Still Exhausted? Treatment of Subclinical Hypothyroidism

My doctor said all my labs look normal and to keep her updated if I start feeling worse. Should I see a new doctor?

I get a version of this every week. The answer has two halves. The labs are almost certainly right. And the symptoms are almost certainly real. Both of those things can be true at once, and once you accept that, the next step becomes obvious. The same logic decides the question I get asked most, which is whether treatment of subclinical hypothyroidism, a mildly raised TSH with no symptoms, is ever the right call.

Key takeaways

A normal TSH can be trusted. The TSH and free T4 assays are precise to multiple decimal points; the one exception is if the patient is using a lot of biotin, which can distort the result.
A normal TSH runs from about 0.5 to about 5 at most laboratories. Between about 5 and 10 is the “gray zone.”
Subclinical hypothyroidism, a gray zone TSH with no symptoms, is usually just watched, because giving thyroid hormone to someone who does not need it can impair muscle mass, reduce bone mass and cause arrhythmias.
A gray zone TSH with symptoms (cold, tired, low) is treated with a small dose of thyroid hormone, and then we watch to see whether the symptoms improved.
When labs are entirely normal and exhaustion persists, sleep quality and nutrition account for most cases, and neither shows up on a thyroid panel.

Can you trust a normal TSH?

Yes, a normal TSH can be trusted. The TSH and free T4 assays are precise to multiple decimal points. TSH in particular, which your pituitary makes in response to how much thyroid hormone it is sensing, is exquisitely sensitive to the whole conversation about thyroid demand. If it is normal, we can be very confident that it is true.

The one exception is biotin. If you take a lot of biotin, the assay can give results that do not make sense. If you are not, there is nothing to worry about on that front.

So when the thyroid labs are normal and the symptoms persist, the thyroid is not an excuse to stop thinking. It is the reason to start thinking about everything else.

If this is the question you came in with, it is the one we answer in your first hour here. New patients are seen within two weeks and you do not need a referral. Call or text (817) 380-4880.

Why do I feel hypothyroid when my labs are normal?

Because the symptoms we associate with hypothyroidism are non specific. Fatigue, weight gain, feeling cold, low mood, mood swings. Every one of them has other causes, and not all of those causes are endocrine.

Consider anemia. Maybe you feel tired, short of breath, cold, low. You think you are anemic. We run the test and there is zero evidence of anemia. We do not say, “You must still have anemia even though we cannot see it.” That is not real. Anemia leaves the conversation, and we look for the actual reason. The thyroid works the same way. The poor thyroid gets blamed for everybody’s problems when it is back there quietly keeping your thermostat right.

That does not mean you stop paying attention to the symptoms. It means the cause is probably not endocrine, and it deserves exactly as much attention as if it were.

My TSH is 4.65 and my doctor will not treat me. Is that right?

It depends on how you feel, and on the trend. Different laboratories use slightly different ranges, but as a general principle a normal TSH runs from about 0.5 to about 5. Some labs cap it at 4.5, some at 4.8. A TSH of 4.65 sits at the top of that range.

A TSH at the top of the range means your pituitary is asking for a little more hormone. If your thyroid delivers, the number settles. If TSH has been creeping up over time, that trend matters and we watch it.

Between about 5 and 10 is the gray zone. If you are in the gray zone and you have symptoms, (you feel cold, tired, depressed, sleepy) we treat. We give a small amount of thyroid hormone and see whether you feel better. Not everyone does, and that itself is information. If you have a strong family history of hypothyroidism, we watch more closely, because these things cluster in families, especially with age, and it may be a smoldering Hashimoto’s thyroiditis beginning to have a real effect.

Why do labs disagree about the normal TSH range?

Because each laboratory sets its own reference range, based on the population it serves and the accuracy of the assay it uses, and recalibrates it over time. There is some evidence that ethnicities and age groups differ, and that in someone in their eighth decade a TSH of 5 or 6 may still be considered normal.

Someone wrote that everything online says 0.4 to 4.5 is normal but their doctor’s lab says anything under 6 is normal. I have not personally seen a reference range that goes to 6. Six as a general upper limit is unusual. It may be worth having the test run at a different laboratory and seeing where you fall in their range. What matters most is how you feel.

I have been on the same dose for ten years with a normal TSH and I still feel terrible. Why?

Your doctor is not wrong that the biochemistry is normal. That means your thyroid function has been optimized and the normal conversation your body needs has been restored. When someone is biochemically normal and symptoms persist, I come back to the same principle. Something else is producing these symptoms, and we have to find it.

There is also a question of proportion. If the thyroid change was subtle and the symptoms are extreme, we are out of proportion, and we cannot pin all of that on one small shift in one hormone. That applies whether you have Hashimoto’s or no thyroid at all after a thyroidectomy.

Normal TSH and still exhausted: what else is worth checking?

Sleep, first. The most common thing I see behind persistent exhaustion is sleep. Even if you are getting eight hours, if it is not restorative sleep, forget it. All bets are off. It does not matter how good your labs look, you will feel terrible. Nutrition, second: enough protein, and any vitamin deficiency.

Then the rarer things: a rheumatologic problem, a metabolic one, another sleep disorder. But sleep and nutrition account for most of it, and neither shows up on a thyroid panel. That workup is the conversation to have with your doctor, or with an endocrinologist if you want a second set of eyes.

When is treatment of subclinical hypothyroidism the right call?

Usually it is not, and the general wisdom is to watch. Subclinical means no symptoms. You feel fine. Hypothyroidism means the TSH has started to rise because the pituitary is asking for more. So subclinical hypothyroidism is a mildly raised TSH, in the gray zone between about 4.5 and 10, in someone who feels well.

The reason not to treat is that giving thyroid hormone to someone who does not need it, especially when the change may resolve on its own, causes harm. It can impair muscle mass, reduce bone mass, and cause arrhythmias. You do not need that.

The opposite case is different. A subtly raised TSH with real symptoms, cold, tired, low, is treated with a small dose to restore the normal biochemistry, and then we ask whether the symptoms improved.

Does Hashimoto’s start with a high TSH and normal T4 and T3?

Often, yes, and the TSH is the number to trust. The free T3 assay is not very reliable. TSH starts the conversation. It senses the proportion of T4 and T3 coming back and adjusts. If TSH is high while free T4 is normal, we know the body is not getting enough, whatever the T3 assay says. TSH is in charge.

The free T3 assay is improving, but we do not lean on it. Not all low T3 is a problem. Your need for thyroid hormone changes with what your body is doing. An ultramarathon runner or a pregnant woman needs more, and the thyroid ramps up. Someone in intensive care, after surgery or trauma, needs less, because the brain puts the thyroid on the back burner until the crisis passes. One isolated, mildly high TSH is not the end of the story. A lot of these resolve on their own. Check again later.

What do TPO antibodies show that TSH does not?

TPO antibodies tell you the mechanism. A positive TPO means you have Hashimoto’s thyroiditis, an autoimmune process that gradually destroys thyroid function. TSH tells you where the function is today. TPO tells you why it is moving and that it will probably keep moving.

They are very common. Somewhere between 30 and 40 percent of the American population carries TPO antibodies, many without knowing. A positive result does not mean treatment. It means we know what we are watching.

Where this leaves you

Believe the TSH. It is one of the most precise tests in the laboratory catalog. Then keep looking, because the symptoms are real and the cause is probably sleep, nutrition, or something else that never shows on a thyroid panel. In the gray zone with symptoms, we try a small dose and see. Without symptoms, we watch, because treating a thyroid that does not need it costs muscle, bone and rhythm.

See your own numbers, not a guess. Normal labs and still exhausted is a diagnosis still to be made, not a door to be closed. Bring the labs and the symptoms together. A new consultation is an hour, $400, includes the first follow up, and can be done by video in seven states. To book your consultation, call or text (817) 380-4880.

Frequently asked questions

Why am I still tired when my thyroid labs are normal?

Because the cause is probably not your thyroid. TSH is a highly precise test, and a normal result can be trusted. Sleep quality and nutrition are the two most common reasons for persistent exhaustion with normal labs.

Is a TSH of 4.65 normal?

Borderline. It sits at the upper edge of most reference ranges and inside the 4.5 to 10 gray zone. With symptoms, a trial of treatment is reasonable. Without symptoms, it is watched, especially if the trend is rising or there is a family history.

Does treatment of subclinical hypothyroidism help if I have no symptoms?

Usually not. With no symptoms and a TSH under 10, treatment risks muscle loss, bone loss and arrhythmia for no benefit, and the change may resolve on its own. Symptoms change the answer.

Why do different labs have different TSH ranges?

Each laboratory sets and recalibrates its own range based on its population and its assay. A range extending to 6 is unusual. Testing at a second laboratory is a reasonable step.

What is the most reliable thyroid test?

TSH. It starts the hormonal conversation and responds to both T4 and T3. TSH and free T4 are precise to multiple decimal points, so a normal result can be trusted. Free T3 is the least reliable assay and is not used to drive decisions.

What does a positive TPO antibody mean?

Hashimoto’s thyroiditis, an autoimmune process that slowly reduces thyroid function. It explains the trend in TSH but does not by itself require treatment. TPO antibodies are common, and a positive result tells us what we are watching rather than what to treat.

Normal TSH but Still Exhausted? When Subclinical Hypothyroidism Needs Treatment