Thyroid disorders Flashcards
Lab findings of RTH (resistance to thyroid hormones
Elevated T3,T4 and normal/elevated TSH (unsuppressed)
Characteristic clinical feature of RTH (resistance to thyroid hormone)
Goiter without symptoms
Treatment of RTH (resistance to thyroid hormone)
No specific treatment
If hypothyroidism exists then treat with levothryoxine
List the causes of elevated total T4 with non suppressed TSH
1-resistance to thyroid hormone 2- familial dysalbuminemic hyperthyroxinaemia 3- neonatal period 4- iatrogenic (amiodarone, heparin) 5- TSH secreting pituitary tumor
Whats the diagnostic approach in suspected RTH (resistance to thyroid hormone)
1- Measure T4,T3,TSH (they are elevated with a non suppressed TSH)
2- measure T3,T4 in relatives
3-exclude TH transport defects
4- sequence for TRbeta mutation
5-exclude TSHoma by measuring serum alpha-SU
6- demonstrate a blunted TSH with the administration of extraneous TH
Why is there hyperlipidemia in hypothyroidism
T3 upragulates LDL receptor gene. Low T3 causes lower numbers of LDL receptors so that LDL stays in the plasma longer
Definition and cause fo thyroid dermopathy
Hypothyroid causes deposition of hyaluronic acid in the dermis which attracts water and causes non-pitting edema
(Pretibial myxedema is an exception seen in Graves’ disease)
Treatment of hypothyroidism
Levó-thyroxine (synthetic T4)
Monitor TSH until its normal to manage the dose
Whats The best initial test for a thyroid disorder
TSH because it provides more detailed info on the status of T3,T4. If they are elevated then TSH decreases in response. Plus its levels can raise and fall before T3, T4 fall or raise can be evident in the blood
Whats thyroid storm
When someone had a previous thyroid problem (adenomas, graves..etc) then an acute stressor (surgery, trauma, infection) happen, this triggers a surge of catecholeamines (epinephrine, norepinephrine, dopamine) which are dangerous.
Symptoms include, tachycardia, hyperglycemia, fever, delirium.
Central hypo/hyper thyroid lab findings
T4,T3 levels follow TSH levels.
which means LOW TSH causes LOW T4,T3
and High TSH causes High T4,T3
Definition an diagnosis of euthyroid sick syndrome (ESS)
Patients who are critically ill can have low TSH and T4,T3 (related to their critical illness). This is similar presentation to central hypothyroidism, so to differentiate between Euthyroid sick syndrome and central hypothyroidism we check reverse-T3. If its high then its ESS. If its low then its central hypothyroidism
Causes of hypothyroidism
PRIMARY:Iodine deficiency, iatrogenic (surgical), Hashimoto’s thyroiditis (and other thyroiditis), wolf-chaikoff effect (in response to a load of iodine), lithium, congenital, infiltrative disorders, overexperssion of type 3 deiodinase
Secondary(central): hypopituitarim , hypothalamic disease, cancers (mass effect, craniopharengioma)
Extra thyroidal: resistance to TH
When do you measure free T3, total T3 for diagnosis
Following and diagnosing thyrotoxicosis
What are anti-thyroid antibodies and anti-thyroid peroxidase antibodies used for
Anti thyroid antibody is used as a marker for CHRONIC thyroiditis
Anti thyroid peroxidase antibody correlates with hypothyroidism
What do we use to monitor Graves’ disease
TSI thyroid stimulating immunoglobulin
TBII TSH binding inhibitory immunoglobulins
Whats the HLA associated with increased risk of thyroiditis
HLA-DR polymorphism (DR3,DR4,DR5)
Signs and symptoms of hypothyroidism
Symptoms Weakness Dry skin Bradycardia Constipation Weight gain Confusion (hyponatremia caused be increased ADH caused by hypothyroidism) Hoarse voice Parasthesia
Signs Cool, dry skin Puffy face, hands and feet (myxedema) Alopecia Peripheral edema (secondary to myxedema) Delayed tendon reflexes Carpal tunnel s
Whats myxedema coma
Coma caused by severe hypothyroidism, treat with levo thyroxine, and supportive therapy
Treatment of graves diseas
BB and thionamides as an inicial management. Thionamides are [PTU and methimazole] they inhibit TPO thyroidperoxidase. In pregnant woman with graves use only PTU.
Radioiodine ablation of the thyroid (contra in pregnancy)
Surgery thyroidectomy
Graves’ disease pathophysiology
antibodies that bind to TSH receptors on the thyroid and stimulate them
Most specific symptoms of graves disease
Exophthalmus
pretibial edema
Pathophysiology and treatment of graves ophthalmopathy
Autoimmune, TSH activates lymphocytes which induce inflammation and collagen deposition this is why its treated with steroids
Pathophysiology of graves pretibial edema
Inflammation induces fibrosis and collagen deposition plus glycosaminoglycans deposition in muscle which sucks water in and causes myxedema
Graves eye sings
Staring gaze Lid retraction Lid lag Potsis Exophthalmus Conjunctivitis Opthalmoplegia
Whats the “NO SPECS” scoring system
System to evaluate ophthalmopathy
0= No symptoms or signs 1= Only signs (lid retraction or lag) no symptoms 2= Soft tissue involvement (peri orbital edema) 3= Ptosis (>22mm) 4= Extraocular muscle involvement (diploid) 5= Corneal involvement 6= Sight loss
Subclinical hyperthyroidism, definition and do you treat it?
TSH decreased but normal T3,T4
And no signs nor symptoms.
Only treat younger patient or older patients that have persistent lower than normal TSH/patients with cardiac disease, osteoporosis, or patients with symptoms
What are the most common causes of subclinical hyperthyroidism
Excessive thyroid hormone replacement
Thyroid gland autonomy: adenomas , goiter , graves
Jod-basedaw phenomenon
Hyperthyroidism in patients who commonly live in areas with low iodine. If you give those individuals iodine they will develop hyperthyroidism
Also happens with patients with a thyroid adenoma, if you give them an idodine load, it will cause the adenoma to reales more TH and cause thyrotoxicosis
Amiodarone effect on the thyroid
Type 1: those who have a previous thyroid disease (graves, adenomas) it will cause hyperthyroidism
Type 2: in those who dont have previous thyroid siseasen,, the direct toxic effect of amiodaron on thyroid cells causes destructive thyroiditis (thyroiditis usually presents initially as hyperthyroidism then euthyroid state then hypothyroidism
It can cause hypothyroidism by two mechanisms:
1- wolf chaikoff effect
2-similar to T4 which inhibits 5’deiodinase that causes the peripheral conversion of T4 to T3 (the more potent form)
Symptoms of acute thyroiditis
Thyroid pain Erythema in the thyroid area Fever Systemic fever symptoms Small, tender goiter Dysphasia
Diagnosis of acute thyroiditis
Erythrocytes sedimentation rate Fine needle aspiration Polymorphonuclear lymphocyte infiltrates White blood cell count Culture of the sample
Whats subacute de Quervains granulomatous thyroiditis and how do you diagnose it
Subclinical thyroiditis with granulomas that’s normally self limited. Presents with painful and enlarged thyroid, with the pain radiating to the jaw, malaise, and symptoms of Upper respiratory tract infection. important feature that its TENDER
Diagnosis with :
Measuring erythrocytes sedimentation rate
Low uptake of iodine
FNA biopsy shows granulomas
Treat with NSAIDs and manage symptoms if present (thyrotoxicosis) [its SELF LIMITED]
Whats silent thyroiditis
Usually subclinical, it happens after pregnancy, and is associated with TPO antibodies with more prevalence in patients with type 1 diabetes
What are the features of Hashimoto’s thyroiditis and its treatment
Non tender, asymmetric, fixed goiter (Nasty As Fuck)
Treated with TH replacement therapy (levothyroxine) (presentation says tamoxifen which is an estrogen receptor modifier??? (dafuq))
Whats sick euthyroid syndrome
Decreased in thyroid hormones due to their critical illness (ICU patient) (not related to central nor primary hypothyroidism)
Factors that alter thyroid function in pregnancy
Exacerbation of underlying autoimmune disease
Increased TH demand by placenta(woman in low iodine areas are at risk of developing goiter)
HCG increased which stimulates TSH-Receptor
Estrogen induced raise in blood glucose levels
increase idodine urine excretion
Whats the definition of goiter
Increased in thyroid size caused by deficiency of iodine (most common), biosynthetic defect, autoimmune disease/nodular disease
It can be single or multiple, functional or nonfunctional
Whats diffuse nontoxic goiter
Goiter with no nodules that happens with iodine deficiency. Treat with iodine
Indication for thyroid surgery
Malignancy
Aesthetic
Compressive symptoms
Repeated non diagnostic FNA
whats Hyper functioning solitary nodule, how do you treat it?
A solitary nodule that is mutated with over functioning TSH-r receptor so that it keeps synthesizing TH while the pituitary senses this and lowers TSH, the rest of the thyroid becomes hypofunctioning while the adenoma keeps overproducing TH
Since its the only one taking iodine, treat with radioiodine that will spare the rest of the thyroid
Thyroid ultrasound exam suspicious signs include..
Larger than 1cm Hyper vascularization Hypoechoic Rapidly growing More tall than it is wide Micro calcification
These are the criteria for FNA (not every goiter/nodule gets a FNA)
What are Bethesda classification for thyroid cytology diagnostic category risk of malignancy
No diagnostic or unsatisfactory (repeat FNA) 1-5%
Benign. 2-4%
Atypia or follicular lesion of unknown significance 15-20%
Follicular neoplasm. 20-30%
Suspicious malignancy. 60-75%
Malignant. 90-100%
What are the risk factors of thyroid carcinoma
Radiation exposure Vocal cord paralysis Male gender Size >4 Age <20, >65 Family history of MEN2 Lateral cervical adenoma they Nodule extension to adnusent structures
Whats the most common thyroid cancer
Papillary carcinoma (derived from follicular cells)
Who is most likely to develop anaplastic thyroid cancer
Females more often, age older than 65
EU-TIRADS indication for high risk features of a neoplasm
Irregular shape
Irregular margins
Microcalcification
Hypoechogenicity
