Bone mineral density in premenopausal women receiving long-term physiological doses of levothyroxine

Article Abstract:

An overactive thyroid (hyperthyroidism) can cause the loss of bone mass, and is one of the major risk factors for the disease osteoporosis (involving weakening and fractures of the bones) among women. Bone loss is also caused by excessive doses of thyroid hormone; it has been reported that adverse changes in bone structure occur among patients given levothyroxine sodium replacement therapy for hypothyroidism (underactive thyroid). Thyroid hormones are among the most frequently prescribed drugs, but the long-term effects of thyroid hormone replacement therapy on osteoporosis are not known. Among postmenopausal women, the effects of this therapy are difficult to measure because lack of estrogen also affects bone mass. In addition, hormonal changes after removal of the thyroid may contribute to bone loss. Twenty-six premenopausal women being treated with thyroid hormone therapy (levothyroxine sodium) for Hashimoto's thyroiditis (a form of hypothyroidism) were compared with a group of 94 normal controls. The women receiving levothyroxine showed decreases in density in the bones of the hip, pelvis, and arms. The type of bone loss was similar to that caused by hyperthyroidism, even though the dosage never caused their thyroid hormone levels to rise above normal. It is not known why patients with hypothyroidism who are given replacement therapy develop bone loss. If it is caused during the initiation of treatment, the amount of levothyroxine given at the beginning should be kept to a minimum and increased slowly. Despite a free thyroxine index (FTI) in the normal range, patients with higher FTI levels still suffered bone loss. The levothyroxine dose should be kept at the minimum required, and patients should be carefully monitored during treatment. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Bones, Women, Risk factors, Women's health, Osteoporosis

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Pseudomalabsorption of levothyroxine

Article Abstract:

Levothyroxine sodium is the most common therapy for hypothyroidism (underactive thyroid gland). Occasionally patients continue to show symptoms of hypothyroidism in spite of treatment, suggesting resistance to thyroid hormone or the existence of pituitary tumors. However, when there is chemical evidence that thyroxine levels are low, the patient may not be taking the medication as directed. If it appears that the patient is taking levothyroxine correctly, other factors affecting absorption may be causing the problem. Four patients with symptoms and test results indicating hypothyroidism while under treatment with levothyroxine were examined and found to have normal absorption of the drug. The four cases are discussed in detail. All four patients exhibited signs of factitious illness, and probably suffered from Munchausen syndrome (insistence on illness in spite of all evidence to the contrary, falsification of symptoms, use of aliases and frequent changing of doctors). Because these cases were caused by noncompliance with therapy with the intent to deceive, the disorder was named pseudomalabsorption of levothyroxine. The incidence of this disorder is unknown, and cases are probably rare. Systemic illness and drug interactions must be ruled out before malabsorption is attributed to psychopathological causes. (Consumer Summary produced by Reliance Medical Information, Inc.)

Case studies, Evaluation, Factitious disorder, Factitious disorders

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Addisonian crisis as presenting feature in malignancies

Article Abstract:

The adrenal glands are frequent locations of metastatic tumors, those which have spread from their primary site. This is due to both the rich blood supply of the adrenals and the presence of implantation-promoting steroid hormones. Despite the frequency of metastatic tumors taking up adrenal residence, few patients complain of symptoms of adrenal insufficiency. The function of the adrenals is sufficiently robust that over 90 percent of the tissue must be affected before actual clinical symptoms can be observed. Two patients were seen, however, with symptoms of Addison's disease found to be due to metastatic tumors. Addison's disease is caused by a deficiency in the secretion of adrenocortical hormones, and is characterized by patchy skin, black freckles, fatigue, nausea and other symptoms. It is important to note that tumor metastases may appear in both adrenal glands before the original tumor can be localized, and, even if the tumor is not amenable to aggressive intervention, patients in such cases may be kept well for a long time. Steroid replacement therapy prevents acute complications due to Addisonian crises and can provide improved quality of life and increased survival time. (Consumer Summary produced by Reliance Medical Information, Inc.)

Cancer, Addison's disease, Endocrine gland cancer

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