Monthly Archives: March 2009

Dr. Cobbs Clarifies His Position on Thyroid Hormone Replacement

Dr. Cobbs responds to questions from Tony Kingkade, regarding the use of branded t4 (Synthroid), in the treatment of hypothyroidism. Dr. Cobbs, Chief of Endocrinology at North General Medical Center, writes:

Mr Kingkade has a very interesting opinion. I prefer to deal with the facts. First, the AACE position was posted after not before the FDA approved other brands of levothyroxine. Second, the FDA has stated that they do not use TSH to assess equivalence of levothyroxine preparations. They use area under the curve concentration which is not as accurate. Endocrinologists use a sensitive TSH assay which is more precise.

There is no myth if you read the literature. Since so many people misunderstand the facts, a joint position paper was published on the internet.
AACE, The Endocrine Society and the American Thyroid Association published the joint statement. The statement was published after the FDA refused to listen to the opinions of all three groups of endocrinologists. The joint statement is the one that states that branded levothyroxine should be used instead of generics. And it was issued in 2004

Also for the record, the FDA allows for significant variance from the stated dosage. Some generics are more “bioavailable” and others are less available resulting in differing thyroid function test results despite all claiming to be the exact same strength using FDA standards. Differing manufacturing techniques account for the differences.

As for the Boots paper, Boots was wrong in withholding their paper however a careful review of the other published literature reveals many other papers that demonstate differences in blood levels of different brands even when the dosage claims to be the same.

For the record, I am not a paid speaker for any pharmaceutical company. I have taught and continue to teach endocrinology to residents, attending physicians and medical students for more than 20 years. I prefer to deal with facts as represented in the published literature. A drug company paid speaker gives a promotional lecture. Don’t expect facts from them.

The facts stand for themselves. The recommendation to use branded levothyroxine is that of AACE, The Endocrine Society and the American Thyroid Association. I stand by the recommendation of all three associations of endocrinologists. The facts speak for themselves.

Kelly Offers Advice to Help Those with High Metabolism

Kelly offers this advice to our members like Amanda who have been unable to keep their weight up.

Thanks Kelly for offering your thoughts.

Kelly writes:

Ladies, while you each are blessed by the fact that you do not have an obesity problem, your problem is no less real to you. I recommend calling around in your area (universities, or bariatric physician) and see if a professional can test your resting metabolic rate. If this is not a possibility, get with a registered dietitian or an exercise physioligist that has experience with weight management, so they can estimate your metabolic rate. Next, based on your activity level they can estimate the number of calories you use up in a day (resting metabolic rate, activities of daily living, and exercise). This will give you the estimated number of calories that you use up in a day. Wtih this number, you add 500 to 1000 extra calories per day and you will gain 1-2 pounds per week. It is best to add weight training with this routine so most of the extra weight is in muscle and not too much fat. You will get some of both though. You should get good dietary counsel so you do not get too many calories from unhealthy sources. Also, you do not want to develop bad eating habits. Eventually with your weight gain and added muscle mass, your metabolic rate will increase and your weight gain will stop and you will be at a new, healthy, higher weight. Good luck.

Tony Kingkade Responds to Dr. Cobbs

Several days ago, Dr. Ron Cobbs offered his opinion on thyroid hormone replacement therapy. He was very much in favor of using pure t4 therapy, specifically the branded products (Synthroid, Levoxyl). Now Tony Kingkade offers his response to Dr. Cobbs. Read his opinion below:

Mr Kingkade writes:

C’mon Dr. Cobbs…just stop it!

Dr. Cobbs perpetuates the myth that “branded” levothyroxine products (I assume he means Synthroid or Levothroid) are preferable to other manufacturer’s products because the AACE says so. First of all, the AACE statement was published many years ago before ANY levothyroxine product had undergone the FDA approval process. Since then, ALL levothyroxine products on the market today have undergone the same, exact FDA approval process. Some have also demonstrated AB bioequivalency to other “branded” products…ie Mylan levothyroxine is bioequivalent to Synthroid. The generic companies have manufacturing technology, consistency in product and batch-to-batch bioequivalency that rivals or exceeds any branded manufacturer. They know that there can be no variation in their product and they make that a priority.

That this”brand is better” myth continues today is appalling. It was originally promoted by Boots (former Flint and manufacture of Synthroid) and only exposed as false when Boots commissioned a study at UCSF to compare their product to various generic levothyroxine products. When the results of the study showed no difference in blood levels, Boots withheld publishing of the study. A Wall Street Journal article exposed this and the lawsuits from health plans (that paid more for Synthroid than equivalent generics) extracted millions from Boots.

In fact, at one CE presentation, I asked the Boots paid speaker why I should change my generic stabilized patient over to Synthroid since, according to him, there might be huge negative effect if one changes between Synthroid and a generic. He was unable to answer the question (because, to be consistant, it would mean that one should never convert back to Synthroid if already stabilized on another product.)

I know about low therapeutic indexes and the FDA allowable variation in potency for products. I get it! But all these manufacturers get it too. They make sure their drugs are right on, every batch, assay to assay.

So I ask you, Dr. Cobbs, to show us unequivicable proof that this isn’t true. In fact, just show us that the branded products have less variation in their batch-to batch assays than the generics. Give us the proof!

I’m not associated with any generic drug manufacturer. In fact, my wife is employed in a high science position by a major US/worldwide brand name manufacturer. So, if anything, I’m definately pro brand-name. But Dr. Cobb’s support of the AACE recommendations to use only branded versions of levothyroxine is just plain wrong.

From More Attacks on Use of Armour Thyroid, 2009/03/23 at 11:26 PM

Dr. Ron Cobbs, Noted Endocrinologist, Speaks Out

We welcome a contribution from Dr. Ron Cobbs.

Dr. Ron Cobbs and I go way back. We knew eachother when he was finishing his endocrinology fellowship at LIJ Medical Center on Long Island in the 80’s. Later he worked as an attending Endocrinologist at a New York City Hospital when I was the Director of an endocrine training program in another part of the city.

Ron leaves his opinion (below) for us to ponder on the subject of thyroid hormone replacement therapy. I guess Ron and I will just have to disagree about the use of Armour thyroid but we both recognize the value of adding t3 (Cytomel) to traditional pure t4 (Synthroid) therapy in selected individuals who need more complex replacement therapy to achieve a good clinical response.

Thanks Ron for your comments!


Dr. Cobbs writes:

Several points should be noted. The American Assciation of Clinical Endocrinologists (AACE) recommends against the use of dessicated thyroid preparations. They specifically recommend levothyroxine and preferably branded versions as small changes in concentration have marked differences in clinical effects and blood test results such as TSH and free T4. Further, the endocrine literature reports that although most patients are successfully treated with branded levothyroxine alone, there is a small minority who never feel back to normal. However the literature supports the addition of T3 in the form of Cytomel rather than to retreat to the non-precise dessicated thyroid preparations of the past.

An experienced endocrinologist familiar with the literature can by precribing branded levothyroxine be able to treat most of their hypothyroid patients to the satisfaction of both phyician and patient. However the endocrinologist must listen to their patients and follow thyroid function blood tests. Even when the blood tests are normal, if the patient still does not feel normal again, the careful addition of amounts of T3 (cytomel) to the thyroxine will usually help the rest to feel better again.

Also remember to avoid taking iron replacement and medications such as cholestyramine or colesevelam too close to the levothyroxine as they prevent the adequate absortion of levothyroxine in the body.

Carol’s Experience with Thyroid Hormone Replacement.

Carol has submitted a great post about her experience with thyroid hormone replacement therapy. I think our visitors will find it helpful.

You can find her post on our forum page at:

Click on over to the forum and browse for a minute. Chances are you will find it a great source of information.


Gary Pepper, M.D.

Lil mamii joins the high metabolism club

It is really startling how many people suffer from being underweight, and how much these people suffer from that. We focus so much more on the more common problem of being overweight, but there is something for us to learn from the opposite problem. Maybe someday we can unravel the metabolic tricks that make for these wide differences so we can help both sides of this issue.

Here is Lil Mamii’s story:

Im 18 goin on 19 iv neva weighd ovr 116 pounds..iv ben lil all ma 5′6..i eat so much dat erybody calls me i dnt gain n e weight..i weigh bout 106..i nw understand i cant eryting i want cause ppl wit high metablism r at risk 4 high ima use da tips i hopefully i gain sum tird of feelin an lukn unhealthy..

Shima Shares Metabolic Profile with Amanda

Hi Amanda. I’m 5′1″ and 97 lbs. Some days I love how I look but some days I think that I’m just too skinny. Some of my friends would tell me how skinny I am and it used to make me feel really bad. I always kept quiet and never said anything bad. Then some time ago I thought I won’t let it get to me anymore. I mean, some days I still hate how I look but there’s nothing I can change about it. I eat a lot but I just don’t gain weight.
So now whenever a friend told me how skinny I am, I’d just say ‘So? It beats trying to get thin and failing’. You see, the friends who’s been calling me skinny are actually the ones who are on diet, and one is even skinnier than I am!