Desiccated thyroid extract
Encyclopedia
Desiccated thyroid or thyroid extract, refers to porcine
(or mixed beef and pork) thyroid
glands, dried and powdered for therapeutic
use. As an animal product
, it is not suitable for use by vegetarians. Some religious dietary laws object to the use of pork
products as well, although exceptions are sometimes made for medicinal uses. Pork (or mixed beef and pork) thyroid preparations were developed in the late 19th century, and are still used today to treat hypothyroidism
, the condition of having an underactive thyroid gland. This product is sometimes referred to as "natural thyroid", "natural thyroid hormones", "pork thyroid", thyroid USP
, thyroid BP
, or by the name of a commercial brand, such as "Armour Thyroid".
Desiccated thyroid has been described in the United States Pharmacopoeia for nearly a century as the cleaned, dried, and powdered thyroid gland previously deprived of connective tissue and fat... obtained from domesticated animals that are used for food by man (USP XVI). In the last few decades, pork alone is the usual source. Historically, before modern assays, the potency was specified only by iodine
content ("not less than 0.17% and not more than 0.23%"), rather than hormonal content or activity.
Brands include Forest Lab's Armour, Naturethroid & Westhroid by RLC Labs, and NP Thyroid by Acella Pharmaceuticals. Canada's desiccated thyroid is made by Erfa and is called Thyroid. All consist of desiccated porcine thyroid powder, differing only in the binders and fillers.
All brands contain a mixture of thyroid hormones: T4 (thyroxine
), T3 (triiodothyronine
) in the proportions usually present in pig thyroids (approximately 80% T4 and 20% T3). Armour is made in the following strengths: 1/8, 1/4, 1/2, 1, 2, and 3 grain as well as 4 and 5 grain tablets. One grain (about 60 mg) of desiccated thyroid contains about 38 mcg of T4 and 9 mcg of T3. Because the preparation is whole thyroid gland, each 60 mg tablet also contains over 59 mg of all of the other constituents of pork thyroid glands.
of the United Kingdom
first described treatment of myxedema
with thyroid extract in 1891, and published a description of long-term successful treatment (28 years) of a patient with myxedema (severe hypothyroidism) in 1920 His treatment was quickly adopted in North America and Europe. The first recorded American use dates to 1891 by a woman who was still taking it 52 years later at 84 years of age
Desiccated thyroid extract is prepared from pig and cow thyroid glands. The glands are dried (desiccated), ground to powder, combined with binder chemicals, and pressed into pills. This was a new use for parts that were previously unwanted slaughterhouse
offal
, and Armour and Company
, the dominant American meatpacker in the 20th century, supplied the best-known brand of thyroid extract.
Replacement by thyroid extract in hypothyroidism was one of the most effective treatments of any disease available to physicians before the middle of the 20th century, and in severe cases afforded dramatic relief of the myriad symptoms. The decision to treat was usually based on the presence of signs and symptoms of hypothyroidism because there were no accurate, readily available laboratory tests
of thyroid function. Many less severe cases of hypothyroidism went untreated. Dosage was regulated by improvement of symptom
s.
In the early 1960s, desiccated thyroid hormones (thyroid extract) began to be replaced by levothyroxine
(T4), or by combinations of T4 and T3. Replacement occurred faster in the United Kingdom than in North America, but by the 1980s more patients were being prescribed levothyroxine or T4/T3 combinations than desiccated thyroid extract.
Several reasons have been identified as to why prescriptions changed from the previously-effective desiccated thyroid treatment. These factors included a desire for improved effectiveness, medical evidence, scientific theory, cultural fashion, and effective marketing.
Thyroid care changed in other ways as well. Accurate T4 and T3 measurements became widely used in the 1970s, and by the late 1980s, TSH measurement had become sensitive enough to detect mild degrees of hyperthyroidism
and overtreatment. To no one's surprise, blood levels of thyroid hormones and TSH were found to be the best predictors of objective benefits from thyroid replacement: those with the most severe measurable deficiency enjoyed the most dramatic and sustained benefits. It was also discovered that even mild hyperthyroidism
as defined by a suppressed TSH level, whether due to disease or overtreatment, was associated with poorer bone density
in women, and with higher rates of atrial fibrillation
in elderly patients. Doctors began to trust the TSH measurement more and more as the index of optimal replacement dose.
As more doctors prescribed thyroxine instead of thyroid extract, the use of thyroid extract became associated with those whose medical practices deviated in many ways from standard care. (See complementary and alternative medicine.) This association became a disincentive for using thyroid extract, and those prescribing it were considered to be unscientific and irrational practitioners.
A number of specific claims are commonly made about thyroid extract:
To endocrinologists the preference of some hypothyroid people for thyroid extract raises some important questions which current evidence cannot answer with certainty:
Despite claims of proponents that desiccated thyroid pills are superior to thyroxine or combinations of T4 and T3 for most people with hypothyroidism, no controlled clinical trials have been published, and many physicians remain unconvinced that the superiority is anything other than a placebo effect or an overtreatment effect.
has recommended the exclusive use of synthetic levothyroxine for the treatment of hypothyroidism.
Pig
A pig is any of the animals in the genus Sus, within the Suidae family of even-toed ungulates. Pigs include the domestic pig, its ancestor the wild boar, and several other wild relatives...
(or mixed beef and pork) thyroid
Thyroid
The thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
glands, dried and powdered for therapeutic
Medication
A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...
use. As an animal product
Animal product
Animal product, or animal by-product, is a term used to describe material taken from the body of a non-human animal. Examples are fat, flesh, blood, milk, eggs, and lesser known products such as isinglass and rennet....
, it is not suitable for use by vegetarians. Some religious dietary laws object to the use of pork
Pork
Pork is the culinary name for meat from the domestic pig , which is eaten in many countries. It is one of the most commonly consumed meats worldwide, with evidence of pig husbandry dating back to 5000 BC....
products as well, although exceptions are sometimes made for medicinal uses. Pork (or mixed beef and pork) thyroid preparations were developed in the late 19th century, and are still used today to treat hypothyroidism
Hypothyroidism
Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.Iodine deficiency is the most common cause of hypothyroidism worldwide but it can be caused by other causes such as several conditions of the thyroid gland or, less commonly, the pituitary gland or...
, the condition of having an underactive thyroid gland. This product is sometimes referred to as "natural thyroid", "natural thyroid hormones", "pork thyroid", thyroid USP
United States Pharmacopeia
The United States Pharmacopeia is the official pharmacopeia of the United States, published dually with the National Formulary as the USP-NF. The United States Pharmacopeial Convention is the nonprofit organization that owns the trademark and copyright to the USP-NF and publishes it every year...
, thyroid BP
British Pharmacopoeia
The British Pharmacopoeia is an annual published collection of quality standards for UK medicinal substances. It is used by individuals and organizations involved in pharmaceutical research, development, manufacture and testing....
, or by the name of a commercial brand, such as "Armour Thyroid".
Desiccated thyroid has been described in the United States Pharmacopoeia for nearly a century as the cleaned, dried, and powdered thyroid gland previously deprived of connective tissue and fat... obtained from domesticated animals that are used for food by man (USP XVI). In the last few decades, pork alone is the usual source. Historically, before modern assays, the potency was specified only by iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
content ("not less than 0.17% and not more than 0.23%"), rather than hormonal content or activity.
Brands include Forest Lab's Armour, Naturethroid & Westhroid by RLC Labs, and NP Thyroid by Acella Pharmaceuticals. Canada's desiccated thyroid is made by Erfa and is called Thyroid. All consist of desiccated porcine thyroid powder, differing only in the binders and fillers.
All brands contain a mixture of thyroid hormones: T4 (thyroxine
Thyroxine
Thyroxine, or 3,5,3',5'-tetraiodothyronine , a form of thyroid hormones, is the major hormone secreted by the follicular cells of the thyroid gland.-Synthesis and regulation:...
), T3 (triiodothyronine
Triiodothyronine
Triiodothyronine, C15H12I3NO4, also known as T3, is a thyroid hormone. It affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate....
) in the proportions usually present in pig thyroids (approximately 80% T4 and 20% T3). Armour is made in the following strengths: 1/8, 1/4, 1/2, 1, 2, and 3 grain as well as 4 and 5 grain tablets. One grain (about 60 mg) of desiccated thyroid contains about 38 mcg of T4 and 9 mcg of T3. Because the preparation is whole thyroid gland, each 60 mg tablet also contains over 59 mg of all of the other constituents of pork thyroid glands.
History
The earliest oral treatment for hypothyroidism consisted of thyroid extract. George Redmayne MurrayGeorge Redmayne Murray
George Redmayne Murray was an English physician who pioneered in the treatment of endocrine disorders. In 1891, he introduced the successful treatment of myxedema, with injections of sheep thyroid extract....
of the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
first described treatment of myxedema
Myxedema
Myxedema describes a specific form of cutaneous and dermal edema secondary to increased deposition of connective tissue components in subcutaneous tissue as seen in various forms of hypothyroidism and Graves' disease. It is more common in women than in men...
with thyroid extract in 1891, and published a description of long-term successful treatment (28 years) of a patient with myxedema (severe hypothyroidism) in 1920 His treatment was quickly adopted in North America and Europe. The first recorded American use dates to 1891 by a woman who was still taking it 52 years later at 84 years of age
Desiccated thyroid extract is prepared from pig and cow thyroid glands. The glands are dried (desiccated), ground to powder, combined with binder chemicals, and pressed into pills. This was a new use for parts that were previously unwanted slaughterhouse
Slaughterhouse
A slaughterhouse or abattoir is a facility where animals are killed for consumption as food products.Approximately 45-50% of the animal can be turned into edible products...
offal
Offal
Offal , also called, especially in the United States, variety meats or organ meats, refers to the internal organs and entrails of a butchered animal. The word does not refer to a particular list of edible organs, which varies by culture and region, but includes most internal organs other than...
, and Armour and Company
Armour and Company
Armour & Company was an American slaughterhouse and meatpacking company founded in Chicago, Illinois, in 1867 by the Armour brothers, led by Philip Danforth Armour. By 1880, the company was Chicago's most important business and helped make the city and its Union Stock Yards the center of the...
, the dominant American meatpacker in the 20th century, supplied the best-known brand of thyroid extract.
Replacement by thyroid extract in hypothyroidism was one of the most effective treatments of any disease available to physicians before the middle of the 20th century, and in severe cases afforded dramatic relief of the myriad symptoms. The decision to treat was usually based on the presence of signs and symptoms of hypothyroidism because there were no accurate, readily available laboratory tests
Medical test
A diagnostic test is any kind of medical test performed to aid in the diagnosis or detection of disease. For example:* to diagnose diseases, and preferably sub-classify it regarding, for example, severity and treatability...
of thyroid function. Many less severe cases of hypothyroidism went untreated. Dosage was regulated by improvement of symptom
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
s.
In the early 1960s, desiccated thyroid hormones (thyroid extract) began to be replaced by levothyroxine
Levothyroxine
Levothyroxine, also L-thyroxine, synthetic T4, or 3,5,3',5'-tetraiodo-L-thyronine, is a synthetic form of thyroxine , used as a hormone replacement for patients with thyroid problems. The natural hormone is chemically in the chiral L-form, as is the pharmaceutical agent...
(T4), or by combinations of T4 and T3. Replacement occurred faster in the United Kingdom than in North America, but by the 1980s more patients were being prescribed levothyroxine or T4/T3 combinations than desiccated thyroid extract.
Several reasons have been identified as to why prescriptions changed from the previously-effective desiccated thyroid treatment. These factors included a desire for improved effectiveness, medical evidence, scientific theory, cultural fashion, and effective marketing.
- Although thyroid extract was useful and usually effective, some patients continued to complain of fatigue, weight gain, or other symptoms. Dosing until the 1960s was often a matter of prolonged adjustment trials.
- It was known that not all of the iodine content of thyroid extract was in the form of effective T4 and T3 and that actual content of available preparations varied more than the permitted 15%. It was hoped that better dosing precision with levothyroxine alone would increase the proportion of patients effectively treated. In 1980, a widely publicized investigation published in JAMAJournal of the American Medical AssociationThe Journal of the American Medical Association is a weekly, peer-reviewed, medical journal, published by the American Medical Association. Beginning in July 2011, the editor in chief will be Howard C. Bauchner, vice chairman of pediatrics at Boston University’s School of Medicine, replacing ...
revealed continued large ranges of hormone content and potency in all of the available thyroid extracts on the American market. - By the 1960s, it was known that thyroxine was the essential hormone produced by the thyroid gland, and that most T3 was manufactured in other parts of the body by deiodination of thyroxine. It was demonstrated in hypothyroid animals and people that replacement of thyroxine alone corrected the measurable manifestations(laboratory test numbers) of hypothyroidism. By the 1970s doctors could measure T4, T3, and TSHTSHTSH may refer to:* Tanzanian shilling, the currency of Tanzania* Thyroid-stimulating hormone, a hormone synthesized and secreted by thyrotrope cells* Tshiuetin Rail Transportation, a Canadian railway between Labrador and Quebec...
in human blood with approximate accuracy and confirmed that treatment with thyroxine alone could produce normal blood levels of both T4 and T3, but desiccated thyroid caused supraphysiologic levels of T3. In the majority of patients normalization of these levels eliminated all signs and symptoms of hypothyroidism. - It was discovered that a healthy person varied the amount of T3 produced from T4 in response to changing needs and conditions and it seemed wiser not to bypass this control system by providing larger amounts of T3 than were naturally produced each day.
- Furthermore, when T3 could be measured, it was discovered that thyroid extract and synthetic combinations of T4 and T3 produced significantly greater fluctuations of T3 throughout the day than occurred in healthy people or hypothyroid people treated with thyroxine alone.
- EndocrinologistsEndocrinologyEndocrinology is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions called hormones, the integration of developmental events such as proliferation, growth, and differentiation and the coordination of...
found that treatment with thyroxine alone worked as well or better than thyroid extract for the majority of patients, although even thyroxine did not reverse all the symptoms of a minority. - Cultural fashion and marketing played a role. In the middle of the 20th century, pharmaceutical chemistsMedicinal chemistryMedicinal chemistry and pharmaceutical chemistry are disciplines at the intersection of chemistry, especially synthetic organic chemistry, and pharmacology and various other biological specialties, where it is involved with design, chemical synthesis and development for market of pharmaceutical...
had been discovering the active molecules in a variety of plant and animal remedies, from aspirinAspirinAspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...
and digitoxinDigitoxinDigitoxin is a cardiac glycoside. It has similar structure and effects to digoxin . Unlike digoxin , it is eliminated via the liver, so could be used in patients with poor or erratic kidney function. However, it is now rarely used in current Western medical practice...
to vitaminVitaminA vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on...
s, and producing them synthetically with improvements in purity and dosage control. In that cultural context, it was easy to market pure levothyroxine as superior to dried animal glands. - Synthroid, one of the most successful brand names in pharmaceutical marketingPharmaceutical marketingPharmaceutical marketing , sometimes called medico-marketing, is the business of advertising or otherwise promoting the sale of pharmaceuticals or drugs. There is some evidence that marketing practices can negatively affect both patients and the health care profession...
history, became as synonymous with thyroid replacement to generations of American primary carePrimary carePrimary care is the term for the health services by providers who act as the principal point of consultation for patients within a health care system...
doctors as KleenexKleenexKleenex is a brand name for a variety of toiletry paper-based products such as facial tissue, bathroom tissue, paper towels, and diapers. The name Kleenex is a registered trademark of Kimberly-Clark Worldwide, Inc. Often used as a genericized trademark, especially in the United States, "Kleenex"...
or XeroxXeroxXerox Corporation is an American multinational document management corporation that produced and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies...
became with their respective products.
Thyroid care changed in other ways as well. Accurate T4 and T3 measurements became widely used in the 1970s, and by the late 1980s, TSH measurement had become sensitive enough to detect mild degrees of hyperthyroidism
Hyperthyroidism
Hyperthyroidism is the term for overactive tissue within the thyroid gland causing an overproduction of thyroid hormones . Hyperthyroidism is thus a cause of thyrotoxicosis, the clinical condition of increased thyroid hormones in the blood. Hyperthyroidism and thyrotoxicosis are not synonymous...
and overtreatment. To no one's surprise, blood levels of thyroid hormones and TSH were found to be the best predictors of objective benefits from thyroid replacement: those with the most severe measurable deficiency enjoyed the most dramatic and sustained benefits. It was also discovered that even mild hyperthyroidism
Hyperthyroidism
Hyperthyroidism is the term for overactive tissue within the thyroid gland causing an overproduction of thyroid hormones . Hyperthyroidism is thus a cause of thyrotoxicosis, the clinical condition of increased thyroid hormones in the blood. Hyperthyroidism and thyrotoxicosis are not synonymous...
as defined by a suppressed TSH level, whether due to disease or overtreatment, was associated with poorer bone density
Bone density
Bone density is a medical term normally referring to the amount of mineral matter per square centimeter of bones. Bone density is used in clinical medicine as an indirect indicator of osteoporosis and fracture risk.This medical bone density is not the true physical "density" of the bone, which...
in women, and with higher rates of atrial fibrillation
Atrial fibrillation
Atrial fibrillation is the most common cardiac arrhythmia . It is a common cause of irregular heart beat, identified clinically by taking a pulse. Chaotic electrical activity in the two upper chambers of the heart result in the muscle fibrillating , instead of achieving coordinated contraction...
in elderly patients. Doctors began to trust the TSH measurement more and more as the index of optimal replacement dose.
As more doctors prescribed thyroxine instead of thyroid extract, the use of thyroid extract became associated with those whose medical practices deviated in many ways from standard care. (See complementary and alternative medicine.) This association became a disincentive for using thyroid extract, and those prescribing it were considered to be unscientific and irrational practitioners.
Thyroid extract proponents
Desiccated thyroid is preferred by a growing body of patients and doctors who claim better relief of symptoms such as fatigue and depressed mood. Many proponents of desiccated thyroid feel passionately about the issue. .A number of specific claims are commonly made about thyroid extract:
- Thyroid extract is better than thyroxine because it contains both T4 and T3, and both are made by a healthy thyroid gland.
- Doses should be increased until symptoms are relieved regardless of laboratory tests.
- Other constituents of the dried thyroid glands besides the T4 and T3 (e.g., unmeasured amounts of diiodothyronine (T2), monoiodothyronine (T1), calcitoninCalcitoninCalcitonin is a 32-amino acid linear polypeptide hormone that is producedin humans primarily by the parafollicular cells of the thyroid, and in many other animals in the ultimobranchial body. It acts to reduce blood calcium , opposing the effects of parathyroid hormone . Calcitonin has been found...
, other protein-bound iodine) may contribute to a perceived greater effectiveness or confer additional benefits. - A product produced by farmFarmA farm is an area of land, or, for aquaculture, lake, river or sea, including various structures, devoted primarily to the practice of producing and managing food , fibres and, increasingly, fuel. It is the basic production facility in food production. Farms may be owned and operated by a single...
, slaughterhouseSlaughterhouseA slaughterhouse or abattoir is a facility where animals are killed for consumption as food products.Approximately 45-50% of the animal can be turned into edible products...
, and factory is "natural", and therefore preferable to thyroxine molecules synthesized in a factory alone.
To endocrinologists the preference of some hypothyroid people for thyroid extract raises some important questions which current evidence cannot answer with certainty:
- Is the reason some people fail to have complete relief of symptoms when tests show normal levels simply because there are other causes of fatigue, depression, and weight gain and these people are mistakenly attributing the problems to the thyroid and simply enjoying a placebo effectPlacebo effectPlacebo effect may refer to:* Placebo effect, the tendency of any medication or treatment, even an inert or ineffective one, to exhibit results simply because the recipient believes that it will work...
if they claim better relief from thyroid extract? - Does a combination of T4 and T3 provide more effective symptom relief for some people than T4 alone? Multiple controlled trials have shown inconsistent benefits of various ratios of T4 and T3. Even if most people with hypothyroidism enjoy complete relief of symptoms with thyroxine alone, are there people who need T3 as well because they cannot generate normal amounts from T4 as most people do?
- Is the perceived benefit simply a result of overtreatment, such that the same relief could be achieved by pushing a thyroxine dose to higher levels?
- Is the TSH measurement, and its associated 'normal' range, the best indicator of optimal replacement dose? Most research evidence suggests it is, but some patients feel better at doses which produce abnormally high blood levels of T4 and T3 and suppressed TSH. Is this simply a stimulant effect of high doses, similar to caffeineCaffeineCaffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...
or amphetamineAmphetamineAmphetamine or amfetamine is a psychostimulant drug of the phenethylamine class which produces increased wakefulness and focus in association with decreased fatigue and appetite.Brand names of medications that contain, or metabolize into, amphetamine include Adderall, Dexedrine, Dextrostat,...
? How high is the risk of prolonged overtreatment to the boneBoneBones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
s, heartHeartThe heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
, and other parts of the body, and is it worth an improvement in subjective well-being?
Despite claims of proponents that desiccated thyroid pills are superior to thyroxine or combinations of T4 and T3 for most people with hypothyroidism, no controlled clinical trials have been published, and many physicians remain unconvinced that the superiority is anything other than a placebo effect or an overtreatment effect.
Current status of thyroid extract use
At present, a large majority of people (at least in the English-speaking world) of all ages with hypothyroidism are being treated with levothyroxine. When their blood levels of thyroid hormones and TSH are most normal, the majority have no more signs or symptoms of hypothyroidism than similar members of the population. The Royal College of PhysiciansRoyal College of Physicians
The Royal College of Physicians of London was founded in 1518 as the College of Physicians by royal charter of King Henry VIII in 1518 - the first medical institution in England to receive a royal charter...
has recommended the exclusive use of synthetic levothyroxine for the treatment of hypothyroidism.
Books
There are several books promoting thyroid hormone replacement with desiccated thyroid:- Janie A. Bowthorpe. "Stop the Thyroid Madness: a Patient Revolution Against Decades of Inferior Treatment". Laughing Grape Publishing, 2008. ISBN 978-0-615-14431-3 Revised Edition: 2011. ISBN 978-0-615-47712-1
- Dr. David Brownstein. Overcoming Thyroid Disorders. Medical Alternatives Press, 2002. ISBN 0-9660882-2-0.
- Barry Durrant-Peatfield. The Great Thyroid Scandal and How To Survive It. Barons Down Publishing, 2002. ISBN 0-9544203-0-6.
- Steven F. Hotze. Hormones, Health, and Happiness. Forrest Publishing, 2005. ISBN 0-9765751-0-8.
- Mary Shomon. Living Well With Hypothyroidism: What Your Doctor Doesn't Tell You...That You Need to Know. HarperCollins, 2005. ISBN 0-0607409-5-7.