Common Symptoms Could Mask Hypothyroidism


SAN DIEGO — Symptoms of hypothyroidism such as fatigue, depression, myalgias, cold intolerance, and menstrual abnormalities can be so common that they often blur the distinction between screening and case finding.

“Such symptoms are commonly seen in primary care, so you have to have a low threshold to find hypothyroidism,” Dr. William A. Norcross said at the annual meeting of the American Academy of Family Physicians. He discussed other symptoms of hypothyroidism that can be easily overlooked:

Hyperlipidemia. Lipid abnormalities are dependent on the degree of thyroid failure and are more pronounced in patients with thyroid-stimulating hormone levels above 10 mU/L. “So if you're screening a patient for hypercholesterolemia and you detect it, you should give some consideration to checking a TSH because replacement therapy not only will help the patient feel better, but will help the elevated LDL situation,” said Dr. Norcross of the department of family medicine at the University of California, San Diego.

Hyponatremia. “There is a relationship between hypothyroidism and hyponatremia, especially in elderly patients,” he said. “It's important to detect because the hyponatremia can be difficult to treat if you're missing the underlying cause.”

Myalgias/myositis. One of Dr. Norcross's patients, a healthy-looking middle-aged man, presented with severe myalgias and a TSH level of 150 mU/L. “Every muscle in his body ached,” he recalled. “You couldn't duplicate it with palpation. It was very vexing. Hypothyroidism turned out to be the cause of this muscle pain, and his symptoms went away with levothyroxine replacement.”

Such a case “is not an everyday occurrence, but it happens and is important to keep in mind,” said Dr. Norcross, who also directs the physician assessment and clinical education program at the university.

He also noted that certain drugs may affect thyroid function and thyroid test results. These include lithium, drugs that decrease TSH secretion (such as dopa-mine, glucocorticoids, and phenytoin), and drugs that increase TSH secretion (such as metoclopramide, domperidone, and amiodarone).

According to the United States National Health and Nutrition Examination Survey III, the overall incidence of hypothyroidism in the United States is 4.6%. It's eight times more common in women, compared with men.

Dr. Norcross said that he had no conflicts to disclose.

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