History
Hypothyroidism is usually insidious in onset, with signs and symptoms slowly progressing over months to years. Most commonly, patients do not relate a history suggestive of transient hyperthyroidism secondary to increased T4 and T3 levels resulting from thyrocyte destruction. The time course is influenced by the rapidity of onset and the severity of the clinical state of hypothyroidism. The history may be suggestive of other autoimmune associations.
The presentation of patients with hypothyroidism may be subclinical, without any symptoms, and may be found simply from routine screening of thyroid function. The usual finding is an elevated TSH level. The early compensatory increase in TSH tends to maintain a nearly normal thyroid function and keeps the patient in a euthyroid state.
Patients most commonly present with nonspecific symptoms suggestive of overt hypothyroidism. Patients with long-standing, severe hypothyroidism could present in myxedema coma, precipitated by some major stress or infection.
Common, early presenting symptoms of hypothyroidism, such as fatigue, constipation, dry skin, and weight gain, are nonspecific. Weight gain due to hypothyroidism is usually no greater than 10% of the baseline euthyroid weight and is mostly attributable to fluid accumulation in interstitial tissues.
Other symptoms of hypothyroidism include the following:
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Cold intolerance
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Voice hoarseness and pressure symptoms in the neck from thyroid enlargement
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Slowed movement and loss of energy
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Decreased sweating
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Mild nerve deafness
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Peripheral neuropathy
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Galactorrhea - This may occur because of the increased prolactin levels.
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Depression, dementia, and other psychiatric disturbances
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Memory loss
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Joint pains and muscle cramps
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Hair loss from an autoimmune process directed against the hair follicles
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Menstrual irregularities (typically menorrhagia, infertility, and loss of libido) - Increased prolactin secondary to increased thyrotropin-releasing hormone (TRH) leads to decreased luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and to decreased response to gonadotropin-releasing hormone (GnRH); the result is anovulatory cycles with menstrual irregularities
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Sleep apnea and daytime somnolence - Obstructive sleep apnea in hypothyroidism is thought to be partly caused by hypofunction of upper airway muscles and weakness of the diaphragm.
Physical Examination
Physical findings are variable and depend on the extent of hypothyroidism and other factors such as age. Findings include the following:
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Puffy face and periorbital edema typical of hypothyroid facies
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Cold, dry skin, which may be rough and scaly - Skin may appear yellow but does not involve the sclera, which distinguishes it from the yellowing of jaundice due to hypercarotenemia
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Peripheral edema of hands and feet, typically nonpitting
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Thickened and brittle nails (may appear ridged)
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Hair loss involving the scalp, the lateral third of the eyebrows, and possibly skin, genital, and facial hair
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Bradycardia
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Elevated blood pressure (typically diastolic hypertension) - Most often, blood pressure is normal or even low
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Diminished deep tendon reflexes and the classic prolonged relaxation phase, most notable and initially described at the Achilles tendon (although it may be present in other deep tendon reflexes as well)
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Macroglossia
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The thyroid gland is typically enlarged, firm, and rubbery, without any tenderness or bruit; it may be normal in size or not palpable at all.
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Voice hoarseness
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Slow speech
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Impairment in memory function
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Peripheral neuropathy - This may be a mononeuropathy (as exemplified by carpal tunnel syndrome) or a polyneuropathy resulting from the involvement of several peripheral nerves, manifesting as paresthesia
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Ataxia - Ataxia from cerebellar dysfunction has been documented in hypothyroidism
