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
