Underactive Thyroid Misdiagnosis Can Cause Problems For Elderly Patients: Study

A case study suggests that elderly individuals often receive a misdiagnosis that they suffer from an underactive thyroid, resulting in the unnecessary prescription of thyroid hormones. 

Doctors from the Mayo Clinic in Rochester, Minnesota and University Hospital in Monterrey, Mexico published a case study earlier this month in the medical journal JAMA Internal Medicine, in the “Teachable Moment” section, warning that elderly patients with subclinical hypothyroidism may be misdiagnosed with clinical hypothyroidism.

According to the authors, a 72-year-old man was diagnosed with hypothyroidism after complaining of fatigue and prescribed a blood thyroid-stimulating hormone (TSH), resulting in heart palpitations, labored breathing and chest pain. The stud determined that he had been wrongly diagnosed with clinical hypothyroidism when he only had subclinical hypothyroidism.

Elevated levels of TSH are seen as an indication that the thyroid is making too little of necessary thyroid hormones. TSH therapy with levothyroxine, sold under the brand names of Synthroid and Novothyrox, is used to cause the thyroid to increase metabolism hormone production.

A healthy TSH level is considered between 0.3 and 5.0 microunits per millimeter. However, the patient had levels of 7.2 microunits per millimeter, which doctors took as an indication of hypothyroidism.

But the authors of the study cautioned that about 15% of people have subclinical hypothyroidism, which causes few to no symptoms, and elderly patients may have a higher range of TSH levels in their blood than other adults and still be subclinical. Treating them with Synthroid or Novothyrox can result in health problems like those suffered by the case study patient, they warned.

The patient was taken off the drugs after tests revealed they had driven his TSH levels down to 0.1 microunits per millimeter and after a few months his levels returned to 5.6, which are considered slightly high for most adults but may be in the normal range for the elderly.

Researchers recommended that fatigue should not be taken as an immediate sign of hypothyroidism, and instead suggested testing TSH levels more than once in a three to six month period may more accurately determine whether a patient needs treatment, and prevent a misdiagnosis.