This state, termed “subclinical hypothyroidism,” is most commonly an early stage of hypothyroidism.
Although the condition may resolve or remain unchanged, within a few years in some patients, overt hypothyroidism develops, with low free T levels as well as a raised TSH level.
Pituitary failure is a cause of secondary hypothyroidism but since, in this circumstance, the TSH level is low rather than high (and thus the direct cause of the thyroid failure), this condition cannot be diagnosed with certainty until thyroid hormone levels fall below normal, and subclinical hypothyroidism as usually defined would not be detected.
The elevation of TSH levels reflects the sensitivity of the hypothalamic-pituitary axis to small decreases in circulating thyroid hormone; as the thyroid gland fails, the TSH level may rise above the upper limit of normal when the free T level of 6 or 7 μg per d L (77 to 90 nmol per L), although not outside the normal range of 4.5 to 12.5 μg per d L (58 to 160 nmol per L), may represent a significant fall from an original level of 9 or 10 μg per d L (116 to 129 nmol per L) and, thus, is low for this particular patient..
Chief among these is chronic autoimmune thyroiditis (Hashimoto's disease), which is commonly associated with increased titers of antithyroid antibodies, such as antithyroid microsomal antibodies (antithyroid peroxidase) and antithyroglobulin antibodies.5 This disorder is suspected when thyroid enlargement is observed, but antithyroid antibodies may also be associated with atrophy of the thyroid and hypothyroidism.
In short, it seems reasonable to treat patients who have a TSH level that is consistently elevated above 10 μU per m L (10 m U per L), especially if titers of antithyroid antibodies are increased.
Also, patients who complain of fatigue, dry skin, constipation, muscle cramps or other common symptoms of hypothyroidism may possibly benefit from treatment even if their TSH level is elevated only into the 5 to 10 μU per m L (5 to 10 m U per L) range.
An algorithm summarizing this approach is presented in has a short half-life and requires multiple daily doses to maintain blood levels in the normal range.
Levothyroxine, however, has a long half-life (approximately seven days) and is partially converted to T with a single daily dose.15In patients with overt hypothyroidism, the average daily replacement dosage of levothyroxine is 75 to 125 μg, or 50 to 100 μg in the elderly, or about 1.6 μg per kg per day.In patients with subclinical hypothyroidism, not surprisingly, the same changes are present but are less marked and less consistent.This pattern of lipid abnormalities, of course, is important because it is a risk factor for atherosclerotic cardiovascular disease.Dry skin, cold intolerance and easy fatigability were significantly more common in the patients with raised TSH levels, and these symptoms improved after treatment with thyroid hormone.In another study11 of 69 female patients with subclinical hypothyroidism, a clinical index based on symptoms and physical signs was shown to be more abnormal in patients with higher TSH levels, even though all patients had normal serum levels of TIn patients with full-blown hypothyroidism, serum levels of triglycerides, total cholesterol and low-density lipoprotein (LDL) cholesterol are elevated.Another common cause of hypothyroidism is the treatment of Graves' disease.Tags: Adult Dating, affair dating, sex dating