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Soonchunhyang Medical Science 18(2):122-124, December 2012
pISSN: 2233-4289 I eISSN: 2233-4297
CASE REPORT
A Case of Isolated Thyroid Stimilating Hormone Deficiency
Hyun Wook Cho, Yeo Joo Kim, Sang Jin Kim
Division of Endocrinology, Soonchunhyang University Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan, Korea
Isolated thyroid stimulating hormone (TSH) deficiency is very rare. Only a few patients are reported in the world. A 50-year-old wo­
man was admitted to Soonchunhyang University Cheonan Hospital because of a distal radius fracture. She was diagnosed with hypothyroidism incidentally. Serum free T4 and TSH were low. After administration of exogenous TSH releasing hormone, no TSH response was noted. The response of prolactin and other pituitary hormones were appropriate after stimulation. Pituitary magnetic
resonance image did not reveal any abnormalities. The diagnosis of isolated TSH deficiency was established for this patient.
Keywords: Hypothyroidism; Thyrotropin; Deficiency
INTRODUCTION
edwithisolatedTSHdeficiencywithareviewofthemedicalliterature.
Hypothyroidismisacommondisease.Theprevalenceofhypothyroidismin2009forKoreaincluded248,387people.Hypothy-
CASE REPORT
roidismcanbeclassifiedasprimaryhypothyroidism,transient
causeandcentralone.Secondaryhypothyroidismreferstoahy-
A50-year-oldwomanwithahistoryofhypothyroidismfor6
pothyroidstateassociatedwiththyroidstimulatinghormone(TSH)
monthspresentedtoSoonchunhyangUniversityCheonanHospi-
deficiency.WiththeavailabilityofTSHreleasinghormone(TRH)
talforpainintherightwrist.Radiologicimagingconfirmedadis-
assay,itisnowpossibletoseparatepituitaryoriginfromhypotha-
talradiusfracturebyslipdown.Shewasdiagnosedwithhypothy-
lamichypothyroidism.
roidismduringaroutinehealthscreenatanotherfacility6months
Hypothyroidismismostlycausedbyprimaryhypothyroidism.
priortopresentation.However,despitebeingrecommendedto
Hashimoto’sthyroiditisisthemostcommoncauseofprimaryhy-
takethyroidhormone,shedidnottakeanyofthemedication.She
pothyroidism.Secondaryhypothyroidismisnotcommonandis
hadnopasthistoryofcardiacorrenaldisease,andtherewasno
usuallydiagnosedinthecontextofotheranteriorpituitaryhor-
historyofsignificantalcoholintake,smokingorprevioussurgery.
monedeficiencies,ifitsoriginisfromthepituitarygland.Pitu-
Herfamilyhistorywasalsounremarkable.Uponhistorytaking
itarydiseaseswithmultipleanteriorpituitaryhormonedeficien-
andphysicalexam,shedidnotexhibitanymanifestationforhy-
ciesusuallyoccurinapredictablesequence,withgrowthhormone
pothyroidism.
(GH)andgonadotropindeficiencyprecedingthatofTSHandadrenocorticotropin.
Onadmissionherbloodpressurewas120/80mmHgwitha
pulserateof80beats/min.Physicalexaminationwasunremark-
However,isolatedTSHdeficiencyisveryrareworldwide.Itwas
ableanddisplayednospecificabnormalitiesbesidesherradius
firstreportedin1953byShuman[1].Sincethenonlyafewsporad-
fracture.Laboratorydatashowednoabnormalfindingsexceptin
iccaseshavebeenreported,andtherehavebeenonlytworeported
herthyroidfunctions:serumwhitebloodcellcountwas4,350/μL;
casesinKorea[2].WepresentthecaseofaKoreanfemalediagnos-
hemoglobin12.8g/dL;bloodureanitrogen17.9mg/dL;creatinine
Correspondence to: Yeo Joo Kim
Division of Endocrinology, Soonchunhyang University Cheonan Hospital, Soonchunhyang University College of Medicine, 31 Suncheonhyang 6-gil, Dongnam-gu, Cheonan 330-930, Korea
Tel: +82-41-570-3685, Fax: +82-41-574-5762, E-mail: [email protected]
Received: Jun. 22, 2012 / Accepted after revision: Oct. 9, 2012
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© 2012 Soonchunhyang Medical Research Institute
This is an Open Access article distributed under the terms of the
Creative Commons Attribution Non-Commercial License
(http://creativecommons.org/licenses/by-nc/3.0/).
Secondary Hypothyroidism, TSH Deficiency • Cho HW et al.
Table 1. Results of combined pituitary secretion test
Reference value
0 min
15 min
30 min
60 min
90 min
120 min
Glucose (mg/dL)
GH (mIU/L)
FSH (mIU/mL)
LH (mIU/mL)
TSH (µIU/mL)
ACTH (pg/dL)
Cortisol (µg/dL)
Prolactin (ng/mL)
70-130
90
53
67
31
64
114
0.06-5.0
8.34
4.41
16.47
49.5
52.2
29
25-134
38.05
44.06
49.88
56.59
52.24
53.28
7.7-58
21.09
38.76
51.78
60.06
51.49
47.75
0.27-4.2
0.532
1.76
2.29
1.76
1.16
0.951
5-60
24
36
178
366
266
93
6.1-19
3.64
7.75
11.17
26.07
27.98
26.06
4.6-21
7.26
69.87
76.04
106.5
58.15
33.18
ACTH, adrenocorticotropic hormone; FSH, follicle stimulating hormone; GH, growth hormone; LH, luteinizing hormone.
ranges:TSH0.046µIU/mL;freeT40.946ng/dL;T31.13ng/mL.
DISCUSSION
Mostcommoncausesofprimaryhypothyroidismareprimary,
arisingfromautoimmunethyroiditisandvariousotheriatrogenic
causes.Centralhypothyroidism,whichisfromeitherapituitary
orahypothalamicorigin,isclassifiedassecondaryhypothyroidism,whichisnotamajorcauseofhypothyroidism.
PituitaryhypothyroidismischaracterizedbylowbasalTSH
A
B
Fig. 1. (A, B) Pituitary magnetic resonance imaging did not show any abnormalities in Sella turcica.
levelsinthesettingoflowfreethyroidhormone.Patientswithhypothyroidismofhypothalamicorigin,ontheotherhand,mayexhibitnormalorevenslightlyelevatedTSHlevels.TheTSHproducedinthelattercircumstanceappearstohavereducedbiologic
0.7mg/dL;serumsodiumlevel145mEq/L;serumpotassiumlevel
activityduetoalteredglycosylation[3].HyposecretionofTSHin
4.1mEq/L;aspartateaminotransferase33IU/L;alanineamino-
pituitaryhypothyroidismisascribedtoareducedmassoffunc-
transferase23IU/L;serumglucose103mg/dL.Herthyroidfunc-
tioningthyrotrophsasaconsequenceofvariouslesionsthatcan
tiontestshowedhypothyroidismbasedonlowTSH(0.066µIU/
includemechanicalcompressionbytumor,destructionbyvascu-
mL;normalrange,0.27to4.2);lowfreeT4(0.799ng/dL;normal
lar,inflammatoryorphysicalinjuries,alpasia,orhypoplasia.In
range,0.93to1.7),andnormalT3(1.03ng/mL;normalrange,0.8
addition,itmayalsobeidiopathic,whenthereisnoevidenceof
to2.0).Antibodytothyroglobulinwas520IU/mL(normalrange,
injurytothepituitaryorpresenceofanyneoplasticlesioninthe
0to115IU/mL)andtheanti-thyroidperoxidaseantibodywas600
brain.IdiopathicTSHdeficiencytakesplaceswithcorrelationto
IU/mL(normalrange,0to34IU/mL).Thyroidultrasonography
GHdeficiency[4],butsecretionofotherpituitaryhormonesmay
showednoabnormailities.Theseresultsindicatedherhypothy-
alsobeimpaired[5].Althoughmorecommoninadults,isolated
roidismtobeofsecondaryorigin.Theresultsofcombinedanteri-
TSHdeficiencyalsooccursinchildrenandmayresultinasecond-
orpituitarysecretiontestareshowninTable1.Afteradministra-
aryimpairmentofGHsecretion,includingprimarydeficiencyof
tionofexogenousTRH,noTSHresponsewaselicited.However,
TSHandGH[6].
herprolactinandotherpituitaryhormoneresponsesafterstimu-
IsolatedTSHdeficiencycanoccurbutisveryrare.Severalex-
lationwerenormal.ChestX-raywaswithinnormallimitsandher
planationsforidiopathicisolatedTSHdeficiencyarepossible.Pro-
electrocardiogramshowedanormalsinusrhythm.Pituitarymag-
videdthatthethyrotrophsarepresentandmorphologicallyintact,
neticresonanceimaging(MRI)didnotshowanyabnormalities
theabnormalitycouldresideintheTRHreceptororatsomesub-
(Fig.1).Thepatientwastreatedwithlevothyroxine50μgperday.
sequentstepinthetransmissionofthehypothalamicmessage,in
After2monthsoftreatment,thyroidfunctionreturnedtonormal
theprocessofTSHsynthesis,orTSHrelease.Anyabnormalitiesin
Soonchunhyang Medical Science 18(2):122-124
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Cho HW, et al. • Secondary Hypothyroidism, TSH Deficiency
theTRHreceptordonotinvolveprolactin-secretingcellsbecause
roidism.However,ifthepatienthasanisolatedTSHdeficiency,it
theprolactinresponsetoTRHisnormalinthesepatients[7].
mustnotbeoverlookedthatthelesionresponsibleforthedisease
InheritedisolatedTSHdeficiencyisanautosomalrecessivedis-
mayleadtootherhormonaldeficiencieslateron.Thus,whenapa-
easethatresultsincongenitalhypothyroidismandhasbeenre-
tienthasbeendiagnosedwithisolatedTSHdeficiency,thephysi-
portedafewtimes.Itisrelatedtoeitherasingle-basesubstitution
cianshouldbealertforanysubsequentchangesthatmayrequire
ortoanonsensemutationintheTSH-subunitgene,anddefectsin
additionalevaluationofotherhormonelevelsandtherespective
pituitaryspecifictranscriptionfactorhavebeenalsodescribed[8].
therapyforeachhormoneabnormalitiesasindicated[6].Were-
ThediagnosticcriteriaforisolatedTSHdeficiencyinclude1)a
portthiscasetomakenoteofthefactthatboththediagnosisand
lowlevelofthyroidhormoneswithlowTSHlevelintheserum,
follow-upcareofisolatedTSHdeficiencymustbemeticulously
withnormalorhighserumTRHlevels,2)theabsentresponseof
done.
serumTSHtoexogenousTRHadministration,butwithanormal
serumprolactinlevel,and3)normalsecretionsofotheranterior
pituitaryhormones.ThelaboratorydataacquiredfromourpatientsiscompatiblewithisolatedTSHdeficiency.Thecauseofher
isolatedTSHdeficiencywasnotfoundinherpituitaryMRI.Ageneticanalysiswasnotconductedduetoherrefusal.
Themainclinicalsymptomsofhypothyroidismarefatigue,
weakness,dryskin,feelingcold,hairloss,constipation,dyspnea,
hoarseness,andparesthesia.Thetypicalclinicalfeaturesincludea
puffyfacewithedematouseyelids.However,adultpatientswith
isolatedTSHdeficiencyaregenerallypresentedwithabsentormild
symptomsofhypothyroidism[9].Inoutpatient’scase,shewasdiagnosedincidentallywithhypothyroidismalthoughnosymptoms
oftheconditionwereshown.
TreatmentofTSHdeficiencyisadailyreplacementwithlevothyroxine.Itshouldbeinitiatedafteradequateadrenalfunction
hasbeenestablished.DoseadjustmentisbasedonthyroidhormonelevelsandclinicalparametersratherthantheTSHlevel[10].
Sincethetypicalsymptomswithhypothyroidismareusually
lacking,itisclinicallyimportanttomakethediagnosisofisolated
TSHdeficiency.Administeringthyroidhormone,oncethediag-
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