Thyroid Flashcards
Hyperthyroidism
Excess thyroid hormone due to-
Excess production: Grave’s disease, toxic MNG, toxic adenoma, pituitary adenoma,
Excess release of preformed hormone from the gland: Hashimoto’s (initial phase), iatrogenic (large doses of thyroid hormone supplements), hamburger.
Grave’s Disease
(Diffuse Toxic Goiter)
Li, postpartum state, Iodine excess- triggers- CD4+ activation-B lymphocytes activated- Produce Ab against the TSH receptor in the thyroid gland which mimics TSH- Stimulates production of thyroid hormones- HYPERTHYROIDISM.
A/w- T1DM, pernicious anemia, MG, Addison’s
Gross- Diffusely enlarged
Micro- Columnar cells (instead of cuboidal) with scanty, vacuolated cytoplasm
Signs- Eye, skin, thyroid acropachy (subperiosteal bone formation)
Ix: TFT- Low TSH, High T3, T4
If eye signs present- no further Ix reqd. - otherwise- RAI I123< Tc99 uptake.
TSH R-Ab
Rx:
1. Anti thyroid drugs-
PTU- 100-300mg TID- Preferred during preg/ breastfeeding. Inhibits peripheral conversion of T4-T3.
Methimazole- 10-30mg TID- Aplasia
Agranulocytosis (sorethroat), fever, skin rash, vasculitis
Block and replace regimen
Propranolol- 20-40mg QID - given if CVS disorder+/ HR>90bpm
Only anti thyroid drugs are sufficient if: Low TSH R Ab titers are low, mildly elevated T4 levels, rapid reduction in thyroid swelling and symptoms with start of Rx. Otherwise anti thyroid drugs given to make the patient euthyroid before surgery.
- RAI- Euthyroid within 2 months
I131<I123< Tc99
Contraindicated in:
Young
Ophthalmopathy +
Pregnant/ wants to conceive within 6 months/ breastfeeding - Surgery
Near total/ total thyroidectomy
Pregnant/ breastfeeding/ wants to conceive within the next 6 months
Compression symptoms
Unable to tolerate/ resistant to all anti thyroid drugs
Patient made euthyroid before surgery- Anti- thyroid drugs given until the day of surgery, Lugol’s Iodine 3-0-3 started 7-10 days before surgery- given to reduce vascularity of the gland, decrease thyroid hormone production by Wolf Chaikoff effect.
Hartley Dunhill procedure- Total lobectomy on one side with 4g gland left of the opposite side- in case of recurrence only one side needs to be reopened.
Procedure of choice- Near total/ total thyroidectomy.
Hypothyroidism
Primary- Issue within the thyroid gland
Secondary- Issue with the pituitary gland
Tertiary- Issue with the Hypothalamus
Riedel’s Thyroiditis
Hashimoto’s thyroiditis
Acute suppurative thyroiditis
Thyroid gland- naturally resistant to infection- d/t extensive blood supply, lymphatic drainage, fibrous capsule
Etiology:
1. Pyriform sinus fistula
2. Penetrating trauma to thyroid gland
3. Immunosupression
4. Direct spread from a primary infectious source in the body via blood/ lymphatics
Preceeded by URTI/ OM
Neck pain- radiating to jaw/ ear, fever, chills, odynophagia, dysphonia.
Complications-
Dx: Increased TLC, FNAB- C/S, Stain
Kids with recurrent thyroiditis- Suspect pyriform sinus fistula- Flexible transnasal fiberoptic laryngoscopy- visualise the opening of the sinus tract- electrocauterise
i.v antibiotics, abscess drainage- if conservative fails- thyroidectomy.
Toxic multinodular goiter
Prior h/o MNG- with time few of theses nodules become autonomous- cause hyperthyroidism.
Similar to Grave’s- without extrathyroidal manifestations.
TSH low, elevated T3, T4.
Total or near total thyroidectomy
Seldom RAI- RAI used in old patients with poor surgical outcomes. High doses of RAI reqd so avoided.
Toxic Adenoma
Single hyperfunctioning nodule- Symptomatic when nodule >3cm.
RAI- hot nodule
Young patients with larger nodules- Lobectomy
Thyroid storm
Hyperthyroidism+ fever+ CNS agitation/ CVS/ GI dysfunction
Precipitated by surgery (thyroid/ non thyroid), illness, abrupt cessation of anti thyroid Rx, exposure to Iodine/ iodine containing substances (contrast/ amiodarone)-
Rx:
1. O2- stabilise
2. PTU- Prevent peripheral conversion of T4-T3
3. Beta blockers- Prevent peripheral conversion of T4-T3, decrease hypothyroid symptoms
4. Steroids- To decrease effect of catecholamines
5. Lugol’s iodine- To produce Wolf Chaikoff effect- reduce I uptake for further thyroid hormone production by internalisation of sodium-I symporter.
Subacute thyroiditis
Post viral inflammatory response
Presentation similar to that of acute suppurative thyroiditis
Gland could be painful or painless.
4 phases- Hyperthyroid (release of synthesised and stored thyroid hormone from the gland after being destroyed); Euthyroid; Hypothyroid; Resolves- Euthyroid.
Painful- H/o URTI, tender firm gland. ESR>100
Conservative management
Painless-
Normal/ min enlarged gland, firm, non tender, ?AI origin/ postpartum/ sporadic.
ESR Normal
Goiter
Solitary thyroid nodule
Genetics in thyroid CA
Papillary thyroid cancer
Follicular thyroid cancer
Medullary thyroid cancer
Anaplastic thyroid cancer
Postop management and follow up of differentiated thyroid cancer
