Screening for Hypothyroidism

Thyroid disease is very common. There is ongoing debate as to whether we should screen everybody, or just wait until people complain of symptoms before we do thyroid blood tests. And then, which blood tests should we do?

A recent study from the Netherlands published online in Clinical Endocrinology adds weight to the argument for not just waiting for patients to complain of symptoms. The authors found that symptoms of hypothyroidism in pregnancy were an unreliable guide as to whether the patient was hypothyroid or not. It is important in pregnancy as the presence of an under-active thyroid can affect the outcome of pregnancy - both for the mother and for her baby.

Whether during pregnancy or not, the symptoms of an under-active thyroid are non-specific and vary greatly from one person to another. Thyroid disease affects one in 20 of the population - more if you are older, especially if you are female. If you wait until typical hypothyroid symptoms develop, there may be a preceding prolonged spell of relatively poor health, and it may be all the harder to get back on track.

If we do not screen everybody for thyroid disease (and current guidelines suggest we do not), then we should at least have a low threshold for ordering thyroid tests.  At present, TSH alone is recommended as the initial screening test. However, cases of subclinical thyroid disease will be missed if thyroid hormone and antibody tests are not requested. The antibody tests are important as they will identify individuals at risk of hypothyroidism or hyperthyroidism, even if they do not currently have symptoms.

 

 

Do normal thyroid tests mean that your thyroid is in good balance?

   Not necessarily according to a new study just published (see www.gordianhealth.com.au). Patients using L-thyroxine who had a normal TSH, were more heavier and more likely to be taking medications for depression, to lower blood pressure and to lower cholesterol.  

Do we give too many people thyroxine?

  No question, if your thyroid is really underactive you need thyroid hormone replacement. However an article just published online in the Journal of the American Medical Association (JAMA) Internal Medicine suggests that too many people, particularly older people, are given thyroid hormone.
The article cites the case of a 72-year-old man who was started on thyroxine, and soon after attended ED with palpitations, shortness of breath, and chest pain. He had a common heart rhythm disturbance called atrial fibrillation.
  Here's the problem in a nutshell: Underactive thyroid is common, affecting around 3% of the population. Hypothyroidism should be treated. However, many more people have what is called "subclinical hypothyroidism". Here, thyroid hormones are in the normal range, but the hormone TSH is increased. Thyroid symptoms do not correlate real well with thyroid hormone measurements, particularly when the abnormality is mild. Increased TSH (a hormone produced in the pituitary) is a sign that the body is trying to drive the thyroid gland to produce more thyroid hormones.
  Subclinical hypothyroidism affects between 4 and 12% of the population. This may be up to 20 million people in the United States and up to one billion people worldwide. Thyroxine is the most prescribed medication in the United States.
  Are we giving too many people thyroid replacement? The JAMA article reminds us that thyroid hormone replacement has risks, as well as potential benefits. However, the symptoms from an underactive thyroid affect people differently.  Some people get symptoms when the thyroid under activity is only mild or subclinical.