RLC Labs issues Nature-Throid and WP-thyroid recall for subpotency

Oh my. Now another American desiccated thyroid (NDT) brand recall?

Earlier this year, Acella’s NP thyroid was found to be superpotent (over 110% on the T3 content), and they issued a voluntary recall.

Now, as of August 25, 2020, Nature-Throid and/or WP-Thyroid are sub-potent, so their manufacturer RLC Labs is issuing a voluntary recall.


“RLC Labs, Inc. is dedicated to the health and safety of our hypothyroid community.

As our number one priority, we want to ensure that you are aware of our decision to issue a recall of all unexpired lots of Nature-Throid® (Thyroid USP Tablets) and WP Thyroid® (Thyroid USP Tablets) that are currently in commercial distribution.

This recall has been initiated because testing found that certain lots of these products may be sub-potent (i.e. contain less than 90% of the labeled amount of liothyronine or levothryroxine).

We have voluntarily decided to recall all unexpired lots in the marketplace to ensure that patients only receive product that meets our high quality standards.

As of this release, we have not been notified of any adverse reactions from patients related to this recall of Nature-Throid® and/or WP Thyroid®.

We are currently working in tandem with the FDA to ensure the quality and safety of our products.”

See the original on the RLC website.

In case they update the notice, a copy is also publicly archived on Archive.org here.

Tell us how much.

They say that their batches were found to be less potent than the FDA permitted variance, <90% on T4 and/or T3, but they won’t say exactly.

UPDATE SEP 6, 2020: “The products are being recalled because testing of samples from  six (6) lots  by the U.S. Food and Drug Administration found the samples to be sub potent. The product may have as low as 87% of the labeled amount of Liothyronine (T3) or Levothyroxine(T4).” (FDA notice ) We still do not know whether it is the T3 or the T4 and which hormone (s) it was in the Nature Throid and the WPThyroid.

In the Acella NP thyroid recall, we were told exactly how much and which hormone was superpotent, so this recall of RLC labs’ Nature-Throid/WP-throid is rather more vague.

Not only that, it is unclear whether Nature-Throid and WP-thyroid are identical in the degree and type of subpotency. Maybe T4 was exactly 87% potency on both brands’ T4, or both brands’ T3, who knows:

  • Reference: 100% potency T4 (38 mcg per 65 mg tablet), 100% potency T3 (9 mcg per 60 mg tablet) according to prescriber’s information.
  • Option 1: Subpotent 87% in T4, meanwhile any shifts can happen within the allowed 90-110% potency in T3 and they don’t have to tell anyone.
  • Option 2: Subpotent 87% in T3, Anywhere within allowed 90-110% potency in T4
  • Option 3: Subpotent 87% in both T3 and T4.

We cannot assume that potency went down from 90% to 87% between lots, when the variability the FDA permits without any recall or notice is 90-110% of the stated potency.

  • The best case scenario was that you were taking a lower-potency batch at 90%, and you had your doses adjusted and were fine. Then you went from 90 to 87% potency on one of the hormones. That’s only a 3.4% loss in potency.
  • In the worst case scenario, you could have been dosed on higher-potency batch at 110% and found your optimal level. And then suddenly whooosh! You’re down at dosing 87% — Therefore, the maximum difference is 26% — you’re losing a quarter of your daily dose of T4 or T3! You’d notice. You’d have to increase your dose!

It makes a difference whether it’s the T3 or the T4 that is subpotent, because each of us converts T4 hormone at different rates. Some of us are poor converters and rely on the T3 content to boost our FT3 levels so we have more active hormone to bind with our receptors.

I’d get my replacement ASAP if I were taking it.

Shrug-worthy underdose?

2020/09/10: This was my first reaction when seeing the original notice, prior to the FDA risk statement being published: Interestingly, RLC Labs first notice didn’t load their recall notice with cautions about horrors in pregnancy outcomes (as Acella’s notice did). However, an underdose from sub-potency to both or the T4 content is far more a risk to pregnancy than an overdose due to superpotency of T3 alone. So, in the US regulatory context, a thyroid medication’s T3 superpotency hits the panic button, while a T3 and/or T4 subpotency that could lead to underdose? Underdose? Shrug. Meh. Let them eat more donuts and coffee. Oh wait. But coffee can reduce absorption of T4 hormone from the gut (Benvega et al, 2008).

But now we have more info about risk, not just a shrug!! …

The FDA risk statement: No longer a shrug.

Risk Section added Sept. 10, 2020

Let’s digest what the FDA announcement says about risks in this recall:

Risk Statement: Patients being treated for hypothyroidism (underactive thyroid), who receive sub potent Nature-Throid® or WP Thyroid®, may experience signs and symptoms of hypothyroidism (underactive thyroid) which may include, fatigue, increased sensitivity to cold, constipation, dry skin, puffy face, hair loss, slow heart rate, depression, swelling of the thyroid gland and/or unexplained weight gain or difficulty losing weight.

There is reasonable risk of serious injury in newborn infants or pregnant women with hypothyroidism including early miscarriage, fetal hyperthyroidism, and/or impairments to fetal neural and skeletal development.

In elderly patients and patients with underlying cardiac disease toxic cardiac manifestations of hyperthyroidism may occur, such as cardiac pain, palpitations or cardiac arrhythmia.

RLC Labs, Inc. has not received any reports of adverse events related to this recall.

On the symptoms of hypothyroidism, we can be thankful for their inclusion of such a detailed list. It is rare to see people care about listing the symptoms of hair loss and weight gain, two things that can be incredibly damaging to our identity and our social lives.

I’m not sure why they mentioned “fetal hyperthyroidism” and “cardiac manifestations of hyperthyroidism” near the end, because this is a potency DEcrease not an INcrease. It looks like filler text someone plunked in without thinking clearly!

Other risks not mentioned?

Symptoms, maternal risks, and cardiovascular risks. These are stereotypical top 3 things to mention. They have to be covered.

But the simple fact is that if they listed all the risks to all the organs and tissues affected by thyroid hormone levels, they would have a list as long as your leg.

There is no disease or disorder in the body that is immune to the effects of a severe reduction in thyroid hormone receptor signalling. Thyroid hormone is just that essential to everything functioning well.

If you have another autoimmune disease, skin disorder or kidney or liver dysfunction, your symptoms and overall health could get worse when you are hypothyroid.

But woe unto the people who are just coming out of surgery, or fighting for their lives in hospital intensive care, or struggling in the final stages of cancer or a neurological disease. You can’t risk being hypothyroid without adequate T3 supply for recovery if you’re in Nonthyroidal Illness.

Click to read more about risk to thyroid patients being hypothyroid during nonthyroidal illness

What is Nonthyroidal illness syndrome (NTIS)? It is a metabolic derangement that happens in all sorts of acute and chronic illnesses and after surgeries and accidents. Your deiodinase type 3 (D3) dumps your thyroid hormones and depletes T3 to lower your metabolic rate very quickly (See GRAPHIC and discussion: T3 Depletion). But sometimes D3 dumps T3 way too far, and T3 stays low for too long. If your TSH was normal to start with, it stays normal during the acute phase (early phase) like an apathetic observer, because the body isn’t ready yet for a T3 refill.

The body will need a T3 refill from a TSH-driven healthy thyroid (or from a hormone pill) to turn it around just at the right time, to aid your recovery of health. If you can’t get your T3 refill at that crucial turning point (whenever that is…), the risk of morbidity and mortality escalates.

Why “woe unto the people…”? Because people on a thyroid hormone leash — people who depend on pills for their thyroid hormone supply — are going to see a loss in T3 levels, too, just like others with healthy thyroids.

  • The natural way to recover is by TSH stimulating a healthy thyroid, which then rapidly secretes more T3 to fill the T3 hole. TSH rises fast, and as TSH rises, the T3 portion of the T3:T4 ratio of thyroidal secretion escalates significantly to give a T3-refill to the body even while there’s still a hole in the T3 bucket. Eventually enough T3 and T4 are in circulation and you can recover.
  • But you, the thyroid disabled person, will need enough T3 from your hormone pill (plus any residual thyroid tissue you may have) to dig yourself out of the hole and to recover health.

GOOD News: Be thankful you’re on a hormone pill that includes some T3, and do not let them switch you to LT4-Levothyroxine while you are in hospital (they can be sneaky if they are programmed to believe that LT4 is best for you!) Bring your supply of NDT. Tell a family member that if you ever go to hospital, they will need to bring your pills to the hospital.

Scientists and doctors are ignorant about our risk as thyroid patients because, as I’ve pointed out before, Thyroid patients are routinely excluded from low T3 syndrome (NTIS) research. It’s called nonthyroidal illness, and we have an illness that is thyroidal but we’re still at risk. But scientists can be easily tricked by language and definitions, so they routinely eliminate us from most research studies of NTIS. Out of ignorance and blind faith, doctors have been told that all we need is our daily T4 dose and we’re fine. No, you can’t say that with enough research. We have to use science and thyroid physiology to surmise what is risky, and not having a thyroid with adjustable TSH-driven T3 secretion rate is a risk because that’s key to recovery!

Why is LT4 therapy bad for you in hospital? An early study on NTIS treatment showed that when they tried to “help” even healthy-thyroid people out of NTIS T3-depletion using T4 hormone alone, it backfired (Brent & Hershman, 1986). That’s because not only did the T4 dosing reduce the strength of their TSH elevation which meant loss of bonus T3 secretion, but also the body was in a mode of D3 enzyme upregulation, converting T4 quickly to RT3 at the same time as converting T3 to various T2s.

Maternal risks

We should be very thankful to them for noticing that risk to fetal life is real. To some people on the borderline of hypothyroidism, a small difference is enough to push them under.

The risk here is very present with REDUCED potency in the T4 portion of desiccated thyroid (NDT). Some women on NDT therapy are superconverters and have a very low FT4 level, hovering near the bottom end of reference, while their FT3 is much higher in range and compensates for the lower FT4.

Click to read more about pregnancy risks with a lower FT4

Pregnancy demands more thyroid hormones in circulation, in general, and FT4 / TT4 (total and free) is the hormone that naturally elevates (even above reference) in people who are pregnant with healthy thyroid glands. (But please do not try to elevate your FT4 above reference using NDT just to mimic their T4 levels! Because of your medication type, your FT3 would be super-high above your FT4 and you’d be overdosed! Just try to keep your FT4 in range bare minimum and half way up the range would be nice, trying to keep your FT3 from spiking too high above reference.)

The risk is that you may already be in your 1st trimester not knowing that you are pregnant, and the fetus really, really needs your maternal hormones in the first trimester. So if you are trying to get pregnant you cannot risk hypothyroidism.

The stablest hormone with the largest supply in blood is T4, and the placenta (which expresses a lot of D3 enzyme) does the labor of filtering the T4 down to levels that the fetus needs. The placenta converts a lot of your T4 to RT3 and only gives the fetus a trickle, and that’s what they need, just enough.

The older studies of fetal risk during pregnancy (1964 to 1970s by Dr. Evelyn Man and associates) focused on UNDERdosed people on desiccated thyroid (Proloid brand) versus women who were dosed with enough T4 supply (the T4 was measured by BEI, Butanol Extracted Iodine, before there was a reliable T4 hormone test. They did not have the technology to measure T3).

  • The women who had enough T4 hormone in circulation while on NDT had perfectly healthy babies with normal mental development by 7 years old. The underdosed women’s children did not fare well.

I don’t have room here to give links to all 10 of these old articles on desiccated thyroid in pregnancy, and most are not fully online anyway. But here is Dr. Man’s most recent article on the topic, in 1991, after a rat study was done by Escobar-Morreale and team, which confirmed some of what Man’s team had found many years previously:

About heart rate / arrhythmias.

Yes, having hypothyroidism will overall slow the heart rate down (bradycardia). The risk with bradycardia can happen when your heart rate goes down naturally at night, especially if you already have sleep apnea. (Read about bradycardia in this US News & World Report article.)

But there are risks beyond slow heart rate in hypothyroidism that many doctors are not aware of:

  • Hypothyroidism (especially low T3) can also cause intermittent spikes in heart rate.
  • Low T3 can also cause heart rhythm problems like atrial fibrillation.
Click to read more about cardiovascular risks in hypothyroidism (underdose, poor T4-T3 conversion)

Fluctuating heart rate in hypothyroidism appears to happen because our adrenal hormones (catecholamines) try to compensate for loss of T3 activity in receptors, and they kick in to keep our heart rate going.

“Thyrotoxic patients have normal plasma norepinephrine (NE) levels, while hypothyroid patients have elevated plasma NE levels, perhaps to compensate for reduced adrenergic sensitivity […]

Epinephrine levels were not different in hyperthyroid or hypothyroid patients compared with normal […]

Catecholamines [such as norepinephrine, etc. secreted from the adrenals] increase T4 to T3 conversion, by stimulating activity of a specific deubiquitinase that acts on the D2 protein, upregulates D2 activity, and increases T3 levels in the nucleus. […](Mullur et al, 2014)

[For scientific readers: What is deubiquitinase? We need D2 to convert a lot of our T4 into T3. The “deubiquitinase” is an enzyme that takes a D2 enzyme that has been temporarily inactivated by being turned into ubiquitin, and turns it back into an active D2 enzyme once again. This means that even a higher-normal T4 level, which usually dulls the D2 enzyme by ubiquitination, will suddenly not suppress D2 as much, and you’ll convert T4 to T3 more efficiently within cells. (The D2 is expressed close to the nucleus in the cytosol of the cell, where it will usher the T3 hormones into the nucleus where they will bind with receptors and send signals.) ]

What is the effect of higher norepinephrine in hypothyhroidism? A tachycardia rush (high heart rate)!

“Norepinephrine, produced by the adrenal medulla, is a stress hormone that increases blood pressure, heart rate, and glucose from energy stores; in the kidneys, it will cause constriction of the smooth muscles, resulting in decreased or inhibited flow to the nephrons.”

(Biology LibreTexts, 41.5A Epinephrine and Norepinephrine)

How quickly does norepinephrine cause a heart rate spike? pretty fast.


During stress or a need for increased cardiac output, the adrenal glands release a hormone called norepinephrine into the bloodstream at the same time that the sympathetic nervous system is also triggered to increase your heart rate. This hormone causes the heart to beat faster, and unlike the sympathetic nervous system that sends an instantaneous and short-lived signal, norepinephrine released into the bloodstream increases the heart rate for several minutes or more.

(Michigan Medicine, Electrical System of the Heart, 2019)

I experienced these erratic tachycardia flares myself when I was in my final 3 months on Synthroid as a poor converter. My FT3 was far below reference (2.9 in a ref range of 3.5 to 6.5), and I was in nonthyroidal illness with a high RT3 of 33 (8-25) and a FT4 at mid range or higher. That kind of biochemistry is high risk (see graph below).

I would be doing nothing, like sitting as a passenger in a car, not feeling stressed, when all of a sudden I’d have a painful squeeze in one of my arteries or areas of my chest. Then my HR would spike up to 115 and be erratically jumping around with odd jaggedy shapes on the heartbeat visualization line as I put my finger on the phone and did a heart rate test.

There is a stereotype out there that heart problems are only seen in hyperthyroidism, and that’s simply not true. Being hypothyroid is not good for people with cardiovascular risks.

There is an “U shaped” risk profile — meaning that the risk is high on both ends, low thyroid hormone and high thyroid hormone. However, it matters what hormone you are low in.

Atrial fibrillation risk in particular

Live link to article: https://onlinelibrary.wiley.com/doi/full/10.1111/jce.14183

Being low in T3 is the biggest risk, followed by high-normal Free T4.

If you are taking a desiccated thyroid pill, the good news is that you likely do not have a “low T3 high T4” profile like many poor converters on LT4 monotherapy.

Instead, you’d likely have the reverse, with higher FT3 than FT4. Your ratio of FT3:FT4 is far healthier for the heart as long as you are not overdosing yourself.

Strange rules about Narrow Therapeutic Index medications

So, back to the topic of potency variability.

Why are thyroid medications permitted to vary so much in potency that they can fall below 90%?

Narrow therapeutic index” (NTI) drugs like synthetic Levothyroxine (LT4) are held to a higher standard than most other drugs, at 95-105% of the labeled potency across its shelf life (FDA, 2009).

However, drugs containing Liothyronine LT3, which provide T3, the more active hormone we metabolize from T4, are not (yet) considered NTI drugs.

Just like all other non-NTI pharma, therefore, desiccated thyroid medications like RLC labs’ Nature Throid, WP-Throid, and even synthetic Cytomel (T3) can vary 20% from pill to pill, or batch to batch, as long as they stay within 90-110% of the stated dose.

It is completely illogical that the FDA says the less active hormone T4 has a narrower therapeutic index than T3. It’s because synthetic levothyroxine gets more attention.

Apparently the levothyroxine provided by desiccated thyroid preparations is not held to the narrower 95-105%.

Very strange. Very illogical. But that’s the way the policies are right now.

Relevant NDT recall posts:

See our extensive 2-part post that went into the background, history and regulatory context of the Acella recall and examined how much much their superpotency could have mattered to our health.

24 thoughts on “RLC Labs issues Nature-Throid and WP-thyroid recall for subpotency

  1. Can’t they just offer a 50% refund, and people can test and increase their dose? With a shortage of thyroid raw material in the world, it seems such a waste. People are complainig about certain batches of Erfa here in Scandinavia.

    1. I agree with you. And with the amount of trouble you have to go through to get these meds into your hand when your body can not handle synthetic T4 is crazy where i live. I have to apply special permit to use specific meds and if I have to switch to other similar I have to apply it again. There is so little options and within the options we have it is hard to get them and now there will be months long break with getting these…It sucks to be thyroid patient.

      1. It does suck to be a thyroid patient! I’m so tired of fighting the battle.

        I gave up on my insurance because they were hounding me (calling) frequently about getting off NDT and instead getting on Synthroid! This seems crazy to me. With that, for almost 3 years, I’ve paid for labs and Nature-throid and other compounded prescriptions out-of-pocket. With this Nature-Throid recall, I got a prescription for compounded thyroid hormone from my doctor And my pharmacy will make it for me at the strength that the Nature-Throid should have been. Then I’ll have labs in 3 months. I just paid for labs a short while ago and I think the Nature-Throid makers should pay for our new labs.

        I am hopeful that this compound will get me back on track. I don’t know why I’ve not done this before. I’ve felt under medicated for a year, but my doctor wanted to try other things – like fixing my gut issues – first. I’m tired.

    2. The gov has been trying to get rid of RCL labs for years — maybe it is the Armour thyroid company or the company that makes synthroid that is trying to get rid or RCL labs?

      I have been taking dessicated .thyroid products for 2 decades and never had a problem unless they changed their formula. .

      I need RCL products. Taking NP is like not taking thyroid meds at all!

  2. Further to my earlier comment about NTI status for levothyroxine:

    The statuses of both levothyroxine and liothyronine as NTI medicines was specifically referenced in the UK MHRA’s Public Assessment Report for the new Iraksin 5 and 10 microgram tablets in September 2019.

    Public Assessment Report National Procedure Iraksin 5 microgram Tablets Liothyronine Sodium 5 microgram Tablets Iraksin 10 microgram Tablets Liothyronine Sodium 10 microgram Tablets

    Discussion is currently ongoing among regulatory authorities in Europe as to whether thyroid hormone replacement therapies including levothyroxine and liothyronine should be considered narrow therapeutic index drugs which would have implications for bioequivalence acceptance criteria.

    This document might not be accessible outwith the UK.

    1. Thanks very much for the information. I’ll be interested in following the outcome of these discussions!

      1. In the context of our leaving the EU, (already having left but under transitional arrangements), I hold out little hope any discussion will be EU-plus-UK-wide.

        Nonetheless, I do believe that this is an important issue. First came to my attention in the MHRA levothyroxine report from 2013:


  3. Few months ago I requested my endo to try NDT after reading that patients prefer it over synthetics. The reply I got is that NDT has potency and quality issues (at least I was allowed to start using synthetic T3) The ‘Stop the Thyroid Madness’ site also has reports describing that many patients using NDT from different manufacturers experienced a return of their hypo symptoms in recent years.

    1. Julien, it is unfortunate to see these manufacturers struggling because some people really do respond better to T3 bound to thyroglobulin rather than sodium. It seems to give less of a jolt than synthetic T3. Almost like a slow release. I wonder if they are being scrutinized more closely by the FDA. It’s a good thing to have quality control. The recall shows that systems are at work to protect patients.

    2. I have been on Nature-Throid for at least 10 years (have never been on any other thyroid med) as prescribed by my naturopath, and have never experienced a problem and have felt good. I think Big Pharma is opposed to any more holistic or naturopathic supplements/meds as it cuts into their profits and (OMG) might be safer and more effective ! There seems to be a lot of scrutiny off & on, especially with the desicated thyroid meds in an attempt to discredit them. Leave them alone – they work !!! Many people do best with both T3 & T4.

      1. Thank you for your reply Joyce!

        For years I have been reading health books about vitamins, minerals and natural substances and I confirm the effort to discredit these substances have been reported by every authors or these books. Natural substances cannot be patented, therefore profits margins are smaller. Capitalism requires maximizing profits for shareholders. The progesterone hormone replacement therapy increased cancer risk because they did not use bioidentical, natural progesterone. Big Pharma needed to make just a small change to the natural hormone molecule, be it a single atom, so that it can be patented. Fortunately for us, being aware that profits are being prioritized over our health puts us in a position of power. But not everybody is made aware of this information and their health is being exploited for profit motive.

        I have not been able to find a way to get Nature-Throid prescribed to me where I live but I will continue to search. I know it would be best to have natural thyroid hormone instead of synthetics.

      2. On thyroid forums A LOT of people have been having trouble with NDT for the last few years. It’s certainly a thing nowadays. From what I understand Armour is the most consistent NDT currently on the market. I’ve seen a lot of people, including my cousin, have some serious issues on both Naturethroid and NP Thyroid. I personally would do a combination of T4 and T3 myself instead. Currently I’m only on T4 but have considered trying T3. I think my next step is to give Tirosint a try and if that doesn’t help add in a little T3.

      3. Thanks for sharing your experiences and those of your peers.

        I believe there should be a place online to report evidence of potency changes, and yet the nature of the evidence is difficult to confirm. A manufacturer could always say that an interfering substance has lowered the absorption rate. Or that person’s underlying thyroid function has altered. Horizontal Pharmacy or consumer is not storing the medication at the appropriate temperature. Thyroid medications are very important to dose precisely, and there’s so many variables. In the end the only real check and balance is to have third party inspections performed by national regulators like the FDA.

  4. First, the URL indicating the six lot numbers does not work ⇢ Page Not Found. Second, if there is a problem with a particular patient then this can be ascertained by checking thyroid function tests (TFTs) (e.g., usTSH, or if you wish to be complete then usTSH, free T3 and free T4.

  5. Yes, “Page Not Found” is what I got also. This is so very frustrating. How far back (batches) does this recall affect? I think it is ever since the “shortage.” After the shortage, things changed for me. The Nature Throid seemed to not be as effective. (I just told my doctor last week, before finding out about this “voluntary recall” that something is off with me. That my thyroid medicine does not seem to be working.” Shaking my head. The deception. I wonder if they caught wind that legal action was possibly brewing. “stopthethyroidmadness.com” has had MANY others who have been experiencing the same things since Nature Throid came back after the shortage.

  6. I am beyond frustrated by this. I have been completely exhausted since I got my prescription filled over a month ago. Like, not wanting to get out of bed tired, gained some weird weight, and just generally feeling blah. Well I get the letter in the mail stating the recall! I’m sorry but how can this happen? How is this allowed to leave the facility without being tested? And just a oops…they are messing with our health here.

  7. Got off nature throid a few years ago and have put on at least 20 lbs. For at least 3 1/2 years never gained a pound until this crap went south. Changed to Armour and it’s just bad and is garbage, I then swapped over to NP Thyroid and worked until Nov. 19 then the next batch was horrible. Went back to Nature throid for a 3 moth period but felt blah, then the recall of NP Thyroid happened. I had fight with CVS to get them to stop selling the recalled batch then the new stuff worked. Now the last batch of NP Thyroid has made my joints hurt so bad I stopped taking it again and I a have been on Synthroid and while it working of I just do not have any energy on the stuff. So here is what I found today, CVS says it will not sell anymore NP Thyroid, maybe what I got id a batch of bad stuff from them. I will now get it from Costco and check the expiration date very close. I know what you people are going through and these companies should be sued class action style until their pockets jingle, that’s all the understand.

Leave a public reply here, on our website.

This site uses Akismet to reduce spam. Learn how your comment data is processed.