Endocrine Flashcards by Satia Babu

Development of upper parathyroid glands

Arise from fourth branchial arch

Usually found at the back of the thyroid above the inferior thyroid artery

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Development of the lower parathyroid glands

Arise from the third branchial arch

Usually in association with thyrmus

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Level of the thyroid glands

Lie on front of trachea and larynx at C5-C7

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Superior thyroid artery

Branch of external carotid artery

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Inferior thyroid artery

Branch of thyrocervical trunk of subclavian artery

As the inferior thyroid artery appraoches the galdn it normally passes in front of the recurremt laryngeal nerve

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Lymphatic drainage of the thyroid

Pretracheal and mediastinal nodes

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Veins of the thyroid

Superior
Middle
Inferior
.. thyroid veins

S+M into the internal jugular and ITV drains into brachiocephalic

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Innervation of the intrinsice muscles of the larynx

Recurrent laryngeal nerve supplies all of them except Cricothyroid (exterior branch of superior laryngeal)

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Innervation of the cricothyroid muscles

External branch of the superior laryngeal nerve

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Innervation providing sensation above the vocal cords

Internal branch of the superior laryngeal nerve

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Innervation providing sensation below the vocal cords

Recurrent laryngeal nerve

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Non-toxic multinodular goitre

Multiple nodules
Caused by iodine deficiency

If biochemistry normal, no need for radio-isotype uptak e scan

Mx: Thyroidectomy and replacement

Can become toxic: a long-standing non-toxic goitre develops hyperactive nodule(s) that function independently of TSH levels

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Management of hashimoto’s

Replacenebt thyroxine

Thyroidectomy seldom needed and carries higher riusk of recurrently laryngeal nerve injury due to firmness of gland

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Firm painless swelling and tracheal compression

Riedel’s thyroiditis

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Mx: Aspirated cysts that do not re-fill with negative cytology

OP follow-up

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Residual aspirate or blood-stained aspirare

Suspect Papilllary carcinoma

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FNAC cannot distinguish bewteen…

cytopathologist cannot distinguish between a follicular adenoma and follicular carcinoma

Histopath needed

Primary thyrotoxicosis

Grave’s Disease

Toxic multi-nodular goitre

Toxic Adenoma

Management of primary thyrotoxicosis

Block and replace
Carbimazole (15mg QDS) and Thyroxine

Radio-iodine

Surgery
-Carbomazole used pre-op to render euthyroid
-B-blockers used pre-op to decrease vascularity
-B-blockers continued 7 days post op to avoid effects of thyroid storm

Most common thyroid cancer

Papillary carcinoma (50%)

Papillary carcinoma

Most prevalent before the age of 40
Psammoma bodies, thyroglobulin and orphan Annie
Slow-growing solitary growth

Lymphadenipathy palpable in 1/3

Complex papillary folds lined by several layers of cuboidal cells project into cystic space

Mx:
Thyroxine replacement to supress TSH

Commonly multifocal, so bilateral total lobectomy

Microscopic disease (< 1cm and unifocal) and tumours with favourable histology and < 2cm in size may be treated by single lobectomy

Radio-isotype scan post-op to detect possible mets

10-year survival rates approaching
90%

Follicular carcinoma

30% of thyroid carcinomas
Berry sign and thyroglobulin
Commonest age 30-50 yrs

Presents as a solitary thyoid mass

Haematogenou spread common, lymph node spread rare

Malignant cells are arrange dinto solid mass with rudimentary acini

Mx:
Total thyroidectomy with sparing of parathyroids

Post-op radio-isotype scan, use radio-ionide to treat mets

Replace with T3 and then T4 to supress TSH

Thyroglobulin should be undetectable - if found indicates recurrence

10-year survival rate is 75%.

Anaplastic carcinoma

Elderly women

Highly malignant

Peri-neural invasion –> recurrently laryngeal and cervical sympathetic (horners)

Pulmonary metastasis common

Mx
Surgery rarely appropriate, but can used to relieve tracheal compresison

External bean radiotherapy

Medullary carcinoma

Parafollicular C Cells - Raised Calcitonin

MEN II (Sipple’s Syndrome)

Hard enlargement of one or both thyroid glands

50% have cervical lymph node invasion

Pre-Op CT screening for phaeochromocytoma

Ret - proto oncogene

Mx
Total thyroidectomy and, if the calcitonin
level is raised, dissection of the lymph nodes in the
central compartment of the neck (levels 6 and 7).

Structures divided durng thyroidectomy

Travserse skin incision 2cm above sternal notch Longitudinal division of fascia Separation of strap muscles (upper half) Each lobe is mobilized by dividing the vessels supplying the superior pole, the middle and inferior thyroid veins, and the inferior thyroid artery

Damage to the external branch of the superior laryngeal nerve

Damaged whilst securng superior thyroid pedicle --> inability to tense vocal cords: weaker voice with ptich-range change --> lack of sensation to mucous membrane of upper larynx: allows foreign bodies to enter larynx more readily

Damage to the recurrent laryngeal nerve

Division --> paralsysis of vocal cords in cadaveric position Normal cord on the other side compensates by crossing the midline in phonation, but the voice is altered in timbre, hoarse, weak and breathy Some degree of stridor

Bilateral recurrent laryngeal nerve injury

Bilateral nerve injury results in stridor and ineffective coughing when the endotracheal tube is withdrawn at theend of the operation The tube is reinserted immediately and, if there is no early improvement, tracheostomy may be required. The paralysis is originally flaccid, but fibrosis draws the cords together and, even if tracheostomy has been avoided, increasing dyspnoea on exertion may be troublesome.

Blood supply to the parathyroids

Inferior thyroid artery

Development of anterior pituitary

The anterior pituitary develops from an epithelial outgrowth from the pharynx (Rathke's pouch).

Complications of transcranial approach to hypophysectomy

Anosmia Diabetes insipidus

Development of adrenal cortex

Mesoderm

Development of adrenal medulla

Chromaffin ectodermal cells of the neural crest

Adrenal phaeochromocytomas

Secrete noradrenaline and adrenaline

Extra-adrenal phaeochromocytomas

Secrete noradrenaline only

Adrenal ‘incidentaloma’

If non-functioning and <3.5 cm in diameter, further investigation and exploration are unwarranted

Indications for adrenalectomy

Cushing's syndrome caused by adrenal tumours Cushing's disease not controlled by pituitary surgery Conn's syndrome caused by adrenal tumour Phaeochromocytoma

APUD Cells

Have capacity to store and synthesise amines: ATCH, catecholamines, calcitonin, secretin, gastrin, cholecystokin, enteroglucagon, somatostatin, VIP Found in: -anterior pituitary -adrenal medulla -thyroid gland -intestine

MEN I

Hyperplasia or adenaomas of the: -Pancreatic islets -Parathyroid -Anterior pituitary There may also be non-functioning tumours of the thyroid, pituitary, adrenal cortex and soft tissues (lipomas), and functioning carcinoid tumours of the gut or lungs. Mutations in the MENIN gene on chromosome 11

MEN II

Medullary carcinoma of the thyroid Phaeochromocytoma Parathyroid hyperplasia Ret proto-oncogene chromosome 10

Urinary 5-hydroxyindolaecatic acid

Carcinoid disease

Carcinoid syndrome

HAS TO HAVE METASTASISED TO LIVER Periodic flushing Diarrhoea Bronchoconstriction Wheezing Red-purple discoloration of the face Right-sided heart disease, notably pulmonary stenosis -> death