Normal and Abnormal Thyroid Normal and Abnormal Thyroid Function (and How to Interpret Function (and How to Interpret Thyroid Function Tests) Thyroid Function Tests) Dr Ketan Dhatariya Dr Ketan Dhatariya Consultant Endocrinologist NNUH Consultant Endocrinologist NNUH
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NNMAIN KD12 Thyroid Function - Normal and Abnormal.ppt ... · –Goitrogens (including antithyroid drugs or kelp) –Genetic disorders: Dyshormonogenesis, thyroid hormone resistence
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Normal and Abnormal Thyroid Normal and Abnormal Thyroid
Function (and How to Interpret Function (and How to Interpret
–– Drugs: I containing contrast media, Drugs: I containing contrast media, amiodarone, lithiumamiodarone, lithium
–– Congenital: absent or ectopic glands, or Congenital: absent or ectopic glands, or dyshormonogenesis, TSH receptor mutationdyshormonogenesis, TSH receptor mutation
excessive stimulation from excessive stimulation from ββHCG in pregnancy HCG in pregnancy
or choriocarcinomaor choriocarcinoma
Causes of GoitreCauses of Goitre
Thyroid Function TestsThyroid Function Tests
•• About 90% to 95% of all thyroid problems About 90% to 95% of all thyroid problems can be diagnosed using measurements of can be diagnosed using measurements of Thyroid Stimulating Hormone (TSH), Free Thyroid Stimulating Hormone (TSH), Free Thyroxin (fT4), and Free TriThyroxin (fT4), and Free Tri--iodothyronine iodothyronine (fT3)(fT3)
•• Making a diagnosis is all about pattern Making a diagnosis is all about pattern recognition recognition –– but beware the pitfalls!but beware the pitfalls!
Thyroid Function TestsThyroid Function Tests
•• If the TSH, fT4 and fT3 are within the If the TSH, fT4 and fT3 are within the
normal range the likelihood of thyroid normal range the likelihood of thyroid
dysfunction can be excludeddysfunction can be excluded
Low TSH, High fT4, and High fT3Low TSH, High fT4, and High fT3
•• Weight loss, muscle weakness and AF occur Weight loss, muscle weakness and AF occur
commonlycommonly
Type II AITType II AIT
•• Thyroid gland may be a little enlarged and is Thyroid gland may be a little enlarged and is nonnon--tendertender
•• Suppressed TSH, increased total T4 and fT3Suppressed TSH, increased total T4 and fT3
•• Histologically there is widespread disruption and Histologically there is widespread disruption and follicular scarring follicular scarring –– a unique findinga unique finding
•• Poorly Poorly vascualarvascualar
Treatment of AITTreatment of AIT
•• Limited options due to the high iodine load, Limited options due to the high iodine load,
making targeted Imaking targeted I131131 uptake reduced to only 1uptake reduced to only 1--
2% 2% -- not enough to allow it to be used not enough to allow it to be used
therapeuticallytherapeutically
•• However, in type I, the autonomous nodules However, in type I, the autonomous nodules
may allow sufficient uptake to occur to treat may allow sufficient uptake to occur to treat
them with RAIthem with RAI
Treatment of AITTreatment of AIT
•• AntiAnti--thyroid drugs may work less well due to the thyroid drugs may work less well due to the
high iodine loadhigh iodine load
•• Treatment is therefore clinically basedTreatment is therefore clinically based
–– General state of the patientGeneral state of the patient
–– Presence and degree of cardiac decompensationPresence and degree of cardiac decompensation
–– Need for rapid reversal to a euthyroid state Need for rapid reversal to a euthyroid state
Treatment of AITTreatment of AIT
•• ConsiderationsConsiderations
–– Is it safe to stop the amiodarone?Is it safe to stop the amiodarone?
–– If not thenIf not then
•• Antithyroid drugs (better for type I than type II)Antithyroid drugs (better for type I than type II)