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Flashcards in Thyroid Deck (95)
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1

What test best assesses thyroid function

TSH

2

What will happen to TSH in primary/secondary hyperthyroidism and primary/secondary hypothyroidism

Primary hyperT->TSH low, negative feedB
Secondary hyperT->+TSH= +T3/T4
Primary hyperT: +TSH->less negative feedB
Secondary hypoT: TSH low/normal with variabl response to TRH depending on site of lesion

3

When should free T3 be measured and why

If TSH suppressed and free T4 normal to rule out T3 toxicosis

4

When are thyroglobulin antibodies, TPO antibodies and TSH receptor inhibiting antibodies found

Hashimotos

5

When are Thyroid stimulating antibodies positive

Grave's

6

What is the role of plasma thyroglobulin monitoring

Used to monitor residual thyroid activity post thyroidectomy
Normal/elevated suggest persistent, recurrent or metastatic disease

7

When might calcitonin be measured

If suspect medullar carcinoma / Men 2a or 2b symptoms

8

What is the role of thyroid USS

Size
Cystic vs solid nodule
FNAB

9

When is technitium scan done

Test of structure-> if nodule and hyperthyroid with low TSH
Differentiates between hot and cold nodules

10

When is radioactive iodine used

Test of function->order if thyrotoxic
Turnover of iodine
+uptake= overactive
-ve uptake->gland is leaking, exogenous hormone use, excess iodine (amiodarone/contrast dye)

11

When is FNA done

Differentiates between benign and malignant

12

When is RAIU increased

Graves
TMG
Toxic adenoma

13

When is RAIU decreased

Subacute thyroiditis
Recent iodine load
Exogenous iodine hormone

14

Define thyrotoxicosis

Clinical, physiological and biochemical findings in response to elevate thyroid hormone

15

Etiology of thyrotoxicosis

Hyperthyroidism:
Graves
MNG
Toxic adenoma

Thyroiditis:
Subacute
Silent
Postpartum

Extrathyroidal:
Endogenous->struma ovarii, teratoma, metastatic follicular
Exogenous

Excessive thyroid stimulation:
Pituitary thyrotroph
Pituitary thyroid hormone receptor resistance
+hCG (pregnancy, -ve TSH, +T4)

Drugs:
Amiodarone
Lithium
Phenytoin
Carbamazepine
Rifampin

16

Clinical features of thyrotoxicosis

General: fatigue, heat intolerance, irritability, fine tremor
CVS: Tachy, AF, palpitations
GI: weight loss, diarrhea, +appetite, thirst, +frequency
Neurology: proximal myopathy, hypokalemic periodic paralysis
GU: oligomenorrhea, amenorrhea, decreased fertility
Dermatology: fine hair, moist, vitiligo, soft nails with onycholysis, palmar erythema. Acropachy and pretibial myxedema in Grave's
MSK: decreased bone mass, muscle weak
Hematology: Graves->leukopenia, lymphocytosis, splenomegaly, lymphadenopathy
Eye: Graves->lid lar, retraction, proptosis, diplopia, decreased acuity, puffy, conjunctival injection

17

Overview management for thyrotoxicosis

Propylthiouracil/Carbimazole
Propranolol
Radioiodine
Thyroidectomy
Get help in pregnancy and infancy

18

Triad of Grave's

Hyperthyroidism
Infiltrative opthalmopathy
Pretibial myxedema

19

Pathogenesis of Graves->pituitary, heart, liver, bone, genital, metabolic, white fat, CNS, muscle

Thyroid stimulating hormone receptor antibodies (TSI)->triggering->mimics TSH->+growth of thyroid gland
Pituitary->-ve expression of thyrotropic= Suppressed TSH
Heart->+ANP=+rate/contractility
Liver->+T1deiodinase, LDL receptors= +peripheral T3, -ve LDL
Bone->+psteocalcin, +ALP= +bone turnover
Genital->+SHBG, -ve testosterone, estrogen antagonism=-ve libido/erection, irregular menses
Metabolic->+FA oxidation, +Na/K ATPase= +thermogenesis
MSK->+SRCa2+ activated ATPase= proximal myopathy

20

Key factors in Grave's

Risk factors
Heat intolerance
Sweating
Weight loss
Papitations
Tremor
TachyC
Diffuse goitre
Opthalmopathy

21

Investigations in Grave's disease

TSH (suppressed)
Free T4 (+, not in T3 toxicosis/subclinical)
Free T3
T3RU, Free T4 index
FBC (normocytic normochromic)
UEC, Ca+ LFT+
Thyroid autoantibodies
If opthalmopathy->visual acuity testing, eye movements

May consider: RAIU, TIS, T U/S (highly vascular, diffuse, enlarged)

22

Triggering events in Grave's

Stress
Infection
Childbirth

23

What autoimmune conditions are associated with Grave's

Vitiligo, T1DM, Addisons

24

What is the typical age of Grave's patient

40-60 years

25

Initial management of Grave's/hyperthyroidism

Carbimazole
Propranolol (usually only until rendered euthyroid)
DIltiazem (when CI to beta blockers)

26

When is dosing reassessed

Every 3-6 weeks

27

Is dosing initially based on TSH, or T3/T4 and why

TSH can be suppressed for months after hyperthyroidism is corrected

28

When is the maximum chance of remission for Grave's

After 12-18 months of antithyroid medication

29

What are the options for subsequent therapy for hyperT

Continued antiT
Withdrawal
RI treatment
Thyroidectomy

30

When is surgery considered

Tracheal pbstruction/narrowing
Dysphagia
Stridor
Cosmetic