| Aspect | Hypothyroidism | Hyperthyroidism |
|---|---|---|
| Metabolic | ๐น Cold intolerance, โ sweating | |
| ๐น Weight gain (โ basal metabolic rate โ โ calorigenesis) | ||
| ๐น Hyponatremia (decreased free water clearance) | ๐น Heat intolerance, increased sweating | |
| ๐น Weight loss (โ synthesis of Na+/K+-ATPase โ โ basal metabolic rate โ โ calorigenesis) | ||
| Skin/Hair | ๐น Dry, cool skin (due to decreased blood flow) | |
| ๐น Coarse, brittle hair, diffuse alopecia | ||
| ๐น brittle nails | ||
| ๐น Puffy facies | ||
| ๐น Generalized nonpitting edema (myxedema) due to increased GAGs (glycosaminoglycans) in interstitial spaces, increased osmotic pressure leading to water retention. | ๐น Warm, moist skin (due to vasodilation) | |
| ๐น Fine hair | ||
| ๐น Onycholysis | ||
| ๐น Pretibial myxedema in Graves disease โ characteristic feature. | ||
| Ocular | ๐น Periorbital edema | ๐น Ophthalmopathy in Graves disease (including periorbital edema, exophthalmos) |
| ๐น lid lag/retraction (increased sympathetic stimulation of superior tarsal muscle) | ||
| Gastrointestinal | ๐น Constipation (decreased GI motility) | |
| ๐น Decreased appetite | ๐น Hyperdefecation/diarrhea (increased GI motility) | |
| ๐น Increased appetite | ||
| Musculoskeletal | ๐น Hypothyroid myopathy (proximal weakness, increased CK) | |
| ๐น Carpal tunnel syndrome | ||
| ๐น Myoedema (small lump rising on the surface of a muscle when struck with a hammer) | ๐น Thyrotoxic myopathy (proximal weakness, normal CK) | |
| ๐น Osteoporosis/increased fracture rate (T3 directly stimulates bone resorption by increase activation of osteoclast). | ||
| Reproductive | ๐น Abnormal uterine bleeding, decreased libido, infertility | ๐น Abnormal uterine bleeding, gynecomastia, decreased libido, infertility |
| Neuropsychiatric | ๐น Hypoactivity, lethargy, fatigue, weakness, depressed mood | |
| ๐น Decreased reflexes (delayed/slow relaxing)โ characteristic feature. | ๐น Hyperactivity, restlessness, anxiety, insomnia | |
| ๐น Fine tremors (due to increased ฮฒ-adrenergic activity) | ||
| ๐น Increased reflexes (brisk) | ||
| Cardiovascular | ๐น Bradycardia | |
| ๐น Dyspnea on exertion (โ cardiac output) | ๐น Tachycardia, palpitations, arrhythmias (e.g., atrial fibrillation). | |
| ๐น Dyspnea, chest pain | ||
| ๐น Systolic hypertension due to |
1. increased number and sensitivity of ฮฒ-adrenergic receptors
2. increased expression of cardiac sarcolemmal ATPase,
3. Decreased expression of phospholamban |
| Labs | ๐น โ TSH (if primary)
๐น โ free T4
๐น Hypercholesterolemia (due to โ LDL receptor expression) | ๐น โ TSH (if primary)
๐น โ free T3 and T4
๐น โ LDL, HDL, and total cholesterol |
**Onycholysis**
Pretibial myxedema in Graves disease
**Periorbital edema**
**Myoedema**
More on Cardiovascular effects of hyperthyroidism
Common causes of myopathy
<aside> ๐ก The most common cause of inadequate thyroid hormone levels in infants with treated congenital hypothyroidism is rapid growth, which increases the physiologic need for thyroid hormone.
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<aside> ๐ก Clinical manifestations of congenital hypothyroidism may not be present at birth due to the transplacental transfer of small amounts of maternal T4.
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<aside> ๐จ Intellectual disability is irreversible, so we rapidly initiate treatment of congenital hypothyroidism with levothyroxine to prevent it.
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<aside> ๐ Any form of thyroiditis is associated with low iodine uptake, โ thyroglobulin level.
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