Hypothyroidism
is a common endocrine disorder resulting from deficiency of thyroid hormone. It
usually is a primary process in which the thyroid gland produces insufficient
amounts of thyroid hormone. Hypothyroidism
commonly manifests as a slowing in physical and mental activity but may be
asymptomatic. Symptoms and signs of this disease are often subtle and neither
sensitive nor specific. Classic signs and symptoms, such as cold intolerance,
puffiness, decreased sweating, and coarse skin, previously reported in 90-97%
of patients, may actually occur in only 50-64% of younger patients. Many of the
more common symptoms are nonspecific and difficult to attribute to a specific
cause. Individuals can also present with obstructive sleep apnea (secondary to
macroglossia) or carpal tunnel syndrome. Women can present with galactorrhea
and menstrual disturbances. Consequently, the diagnosis of hypothyroidism is
based on clinical suspicion and confirmed by laboratory testing.
Physical
Signs
found in hypothyroidism are usually subtle, and their detection requires a
careful physical examination. Moreover, they are often dismissed as part of
aging; however, clinicians should consider a diagnosis of hypothyroidism when
such signs are present.
Central hypothyroidism (secondary or
tertiary) results when the hypothalamic-pituitary axis is damaged. Various
causes should be considered
:
- Pituitary adenoma
- Tumors impinging on the hypothalamus
- History of brain irradiation
- Drugs (eg, dopamine, lithium)
- Sheehan syndrome
- Genetic disorders
