Clinical Features of Hypothyroidism

Hypothyroidism: Clinical Features and Associated Disorders

Clinically, the onset of hypothyroidism may range from subtle and insidious findings to florid psychosis. The general examination features of hypothyroidism are numerous:

1) Subjective: Fatigue, somnolenee, eold intoleranee, syneope, exertional dyspnea, weight gain, arthralgias, nausea, anorexia, indigestion, eonstipation, menstrual abnormalities;

2) Objective: Bradyeardia, hair changes (sparse, eoarse, dry, brittle), puffy face, loss of lateral aspeets of the eyebrows, penorbital edema, maeroglossia, voiee deepening and hoarsening, skin ehanges (sealy, thiek, doughy, eoarse, dry, earotenemia), bnttle nails, nonpitting edema, galaetorrhea, effusions

CNS features include forgetfulness, inattention, apathy, and slowing of speech, movement and mentation. These features may mimic depression. Seizures, personality changes, psychotic states, coma, and dementia may also be clinically apparent. Cerebellar ataxia is seen in 5 to 10 percent of patients, and may be the presenting sign (so-called myxedema staggers). A psychotic presentation (myxedema madness) characterized by agitation, disorientation, delusions, hallucinations, paranoia, and restlessness is observed in approximately 3 to 5 percent of patients. Myxedema coma is extremely rare, and its characteristic features include extreme hypothermia, seizures (the presenting manifestation in nearly 20 percent of patients ), respiratory depression, and areflexia. Death can occur when early recognition and prompt treatment are lacking. Dementia may develop when hypothyroidism is severe. Except for the marked increase in the number of hours these patients remain asleep or resting, the clinical features of the dementia are similar to those secondary to other causes.

Peripheral neuromuscular features include cranial and peripheral neuropathies, prolonged reflex relaxation time (up to 85 percent of hypothyroid patients), and myopathy. Visual field defects can occur when pituitary enlargement causes hypothyroidism with concomitant chiasmal compression. A facial mononeuropathy, due to nerve entrapment in the fallopian canal of the temporal bone, may rarely occur. Although sensorineural hearing loss has been reported to correlate with the degree of hypothyroidism and has a high incidence among patients with congenital

Hypothyroidism, its reported incidence among adult hypothyroid patients varies. Minor evidence of polyneuropathy, such as distal lower extremity sensory dysfunction and absent ankle jerks, is observed in approximately 10 percent of patients, and rarely, a moderately severe sensorimotor polyneuropathy has been described. Carpal tunnel syndrome (i.e., median mononeuropathy at the wrist) occurs in 15 to 30 percent of hypothyroid patients, is usually bilateral, and is the most common mononeuropathy encountered.

Myopathy can be a feature of hypothyroidism and manifests with proximal muscle weakness. Regardless of the cause of the hypothyroidism, weakness is observed in about one third of these patients. Increased muscle size and firmness, which is most obvious in the limb musculature, as well as slowed muscle contraction are important features to identify. Exertional pain, stiffness, and cramps may be noted, and myoedema may be observed. Myoedema, a mounding of the muscle in response to direct percussion, is painless and electrically silent, and occurs in one third of hypothyroid patients. Difficulty relaxing the hand grip and exacerbation by cold weather may suggest myotonia. However, unlike myotonia, hypothyroid myopathy involves a slowness of muscle relaxation and contraction, and resolves with correction of the hypothyroid state. Although sleep apnea is usually of the obstructive type, other possibilities include a central abnormality, chest muscle weakness, and blunted responses to hypoxia and hypercapnia. Reports have associated hypothyroidism with SIADH, idiopathic intracranial hypertension, and myasthenia gravis.