146 PART II: PRIMARY CARE DISORDERS
Primary Hyperparathyroidism
General Characteristics
Primaryhyperparathyroidismisadisorderoftheparathy-
roidglands(Figure11–1).Inmostcasesitiscausedbyone
ormoreenlarged,overactiveparathyroidglandssecreting
too much parathyroid hormone (PTH). The parathyroid
glandssecrete PTH,whichmaintains the correctbalance
ofcalciumandphosphorusinthebody.PTHregulatesthe
levelofcalciumintheblood,releaseofcalciumfrombone,
absorption of calcium in the intestine, and excretion of
calciumintheurine.
Whentheparathyroidglandssecretetoomuchhormone,
itcauseshypercalcemiaandmaybetherstsignofhyper-
parathyroidism.In85percentofpeoplewithprimaryhyper-
parathyroidism,abenign(noncancerous)tumorcalledan
adenomahasformedononeoftheparathyroidglands,caus-
ingittobecomeoveractive.Inmostothercases,theexcess
hormone comes from two or more hypertrophied para-
thyroid glands. In very rare cases, hyperparathyroidism
is secondary to cancer of one of the parathyroid glands.
Hyperparathyroidismcanalsomanifestinconjunctionwith
multipleendocrineneoplasia(MEN)typesI,IIA,orIIB,des-
cribed as follows
20,21
:
• MENI:Parathyroidtumors,pancreatictumors,and
pituitarytumors
• MENIIA:Medullarythyroidcancers,pheochromo-
cytoma,andparathyroidtumors
• MEN IIB: Medullary thyroid cancers, pheochromo-
cytoma,andneuromas
Hyperparathyroiddiseaseoccursinabout100,000peo-
pleintheUnitedStatesannually.Womenoutnumbermen
twotoone,andriskincreaseswith age. In women aged
60yearsandolder,twooutof1000will develop hyper-
parathyroidismeachyear.
22
Signs, Symptoms, and Diagnosis
Hyperparathyroidism may present with a wide range of
symptoms,fromseveretosubtleornoneatall.Approxi-
mately50percentofpatientsareasymptomatic.Routine
blood tests that screen for a wide range of conditions,
including high calcium levels, detect patients who have
mildformsofthedisordereventhoughtheyaresymptom
free.Whensymptomsdoappear,theyareoftenmildand
nonspecic,suchasweaknessandfatigue,depression,or
myalgia.Withmoreseveredisease,apersonmayhavea
lossofappetite,nausea,vomiting,constipation,confusion
or impaired thinking and memory, and polydipsia and
polyuria.Asymptomaticosteoporosisincreasestheriskof
fractures.Increasedcalciumandphosphorusexcretionin
theurinemayresultinkidneystones.
23
Diagnosisis madeby demonstrating anelevated serum
PTH(theintactoriPTHisthebestassay)inthepresence
ofanelevatedserumionizedcalciumlevel,lowserumphos-
phorus, and normal or elevated alkaline phosphatase.
Urinalysis may show elevated urine calcium. The elec-
trocardiogram may reveal shortening of the Q-T interval
becauseofhypercalcemia.Whenthediagnosisisestablished,
othertestsshouldbeconsideredtoassessforcomplications.
Abonemineral densitytest measuresosteopenia.A bone
seriesmayshowsubperiostealboneresorption.Theclassic
bonediseaseofprimaryhyperparathyroidismisosteitisb-
rosacystica.Abdominalimagesmayrevealthepresenceof
nephrolithiasis, and a 24-hour urine collection may pro-
videinformationonimpairedkidneyfunction,theriskof
stone formation, and the risk of familial hypocalciuric
hypercalcemia.
21,22
Patientswithhyperparathyroidismshould
undergo further evaluation for the presence of MEN I or
MENII.
Management
Surgery to remove the enlargedgland (or glands) is the
maintreatmentforthedisorderandiscurativein95per-
centofcases.ParathyroidlocalizationwithTc99msesta-
mibi has been shown to have a high sensitivity and
specicityforsingleadenomas.
24,25
Calcimimetics are a new class of drug that turns off
secretionofPTH.TheyhavebeenapprovedbytheFDAfor
thetreatmentofhyperparathyroidismsecondarytokidney
failure with dialysis and primary hyperparathyroidism
causedbyparathyroidcancer.Theyhavenotbeenapproved
forprimaryhyperparathyroidismbutareoccasionallycon-
sideredforoff-labeluseinselectpopulations.
Lifestyle Changes: Practical Tips for Your
Patients
Mild disease may not need immediate treatment,
accordingtotheNationalInstitutesofHealth.Asymp-
tomatic patients whose blood calcium is slightly
elevated, without renal involvement or osteopenia,
mayconsiderlong-term monitoring. Ina2002 rec-
ommendation,periodicmonitoringconsistsofclini-
calevaluation,measurementofserumcalciumlevels,
andbonemassmeasurement.Ifthepatientandphy-
sicianchooselong-termfollow-up,thepatientshould
drinklotsofwater,getplentyofexercise,andavoid
certaindiuretics,suchasthe thiazides.Immobiliza-
tion and gastrointestinal illness with vomiting or
diarrhea can cause calcium levels to rise. Patients
withhyperparathyroidismshouldseekmedicalatten-
tioniftheybecomeimmobilizedorhavevomitingor
diarrhea.
21,22
Primary Hypoparathyroidism
General Characteristics
Hypoparathyroidism is a disorder of the parathyroid
glands(Figure11–1)andinmostcasesiscausedbysur-
geryperformedtocorrectanoveractivegland.Theinci-
denceisratherrarewithanoccurrenceof4outof100,000
people.Insomecases,thediseaseiscausedbyanautoim-
muneprocessthatdestroystheparathyroidglands(orin
rarecasesafterneckradiationforcancer).Therearealso
forms of hypoparathyroid disease caused by congenital
Chapter 11: Endocrine Disorders 147
andfamilialabnormalities.IthasbeendescribedasWilson
diseaseandhemachromatosis.
26,27
TheparathyroidglandssecretePTH,whichmaintains
thecorrectbalanceofcalciumandphosphorusinthebody.
Parathyroidhormoneisnotregulatedbythepituitaryor
hypothalamus.Parathyroidhormoneregulatesthelevelof
calciumintheblood,releaseofcalciumfrombone,absorp-
tionofcalciumintheintestine,andexcretionofcalcium
intheurine.Whentheparathyroidglandsdonotsecrete
enoughPTH,itcauseshypocalcemia(Figure 11–3).
Signs, Symptoms, and Diagnosis
Hypoparathyroidismisassociatedwithaspectrumofclini-
cal manifestations, ranging from few, if any, symptoms
whenthehypocalcemiaismildtolife-threateningseizures,
refractoryheartfailure,orlaryngospasmifitissevere.The
most common symptoms in patients with hypoparathy-
roidismaredentalchanges,cataracts,basalgangliacalci-
cation,andextrapyramidaldisorders,whicharetheresult
ofchronichypocalcemia.Inacutehypocalcemiasymptoms
oftetany,papilledema,andseizuresmayoccur.Thetetany
maybemild(tinglingofthehandsandfeetormildmuscle
cramps)orsevere(laryngospasmandseizures).Lessspe-
cicsymptomsofhyperirritability,anxiety,anddepression
havebeenreported,andsomepatients,evenwithsevere
hypocalcemia,havenoneuromuscularsymptoms.
28
Thediagnosisismadebylaboratorytests.Thetotaland
ionized serum calcium concentrationsare low (false posi-
tives can occur with hypomagnesemia). The serum phos-
phorusconcentrationwillbeelevatedinhypoparathyroidism
(lowinrickets).IntactPTHlevelswillbelow.Additional
tests may include 25-OH-D and 1,25(OH)
2
D
3
vitamin D
levelstodifferentiatehypoparathyroidismfromrickets.
Management
Themanifestedclinicaleffectsofhypoparathyroidismare
usually correctablewith replacement therapy. Few com-
plications,suchas basal ganglioncalcications,areirre-
versible. Most patients with hypoparathyroidism require
lifelongcalciumandvitaminDsupplementation.Anexcep-
tion is the occurrence of transient hypoparathyroidism
after thyroidectomy or parathyroidectomy, which may
occurinupto20percentofsurgicalpatients.
Lifestyle Changes: Practical Tips for Your
Patients
Whentheinactivityofparathyroidhormoneisaresult
ofhypomagnesemia,itiseasilytreatedwithmagnesium
supplementation.At this time,a replacementform of
PTHisnotavailable.
27
Figure 11–3 Hypoparathyroidism ow chart.
Diminished
release of calcium
from bone
Excess reabsorption
of phosphate by
kidneys
Absent or diminished Parathyroid hormone (PTH)
Parathyroid gland removal or injury
Symptoms of hypoparathyroidism
(Seizures, tetany, larygospasm, or neurological abnormalities)
Hyperphosphatemia
Decreased
intestinal calcium
absorption
Reduced
reabsorption of
renal calcium
Hypocalcemia

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