S17C224 - Thyroid disorders: Hyperthyroidism and Thyroid storm

Question 1

T4/T3 ratio

Answer 1

normally 20:1

-T4 is converted to T3 peripehrally, T3 is 3x more potent than T4

Question 2

Hyperthyroidism

Answer 2

-excess homrone resulting only from thyroid gland hyperfunction

Question 3

Thyrotoxicosis

Answer 3

-excess thyroid homrone originating from any cause (include thyroid OD)

Question 4

Thyroid storm

Answer 4

• extreme manifestation of thyrotoxicosis

- caused by either adrenergic hyperactivity or altered peripheral response to thyeroid hormone

Question 5

Causes of HeTH/thryotoxicosis

Answer 5

Primary:

• graves dz: toxic diffuse goiter, ophtalmopathy, local dermopathy
• TMG (multinodular goiter)
• TNG (nodular - adenoma - goiter) : enlarged thyroid with small rounded mass/masses and overproduction of thyroid

Secondary:

• thyrotropin-secreting pituitary adenoma
• thyroiditis - inflm of gland
• hashimoto thyroiditis - initally overacte but then followed by hypothyroid
• subacute painful thyroiditis
• ” painless thyroiditis
• radiation thyroiditis

Other: ectopic thyroid tissues, throid Ca. with mets, HCG (molar pregnancy), amiodarone (contains iodine so can cause thyrotoxicosis or HoTH), OD

Question 6

Thyroid storm

Answer 6

Precipitants: infxn, DKA, thyroxine OD, CVA, surgery, stress, parturition, eclampsia, trauma, MI, meds
-the stress increases the effect of thyroid hormone by freeing up more hormone from binding sites and increasing sensitivity of receptors

Question 7

Thyroid storm: physical exam

Answer 7

Consitutional: lethary, weakness, heat intolerance, diaphoresis, fever, wt loss
Neuropsychiatric: emotional, anxiety, confusion, coma, psychosis, tremor, muscle wasting, hyperreflexia, periodic paralysis
Endocrine: neck fullness, tenderness, bruit
Cardioresp: dyspnea, palpitations, chest pain, widened pulse pressures, systolic HTN, sinus tach, a fib/flutter, CHF, waterhammer pulse
GI: diarrhea
GU: oligomenorrhea, decreased libido, gynecomastia, telangiectasia
Gyne: menorrhagia, irregularity, decr pubic hair
Heme: pale skin, anemia, leukocytosis
Derm: Hair loss, pretibial myxedema, warm, moist skin, palmar erythema, onycholysis
-exophalmos

Question 8

Thyroid storm presentation

Answer 8

FEVER
TACHY
-arrhythmia, CHF
-agitated, confused, delirium, stupor, coma, Sz

Question 9

Thyroid storm: DDx

Answer 9

• sepsis
• sympathomimetic
• heat exhaustion/stroke
• DTs
• malignant hyperthermia
• malignant neuroleptic syndrome

Question 10

Secondary hyperthyroidism: labs

Answer 10

-TSH will be high b/c pituitary is producing it

Question 11

Thyroid toxicosis: labs

Answer 11

• low TSH with elevated T4 confirms it

- low TSH with normal T4 but elevated T3 also confirms it

Question 12

Grave’s: Dx

Answer 12

• do thyroid antibody titers (thyroid peroxidase/thyroglobulin)
• thyroid stimulating Abs can be detected
• other labs:
• hypergylcemia
• hypercalcemia
• raised liver enzymes

Question 13

Thyroid storm: Tx

Answer 13

1. supportive
2. inhibition of thyroid hormone release (thionamides - PTU or methimazole)
3. inhibition of hormone production (give 1h after step 2, lugol soln or iodide unless iodine-overload or amiodarine induced thyrotoxicosis, instead give lithium)
4. peripheral beta-adrenergic blockade (esmolol) or give reserpine and guanethidine if pt asthamatic and can’t have BB
5. preventing peripheral conversion of T4 to T3 - HCT or dex
6. treat precipitating event
7. definitive: radioactive iodine ablation tx

• also give thiamine
• cholestyramine inhibits T4/T3 reabsorption (enterohepatic circulation)
• other tx: plasmapheresis and PLEX