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