Thyroid disorders Flashcards
Know how to make the diagnosis of hyperthyroidism and how to investigate the differential diagnosis of hyperthyroidism
Diagnose by symptoms, screen with TSH, if low, then FT4 and T3. Then what is the cause? Thyroid scan or I uptake, or Abs (TSH-R or TPO)
Know the causes of increased and decreased iodine uptake or 99mtechnetium thyroid scan uptake
Increased: Graves, Toxic adenoma or toxic multinodular goiter’ decreased: Thyroiditis (subacute - viral, painless - silent, Post-partum), hashimotos’, I excess. Painless, post-partum, and Hashimoto’s has TPO Ab. Grave’s has TSH-R Ab and TPO.
Know the three autoimmune manifestations of Graves’ disease
orbitopathy (proptosis), pretibial myxedema, acropachy(finger clubbing)
Know thepathophysiology of the autoimmune manifestations.
Genetic polymorphisms: HLA-DR, CTLA-4, PTPN22. T cell regulatory defect leading to production of TSH receptor antibodies in thyroid, bone marrow, lymph nodes. TPO antibodies also produced – may lead to thyroid destruction later
Know the therapeutic options for Graves’ disease
Drugs, about 20% long term remission but 30% relapse: PTU (better in 1st 1/3 of pregnancy), methimazole (stronger, longer T1/2). Near total thyroidectomy. Radioactive I (radiation about 24-48h, possible worsening of ophthalmopathy).
Signs/symptoms of thyrotoxicosis
Nervousness, palpitations, sweating, heat intorlerance, fatige, wt loss, dyspnea, increased appetite, eye symptoms; more rare: fixable hair and nails, increased BM, diarrhea, menstrual issues. High HR, goiter, tremors, skin chages, hyperactivity, bruit, lid lag and retraction, ophthalmopathy, A fib, onycholysis (nails peeling off due to cell turnover), vitiligo
Apathetic thyotoxicosis
Atypical presentation in elderly. Missing most other signs of hyper thyroid, mostly just A fib, wt loss.
Percent causes of thyroid ophthalmopahty
80% is graves. The rest is hashimoto’s or euthyroid.
Signs and symptoms of ophthalmopathy
Symptoms: Inflammatory – irritation, gritty, pain, watering, photophobia, periorbital edema, If optic nerve compression – decreased vision, Diplopia – due to eye muscle inflammation. Signs: Periorbital edema, Conjunctival edema (chemosis), injected (redness), Opthalmoplegia (eye muscle weakness), diplopia– muscle imbalance, Proptosis, Retina: papilledema
What causes lid retraction?
Proptosis - eyelid not big enough to get over it; and TH stimulates sympathetic activity which causes the eyes to open more.
What causes the ophthalmopathy? How does treatment of Thyroid help?
Not sure how, likely T cells infiltrating and attacking antigen in eye muscles. Hyperthyroid Tx does NOT influence course of eye disease. Tx for eyes not great: lubricants, tape shut; corticosteroids, orbital radiation; surgery on lids, orbital decompression (chunk of bone to allow for room for muscles), muscle balancing.
What is pretibial myxoedema?
aka Grave’s dermopathy. On shins or top of feet. Immune infiltration under skin. Feels hard and firm but painless. Give topical corticosteroids
Do pretibilal myxedema and acropachy regress with Tx of graves?
No! Continue to progress despite that, but can be treated separately.
Other causes of hyperthyroidism
Graves is number 1. Then, Toxic (hyperfunctioning) thyroid nodule(s), Silent (autoimmune; Hashimoto’s) thyroiditis and variants; Subacute thyroiditis (de Quervain’s thyroiditis) - stupid name, it’s painful.
Know the differentiating features (clinical, biochemical, radiological) between Graves’ disease, thyroiditis, and toxic nodules
Graves: Usually diffuse symmetrical goitre, Extrathyroidal autoimmune signs. Toxic nodule(s): Single nodule or irregular, lumpy (multiple nodules) goitre, No autoimmune signs
Dx of toxic nodules
Screen: suppressed TSH, then T4 T3. Do thyroid scan to see nodules. Negative TPO and TSH-R.
Silent thyroiditis
Aka transient hyperthyroidism Variant of Hashimoto’s. May cause hyper or hypo. Self-limiting, so don’t need Tx, give ß blockers to reduce symptoms. NO neck pain or tender thyroid. No systemic symptoms. WBC and ESR normal. Positive TPO Ab. Can go back to normal or drop to hypo after being hyper (followup).
Subacute thyroiditis (de Quervain’s)
Viral cause. Self-limiting. Exquisitely tender and painful thyroid, don’t want to be touched at all. Neck pain radiating to ear or jaw. Often preceded by upper respiratory infection. Prodrome: myalgia, malaise, fatigue. Fever. ESR elevated; WBC usually normal.. WBC count can be different. Transient hyper, then maybe hypo then maybe recover. Almost never happens again. Give ß blockers, analgesics, corticosteroids.
Postpartum thyroiditis
Variant of Hashimoto’s, after pregnancy. Can result from drop off of estrogen (anti-inflammation). Can be hyper, hypo, or hyper then hypo. Can get permanent hypo if no hyper phase, high TPO, or sever hypo.
Subclinical hyperthyroidism
Normal T3/T4, suppressed TSH. Usually normalizes, some progress to hyper. Higher risk of A fib, aggravate CHF, angina. Same cause as hyper, same Tx.
Know the causes of hypothyroidism
Endogenous: Most common: Hashimoto’s (autoimmune). Other autoimmune (painless or post-partum in the hypo phase). Subacute (viral) in hypo phase (rare). Congenital. Exogenous: overtreat Radioactive I, anti-thyroid drugs, surgery, higher I intake
Know the symptoms and signs of hypothyroidism
Fatigue, apathetic face, cool dry thick skin, periorbital edema, Weight gain, Cold intolerance, Constipation, Nausea / low appetite, slower reflexes, Menorrhagia (frequent/heavy), edema, Shortness and slowness of breath, diastolic hypertension depression, psychosis, Dry skin, Brittle hair and nails, Galactorrhea (rare), loss of outer 1/3 eyebrow. Severe: heart failure, coma, generalized edema
What is hashimoto’s?
Autoimmune destruction of thyroid follicles and spilling of stored TH. Can present with hyper, then euthyroid, then hypo (progressive). Goiter is common. TPO Ab. Nodules rare (from scarring). Can have some ophthalmopathy or polyglandular autoimmune syndrome.
Most common presentation of Hashimoto’s?
A euthyroid goiter with TPO Ab. Then hypothyroidism, then hyperthyroid phase (least common).
