THYROID GLAND

The thyroid may be smooth, lobulated, or rarely nodular. In thyrotoxicosis associated with nodular goiters, the hyperfunctioning tissue may reside between the nodules, ¹⁶³ which would constitute Graves' disease in a nodular goiter. Often the surface is lobulated, and the upper poles may seem to contain nodules above the site of entry of the superior thyroid artery. The diffuse toxic goiter is usually more or less symmetric. The size is related, but not closely, to the severity of the disease. It varies from the barely palpable normal (15 - 20 g) to an enlargement of six times normal (100 g) or, rarely, even more, but averages about 45 g. The near symmetry and usually moderate size of the diffuse goiter of Graves' disease make it somewhat less unsightly than many of the nodular goiters. It is commonly stated that the gland is not palpable in 1% of cases, either because the thyroid is actually smaller than ususal or because it is beneath the manubrium. However, in the presence of thyrotoxicosis, a small or normal-sized thyroid should alert the physician to the possiblity of some other cause of the illness.

The consistency of diffuse toxic glands is firm but elastic, or very firm if iodide has been given. The borders are easily demarcated by palpation. The pyramidal lobe should always be searched for since enlargement indicates the presence of diffuse disease of the thyroid. Also, if left behind at operation, it may be the site of recurrence of the disease.

Thrills and bruits are important but often absent. Their presence usually denotes hyperfunction. A thrill is less common than a bruit. It is more likely to be felt as a systolic purr in the region of the superior poles over the superior thyroid arteries. Bruits may be continuous or systolic in time, similar to a blowing cardiac murmur. Usually they are audible over the entire thyroid, often being louder on one side than on the other. Either a thrill or a bruit is highly suggestive, but not pathognomonic, of thyrotoxicosis. If local examination of a goiter discloses either of these signs, even though other evidence of hyperfunction may be lacking, especially careful investigation into the possibility of thyrotoxicosis is indicated. Both thrills and bruits tend to decrease in intensity as thyrotoxicosis subsides. They completely disappear in a few days under treatment with iodide.

The thrill is the palpable and the bruit the audible sign of turbulence associated with an increased rate of flow through rather tortuous vessels. The location of the thrill suggests that the larger thyroid vessels are chiefly responsible. Bruits may be distinguished from venous hums by occlusion of venous return caused by gentle pressure above the thyroid. A carotid or innominate thrill or bruit may be difficult to distinguish from sounds originating in the thyroid gland. Their localization over the vessel and distal transmission usually allow a distinction to be made.

Neighborhood symptoms, including dysphagia and the sensation of a lump in the neck, may be produced by toxic as well as nontoxic varieties of goiter. Sometimes the supraclavicular lymph nodes become enlarged and tender. ¹⁶⁴

Vocal cord palsy is encountered, but is found chiefly in cancer of the thyroid, occasionally in nodular goiter, and only rarely in Graves' disease. Occasionally it is found on routine preoperative laryngoscopic examination, having produced no symptoms such as dysphonia or hoarseness.

The Skin

Cutaneous manifestations are nearly always present when hypermetabolism is significant. The patient feels hot and prefers a cold environment. Active sweating occurs under circumstances that would provoke no response in normal persons. Hand shaking gives a nearly diagnostic impression. The hand of the thyrotoxic person is erythematous, hot, and moist (sometimes actually dripping wet), in a state of hot hyperhydrosis. Although such hands may occasionally be found in other conditions, the finding of a cold hand, dry or moist -- almost excludes hyperfunction of the thyroid. Flushing is also very common, more in younger patients than in older ones. There may be more or less continuous erythema of the face and neck, with superimposed transient blushing. Occasionally diffuse pruritis or urticaria occurs. Urticaria appears to be linked to Graves hyperthyriodisim by some mechanism, but  so far the causal relation  is unknown(164.1).

The vasomotor system is overactive. Many of these cutaneous manifestations may be considered expressions of or incidental to increased heat elimination.

Redness of the elbows, first noted by Plummer, is frequently present. It is probably the result of the combination of increased activity, an exposed part, and a hyperirritable vasomotor system.

Although the integument is thinned, manifestations due to alteration in the growth of the tissue are less evident. It is possible that the type of fingernail described by Plummer (onycholysis) belongs in this category (Figure 10-7). The process may involve all fingers and toes, but typically begins on the fourth digit of each hand. The free margin of the nail leaves the nail bed, producing a concave or wavy margin at the line of contact. The hyponychium may be ragged and dirty, despite the best efforts at personal hygiene. Plummer's nails are a frequent and interesting clinical finding in Graves' disease. Occasionally the spoon-shaped fingernails of hypochromic anemia are encountered.

Fig. 10-7. Plummer's nail changes, showing thinning of the nail and marked posterior erosion of the hyponychium.

Patchy hyperpigmentation, especially of the face and neck, is frequently seen, and occasionally there is a general increase in pigmentation. Most dark-skinned persons detect a definite increase in pigmentation during the onset of thyrotoxicosis, which may be dramatically localized around the eyes.

Patchy vitiligo is found in 7% of patients with Graves' disease, and we have observed several instances of complete loss of pigmentation in association with thyrotoxicosis. These changes are manifestations of associated autoimmunity directed toward melanocytes. The vitiligo, often of the hands and feet, may precede the onset of Graves' disease by years or even decades. Observation of this change is a useful clinical sign when attempting to establish the cause of thyrotoxicosis or exophthalmos.

Hair tends to be fine, soft, and straight. Women may complain that it will not retain a curl. (This complaint is also typical of patients with myxedema.) Temporary thinning of the hair is common, but alopecia is rare. Hair loss is often extreme after marked changes in metabolic rate are induced during therapy. We have seen complete or partial alopecia develop in a few patients with Graves' disease, sometimes in association with urticaria. These changes are believed to be manifestations of autoimmunity directed against the hair follicles.

Peripheral edema, unrelated to congestive heart failure or renal disease, is very common.

Pretibial myxedema (Figure 10-8) and the other remarkable abnormalities of "thyroid acropachy" are discussed in Chapter 12.