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Date of last update: 10/17/2017.

Forum Name: Endocrinology Topics

Question: High Free T4 Norma TSH

 baschez - Sun Apr 19, 2009 12:46 am

I recently saw a cardiologist because I found that my QTc interval was prolonged. I ended up getting a echo test and he diagnosed me with pulmonary hypertension. I've done research and seen that a prolonged QTc and pulmonary hypertension can be related to hyperthyroidism and asked him to order labs. I got my labs back and my FT4 was 1.8 (Lab normal is .8-1.6) and my TSH was 1.590 (.4-4.5).

I know that diagnosis of hyperthyroidism is usually involves low TSH values, but mine seem to be normal, but I can't seem to find a reason that my FT4 was high. The cardiologist seemed to think it wasn't a big deal and still can't find a reason that I would have pulmonary hypertension.

I'm in decent shape (>1300kcal/week cardio). I have had heat and light sensitivity since I was very young. I'm susceptible to heat exhaustion. My heart rate is usually in the 80's, and I tend to have higher blood pressure, but it is normal sometimes. I'm also dyslexic.

Should I see an endocrinologist, and could I have thyroid malfunction?
 John Kenyon, CNA - Wed Apr 29, 2009 1:19 pm

User avatar Hi there --

The conncections between hyperthyroid and both long Q-T and pumonary hypertension (or cor pulomale -- CP) are tenuous at best. And while your Free T4 was outside the high end of normal, it was only a very slight evevation. This should be repeated, perhaps more than once, to determine just what's going on if anything, but it is likely a trivial finding as your cardiologist has said. Still, it is only reasonable to be sure of that.

On the other hand long Q-T and CP are not trivial findings and warrant close followup and possible medical therapy as well. I trust the doctor is doing this.

I don't think you likely have a hyper thyroid condtion, but only followup tests can make this certain. Even if you do, again, the connection between profound hyperthyroid and the other conditions is tenuous. What your test showed would not account for either and, again, these do need to be closely followed.

I hope this is helpful to you. Good luck with this and please follow up with us as needed.
 baschez - Sat May 02, 2009 6:21 pm

Thank you for your help, but it seems that I'm about in the same situation.

I don't believe that the link is tenuous. A study done by U GUNTEKIN, M.D et. al. showed that out of 16 people with hyperthyroidism and long QT, 10 of them no longer had pulmonary hypertension or a long QTc after treatment. Also, I don't understand why it would matter if my TSH is normal or not. 2% or hyperthyroid cases don't have an subnormal TSH, and it has to do with the hypothalamus being insensitive to T3 or another cause that I don't remember. My wife who has been diagnosed hyperthyroid, had the exact same T4 value before treatment, and since T4 and T3 are what cause a person's metabolic rate to increase, not TSH, I don't understand why having a normal TSH would even matter.

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