforbidden.
Theuseinthispublicationoftradenames,trademarks,servicemarks,andsimilarterms,eveniftheyare
notidentifiedassuch,isnottobetakenasanexpressionofopinionastowhetherornottheyaresubject
toproprietaryrights.
Printedonacid-freepaper.
9 8 7 6 5 4 3 2 1
springer.com
This bookisdedicated totheindividualswho
havegiven meaningtomylife:
• To the memory of my mother whose hon-
esty and fairness served as a model that I
have tried to emulate. Her continued love
has allowed me to maintaina frameof ref-
erence whichhasassured myhappiness
• To my father who remains, in his later
years, a source of inspirationto three gen-
erationsoflovingprogeny
• To my wife, Nassrin, for her support,
patience, understanding and great sacri-
fices inorder formeto pursuemycareer
• To my children, Ladan and Ramin–and to
my grandchildren, Emily, Mathew, Caro-
line, and Christian–who provide my hope
forthefuture
• To all medical students, residents, and fel-
lows who haveenrichedmylife
• To all the children for whom I have cared,
who always taughtmeso much
Preface
Over the last twenty-five years of teaching, I have found the evidence-based
medicineapproachtobe veryeffectivein teachingclinicalnephrologyto students
ofhealthprofessionsatallstagesoftheirtraining.Forthisreason,Ibelievethatthe
time has come to undertake the task of publishing a comprehensivebook dealing
withcommonrenaldisordersastheypresentinclinicalpractice.
Thisbookisdesignedtoexpandtheclinicalknowledgeandexperienceofresi-
dentsintrainingandthepracticingclinician.Theformatofcasereportswillillumi-
natethebasicprinciplesandpathophysiologyofdiseasesofthekidneyanddefine
diagnosisandtreatment.Theselectedcasereportsfocusontheessentialaspectsof
thepatient’spresentationfindingsandmanagementsneededtoassistinthedifferen-
tialdiagnosis.Theydevelopaprocessoflogicalquestioningfromthepresentation
ofthesignsandsymptomsandlaboratorydata,andtheyarepresentedinthewayin
whichourpatientscometo uswith theirsignsandsymptomsorarereferredtous
byourcolleagues.Eachquestionisfollowedbyadetaileddiscussionthatreviews
recentpublicationsandtranslatesemergingareasofscienceintodatathatisuseful
at the bedside. The content is an evidence-based medicine approach, resulting in
improvedquality,safety,andcost-effectivenessofpatientcare.Anupdatebibliog-
raphy will conclude each set of clinical cases. This format will help readers stay
abreastofdevelopingareasofclinicalnephrology.
IamappreciativeoftheworkofthemedicaleditorsofSpringerPublishers,Inc.,
for their contributions to this endeavor and all those persons who have dedicated
theirskills,intelligence,andworktohelpmakethisabookofoutstandingeditorial
quality.
FarahnakAssadi,M.D.
ProfessorofPediatrics
Director,SectionofNephrology
RushUniversityMedicalCenter
Chicago,Illinois
vii
Acknowledgements
ManyoftheindividualstowhomIammostindebtedareonlyindirectcontributors
tothisbook.Theyarethepeoplewhosawsomeglimmerofhopeintheauthorearly
in his career and nurtured him in what has been the most rewarding life in pedi-
atrics and nephrology.From my student and residency years, Professors Moham-
madGharibandArthurHervadaweregreatteachersandalwayshighlysupportive
when my knowledge had profound limitations. During my fellowship training at
the University of Pennsylvania and Children’s Hospital of Philadelphia, Michael
E.Normanestablishedthegroundworkformysubsequentworkinnephrology.He
providedanintellectualenvironmentandIhavealwaysbeengratefulforhisefforts
onmybehalf.
InthebeginningofmycareerattheUniversityofIllinois,onecouldhardlyhave
hadabettermentorthanProfessorIraRosenthal.AftermovingtoThomasJefferson
University, I received extraordinary help from Michael Norman. He supported
my efforts to establish the core of an outstanding nephrology program at Dupont
Hospital for Children. Leading the Division of Nephrology at Rush University
Medical Center has been one of the greatest fortunes of my life. Samuel Gotoff
andKennethBoyerhavemadeitenjoyabletocometoworkeachandeverydayfor
the pastseveralyears.OurresidentsatRush haveenrichedthe clinicalexperience
immensely.
FarahnakAssadi
ix
Contents
1 FluidandElectrolyteDisorders.................................. 1
2 Acid-baseDisturbances ......................................... 69
3 DisordersofDivalentIonMetabolism ............................ 97
4 Nephrolithiasis.................................................125
5 Hypertension ..................................................145
6 AcuteRenalFailure ............................................167
7 HereditaryNephritisandGeneticDisorders.......................201
8 Glomerular,Vascular,andTubulo-InterstitialDiseases .............237
9 ChronicKidneyDisease.........................................287
10 RenalOsteodystrophy ..........................................313
11 End-StageRenalDiseaseandDialysis ............................337
12 Transplantation................................................353
Index .............................................................377
xi
Chapter1
Fluid and Electrolyte Disorders
CASE 1
A16-yearoldfemaleisbroughtintothehospitalinastuporousstate.Nohistoryis
initiallyobtainable.Thephysicalexaminationisunremarkableexceptfortheabnor-
malmentalstatus.Therearenoobvioussignsofvolumedepletionorexpansion.The
BP is 100/59mmHg. Laboratory data reveal serum sodium 102mEq/l, potassium
2.5mEq/l, chloride 66mEq/l, bicarbonate 32mEq/l, BUN 9mg/dl, and creatinine
0.4mg/dl.Urinesodiumis130mEq/l,potassium61mEq/l,chloride107mEq/land
osmolality467mOsml/kg.
Whatisthemostlikelydiagnosis?
A. Primaryhyperaldosteronism
B. Diureticabuse
C. Bartter’ssyndrome
D. SIADH
E. Excessiveemesis
ThecorrectanswerisB.Thedifferentialdiagnosesofhyponatremia,hypokalemia,
and metabolic alkalosis with a high urine sodium and chloride concentrations is
highly suggestive of diuretic abuse. Hypokalemia essentially excludes SIADH.
Neither hyperaldosteronismnor Bartter’s syndrome causes marked hyponatremia.
Thehighurinechlorideexcludesvomiting,suggestingthepatienthassurreptitious
diuretic abuse. The urine sodium pluspotassium is well abovethatin the plasma;
thus, solute is being lost in excess of water, which will directly lower the plasma
sodiumconcentration.
References
ChungHM,KlugeR,SchrierRW,AndersonRJ(1987)Clinicalassessmentofextracellularfluid
volumeinhyponatremia83:905–908
AssadiF(1993)Hyponatremia.PediatrNephrol7:503–505
FichmanMP,VorherrH,KleemanCR,etal.(1971)Diuretic-inducedhyponatremia.AnnIntern
Med75:853–563
F.Assadi,ClinicalDecisionsinPediatricNephrology. 1
(cid:2)C Springer2008
2 ClinicalDecisionsinPediatricNephrology
CanyouestimatetheurinepHinthispatient?
A. AcidpH
B. AlkalinepH
ThecorrectanswerisB.TheurinepHshouldbealkaline;theaniongapintheurine
is positively charged[(Na+ + K+) > Cl−]. This is probablydue to bicarbonate
excretioninanattempttocorrectthemetabolicalkalosis.
Reference
Rose BD, Post TW (2001) Clinical pathology of acid-base and electrolyte disorders, 5th ed,
McGraw-Hill,NewYork,pp699–710
Whatwouldyourinitialtherapybe?
A. Administrationofhypertonicsalinealone
B. Combinationtherapywithhypertonicsalineandpotassiumchloride
C. Administrationofpotassiumchloridealone
D. Combinationtherapy with hpertonicsaline, potassium chloride and potassium
sparingdiuretic
The correct answer is C. Potassium chloride alone will correct the hypokalemia
andmetabolicalkalosisandraisetheplasmasodiumconcentrationtowardnormal;
as potassium enters cells, sodium will leave to maintain electroneutrality,thereby
correcting the hyponatremia. The administration of large amounts of potassium
(4mEq/kg) over the first 24 hours) can raise the plasma sodium concentration by
10mEq/loverthefirstday,whichisthemaximumdesiredrateofcorrectionofthe
hyponatremaia.Ifthiswere ignoredandhypertonicsaline also given,overlyrapid
correctionwouldensue.
References
BerlT,LinasSL,AisenbreyGA,AndersonRJ(1977)Onthemechanismofpolyuriainpotassium
depletion:Theroleofpolydipsia.JClinInvest60:620–625
Robertson GL, Shelton RL, Athar S (1976) The osmoregulation of vasopressin. Kidney Int
10:25–37
CASE 2
A 10-year old female presents with 5 days of severe vomiting. She has no prior
history of gastrointestinal or renal disease. Physical examination reveals a mild
decreaseinskinturgorandanorthostaticfallinBPof7mmHg.
Laboratory studies show sodium 136mEq/l, potassium 3.0mEq/l, chloride
89mEq/l, bicarbonate 35mEq/l, BUN 30mg/dl, creatinine 1.2mg/dl, and arterial