What is Endemic Goiter?
Diffuse goiter - it affects >5%Q of the population.
What is intrathoracic goiter?
If more than half of thyroid tissue is below the opening of thoracic cageQ.• Usually arises from lower pole of a nodular goiterQ.
What is primary intrathoracic goiter?
- Arise from accessory (ectopic) Q thyroid tissue located in the chest
- Supplied by intrathoracic blood vesselsQ
What is secondary intrathoracic goiter?
- Constitute majorityQ of mediastinal goiters
- Arise from downward extension of cervical thyroid tissueQ along the fascial planes of the neck and
- Derive their blood supply from the superior and inferior thyroid arteriesQ
Surgical approach for intrathoracic goiter?
- intrathoracic goiters can be removed via a cervical incisionQ.
- Indications of Median Sternotomy are –
- 1. Invasive thyroid cancersQ
- 2. Had previous thyroid operations and may have developed parasitic mediastinal vesselsQ
- 3. Primary mediastinal goiters with no thyroid tissue in the neckQ
T1/2 of various iodine Isotopes?
- I132 - 2.3 hoursQ
- I123 - 13 hoursQ
- I131 - 8 daysQ
Role of propranolol in thyroid storm?
- Most valuable measure in thyroid stormQ.
- Most of the symptoms are because of adrenergic over activity due to increased tissue sensitivity to catecholamines in hyperthyroidism.
- This increased sensitivity is due to increased number of beta receptorsQ.
MOA os Propylthiouracil in thyroid storm?
- Antithyroid drug of choice for thyroid stormQ
- Reduces hormone synthesis as well as peripheral conversion of T4 to T3Q
Ease of control of Hyperthyroidism in pregnancy?
- Most difficult to control in the first trimesterQ
- Easiest to control in the third trimesteQ
Fetal aplasia cutisQ.
Causes of Dancing Carotids?
- • Aortic regurgitationQ
- • ThyrotoxicosisQ
What is Wolff-Chaikoff effect?
Iodine induced hypothyroidismQ
What is Jod-Basedow’s effect?
Iodine induced hyperthyroidismQ
Limitations of beta-blockers in thyrotoxicosis?
- Do not significantly affect the thyroid statusQ, it reduces to some extent the conversion of T4 to T3.
- Do not correctQ the underlying metabolic abnormalities (i.e. does not affectt the oxygen consumption) Q
What is Plummer’s disease?
It is a ToxicAdenoma or hyperthyroidism from a single hyperfunctioning noduleQ
Graves disease etiology?
Stimulatory autoantibodies to TSH-RQ.
Clinical features of graves disease?
- Female - amenorrhea, decreased fertility and increased incidence of miscarriageQ
- Children - rapid growth with early bone maturationQ
- Old patients - CVS complications (AF and CHF)Q
Signs in Grave’s disease?
- • Overlying bruit or thrill at upper poleQ due to increased vascularity
- • Loud venous humQ in supraclavicular space
- • Ophthalmopathy (orbital proptosis) occurs in 50%, dermopathy in 1-2%.Q
- • Dermopathy is characterized by deposition of glycosaminoglycans leading to thickened skin in pretibial regionand dorsum of footQ (pretibial myxedema).
Complications of Radioactive iodine?
- Acute - HemorrhageQ (brain metastasis) • Cerebral edemaQ (brain metastasis) • Vocal cord paralysisQ • Nausea and vomitingQ • Bone marrow suppressionQ
- Long term – bone marrow suppression, leukemia, infertility
Treatment for curative intent is reserved in Graves disease?
- 1. Small, nontoxic goiters <40 gmsQ
- 2. Mildly elevated thyroid hormone levelsQ
- 3. Rapid decrease in gland size with antithyroid medicationsQ
Disadvantages of radioactive iodine?
- Progression of Grave’s ophthalmopathyQ
- Small increased risk of nodular goiter, thyroid cancer and hypoparathyroidismQ
- Unexplained increase in overall and cardiovascular mortalityQ
- Higher initial dose of 131I: Earlier onset and higher incidence of hypothyroidism
When are antithyroid drugs stopped in Graves disease before surgery?
Continued up to the day of surgeryQ.
Dose of Lugol’s iodine?
7-10 days preoperatively (three drops twice daily) Q
Mode of action of Lugol iodine?
Inhibit release of thyroid hormoneQ
Indications of Total or near-total thyroidectomy in Graves disease?
- • Patients with coexistent thyroid cancerQ
- • Who refuse RAI therapyQ • Have severe ophthalmopathy Q
- • Life-threatening reactions to antithyroid medicationsQ (vasculitis, agranulocytosis, or liver failure
Where should the vessels be ligated in thyroidectomy?
- Both superior and inferior thyroid vessels should be ligated close to the thyroid.
- Superiorly, to avoid injury to the external branch of the superior laryngeal nerve.
- Inferiorly, to minimize devascularization of the parathyroids (extracapsular dissection) or injury to the RLN.
Localization of parathyroid intraoperatively?
Parathyroids usually can be identified within 1 cm of the crossing of the inferior thyroid artery and the RLN.
When do features of hypocalcemia develop after parathyroid injury in thyroidectomy?
2-5 days after operationQ - circumoral and fingertip numbness and tingling tetany, carpopedal spasm and laryngeal stridor
Management of post-operative hypocalcemia?
• Asymptomatic with calcium level >8 mg/dl: No treatmentQ
Mild symptoms or calcium level <8 mg/dl: Oral calciumQ
- Severe Symptoms: IV calciumQ