L20- Endocrine Pathology II (thyroid) Flashcards
Thyroid gland:
- (1) origin
- (2) functional unit + product
- (3) other cells + function
- (4) T3/T4 serum binding proteins
1- floor of pharynx
2- follicle => T4/T3 (90%/9%)
3- C cells –> calcitonin
4- TBG, thryoxine-binding prealbumin (transthyretin), albumin
Thyroid follicle structure = (1)
C cell, aka (2), location -(3)
1- cuboidal / columnar cells surround colloid (storage form)
2- parafollicular cells
3- between follicles
List the thyroid functions (generally)
- many metabolic functions (catabolic mostly) ==> stimulates basal metabolic rate
- essential for neurological development (first 1.5 yrs mostly)
- inc sensitivity of CVS, CNS to catecholamines (SNS)
[Thyroid hormone control]
(1) from hypothalamus stimulates (2) to occur. The result of (2) will activate (3) type receptor in the thyroid gland to stimulate (4).
1- TRH
2- pituitary release of TSH
3- Gs receptor (inc cAMP)
4- T3/T4 production
Hyperthyroid Sxs:
- (1) general
- (2) GIT
- (3) CVS
- (4) unique / others
1- (SNS Sxs) weight loss, sweating, heat intolerance, fatigue, anxiety, **proximal neuropathy, lid-lag
2- diarrhea
3- palpitations, *AFib, high-output HF
4- goiter, menstrual disturbances, infertility, osteoporosis
define Thyrotoxicosis
endogenous (hyperactive thyroid) or exogenous (thyroid replacement drugs) excess thyroid hormone => classic hyperthyroid Sxs
list most common causes of hyperthyroidism
- **diffuse hyperplasia / Graves disease (most common)
- toxic adenoma
- toxic multinodular goiter
- thyroiditis
Grave’s disease = (1):
- Igs against (2) to cause (3)
- (4) are noticeable thyroid changes
- (5) are key Sxs
1- diffuse hyperplasia 2- HLA associated 3- binds and activates TSH receptors 4- goiter (diffuse enlargement) 5- exophthalmos, pretibial myxedema (non-pitting) [via glycoaminoglycan deposition]
describe Thyroiditis
1) Subacute/ De Quervain’s thyroiditis: pain (only disease with pain), tenderness, fever
2) postpartum thyroiditis (natural immunosuppressin in pregnancy)
Stage I- hyperthyroid
Stage II- hypothyroid (destruction)
Stage III- euthyroid
Hypothyroidism Sxs
- lethargy, tiredness
- cold intolerance
- dry, brittle hair, dry skin
- hoarseness
- weight gain
- slow relaxation of tendon reflexes, carpal tunnel
- constipation
- Xanthelasma
- psychosis
- angina, bradycardia
- generalized myxedema
Hyperprolatinemia (via excess TRH) –> menorrhagia, galactorrhea, infertility
list causes of hypothyroidism (primary, secondary)
Primary:
- Hashimoto’s / Autoimmune
- Iatrogenic (post-surgery, anti-thyroid drugs, radioactive iodine)
- congenital
- iodine deficiency
Secondary:
-pituitary or hypothalamic disorder
Hashimoto’s thyroiditis:
- associated with Ig(1) against (2) causing (3)
- (4) Abs are also involved
- high risk of (5) complication
1- IgG
2- HLA associated
3- dec hormone production + destruction of thyroid cells
4- antimicrosomal (antiperoxidase), antithyroglobulin
5- B-cell lymphoma (lymphocyte infiltration)
Hashimoto’s thyroiditis:
- (1) presentation
- occasional (2) may be initially present
- histology shows (3) change allowing for inc risk of (4)
1- hypothyroid Sxs, goiter
2- hyperthyroidism (Hashitoxicosis)
3- diffuse lymphocytic / plasma infiltration –> lymphoid follicles (germinal centers)
4- B-cell lymphoma
Congenital hypothyroidism:
- (1) causes
- (2) is main Sxs
1- anatomic defect, iodine deficiency, Dyshormonogenesis (thyroid hormone enzyme deficiency)
2- Cretinism: protruding tongue, dwarf with short limbs, coarse dry hair, lack of hair / teeth, mental retardation, pot belly (umbilical hernia)
describe Thyroid investigations (the main 2)
1) TSH measurement
- follow with T4/T3 levels
2) thyroid Igs
- antimicrosomal / antithyroid peroxidase) + antithyroglobulin (Hashimoto’s)
- TSI (thyroid stimulating immunoglobulins, Graves)
list the other Thyroid investigations
- TRH measurement
- Thyroid Isotope Scan (malignancies)
- Fine-needle aspiration (malignancies)
Goiter:
- (1) definition
- (2) Sxs
- (3) Types
1- visible enlargement of thyroid –> hypo-/hyper-/eu-thyroid
2- dysphagia, hoarseness
3- simple diffuse, simple mutinodular, solitary thyroid nodule
Sub-clinical hypothyroidism:
- (1) Sxs and PE
- (2) labs
- risk of (3) development
- associated with (4)
- (5) indicates Tx
1- hot flushes, mild goiter 2- elevated TSH, normal T4 3- hypothyroidism (Ig dependent) 4- Atheroma (endothelial dysfunction) 5- TSH >10 (normal is 5)
NTI:
- (1) definition
- (2) labs
- (3) causes
(non-thyroidal illness)
1- abnormal tests in severe illness
2- normal/low TSH, low T3, normal/low T4
3- TRH suppression, dec T4–>T3 conversion, transport/binding protein abnormality, inflammatory mediator effects
tumors of thyroid:
- mostly (1)
- (2) list malignant tumors
1- adenomas (benign)
2- (CAs are rare) papillary CA, follicular CA, anaplastic carcinoma, medullary carcinoma
Adenoma
- (benign/malignant)
- derives from (2)
- (3) mass description
1- benign
2- follicular epithelium (follicular adenomas)
4- discrete, solitary mass
tumors of thyroid:
- (1) Dx
- (2) Tx
- (3) post-Tx
1- tissue biopsy
2- Total Thyroidectomy + replacement T3/T4 (suppress TSH)
3- monitor TSH, thyroglobulin (both should be low)
Most thyroid cancers are (1), and (2) is the main characterization.
1- papillary CA (85%)
2- Psammoma bodies: papillae + calcifications
Papillary carcinoma (thyroid):
- pathogenesis is related to (1)
- (2) is the main risk factor
- spread via (3)
1- several gene mutations
2- ionizing radiation
3- LNs
Follicular carcinoma (thyroid):
- (1) is main risk factor
- (2) makes Dx difficult
- spreads via (3)
(5-15%)
1- dietary iodine deficiency
2- well-differentiated follilces (appears like normal)
3- capsular invasion and blood vessels (rarely LNs)
Anaplastic carcinoma of the thyroid:
- (1) definition
- (2) incidence rate and mortality rate
1- undifferentiated tumors of thyroid follicular epithelium
2- <5% thyroid tumors, ~100% mortality
Medullary carcinoma of the thyroid:
- cancer of (1)
- (2) causes
- (3) Tx
1- C cells / parafollicular cells
2- sporadic (80%), MEN (multiple endocrine neoplasia syndrome), inherited
3- total thyroidectomy + thyroid replacement + Calcitonin monitoring
