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
