Bioidentical Hormones 101 
The Book, by Jeffrey Dach MD

Chapter 4. Why Natural Thyroid is Better than Synthroid, Part Two

thyroxine,synthroid,natural, thyroid,rlc lab,armour,forrest lab, osteoporosisChapter 4.  Why Natural Thyroid is

Better than Synthroid, Part Two

Will Thyroid Medication Give Me Osteoporosis ?

New concerns were raised by Dr. Marci Turner in the April 2011 British Medical Journal reporting elderly women on Synthroid(tm) have increased fracture risk.(13)  Note: Synthroid is a T4-only medication, also called thyroxine or levothyroxine.  A 2010 report by Murphy looked at thyroid function and fracture risk in normal postmenopausal women, and they found a 35% increase in fracture risk in women with lower TSH values (TSH=thyroid stimulating hormone). (1)  Higher TSH was protective of fracture.

Above left image : Thyroxine Chemical structure, courtesy of Wikimedia commons.

No Real Consensus on The Issue

To add confusion to the issue, a 2003 meta-analysis by Schneider reviewed 63 studies looking at the effect of thyroid medication (T4-only) on bone mineral density, finding no real consensus and concluding that, "currently debate still exists about the effects of thyroid hormone therapy on skeletal integrity, that is the safety of levothyroxine use with respect to bone mineral density." (14)(15)  Let us take a look at this issue and try to come up with some real answers.

The Calcitonin Connection

The thyroid gland not only makes thyroid hormone.  It also makes Calcitonin, a hormone manufactured by the parafollicular calls (C cells) in the thyroid tissue. (24)   Calcitonin is involved in calcium metabolism, bone maintenance and prevents osteoporosis.  

Thyroid Disorders Cause Destruction of Calcitonin Cells

Hashimoto's Thyroiditis is a common cause of hypothyroidism and is associated with destruction of the C-cells with loss of Calcitonin production. (2-4) The resulting Calcitonin deficiency is a potential cause of bone resorption and osteoporosis. (7-12) On the other hand, treatment with Calcitonin nasal spray is an FDA approved treatment for osteoporosis and is shown to increase bone density. (16) 

Hashimoto's, Radio-Iodine and Surgery all Destroy Calcitonin Cells

All three, the autoimmune process of Hashimoto’s Thyroiditis, Radioactive Iodine ablation and Thyroid surgical ablation, serve to reduce or eliminate thyroid function, and the C-cells which make Calcitonin get knocked out as well.  Synthroid, levothyroxine, and T4-only medications do not provide the missing Calcitonin.  One would expect the Calcitonin deficient patient to be at greater risk for osteoporosis and fracture.  Unlike Synthroid and T4-only medications which DO NOT contain Calcitonin, natural desiccated thyroid pills DO CONTAIN Calcitonin, providing the missing hormone, and is the preferred form of thyroid medication.  

Oral Absorption of Porcine Calcitonin

Since Calcitonin is a small peptide, it is subject to degradation and digestion when taken by the oral route.  To avoid the oral route, Porcine Calcitonin is given as intramuscular injection, and salmon Calcitonin which is 25 times more potent is given as intranasal spray.  Newer Calcitonin formulations use some type of carrier to allow for oral dosing.  Studies show that oral absorption of Calcitonin is a small fraction of the ingested dose, about 0.022%, yet even this small amount has a physiologic effect with a drop in serum calcium observed.(41)   How much Calcitonin is in a One Grain natural thyroid pill?  We don’t know the exact amount.  Obviously, further medical research in this area is needed.

None of the Studies Used Natural Desiccated Thyroid

Unfortunately, all of the medical studies of the bone density-thyroid connection used T4-only medication, none used desiccated natural thyroid, so we don't have any studies to evaluate the long term lack of osteoporosis from natural desiccated thyroid.  NIH funded research is needed to evaluate bone density and fracture risk for natural desiccated thyroid compared to T4-only medications.   Will this ever take place? Don't hold your breath.  The NIH is a government agency, and the government is influenced by Big Pharma dollars, so natural is out and synthetic is in.  We may never see NIH funding for research on natural desiccated thyroid.  

The TSH Connection, TSH is Protective and Prevents Bone Resorption

Advances in our understanding of physiology and animal research have revealed TSH hormone (thyroid stimulating hormone) has a direct effect on bone cells, preventing degradation of bone and bone resorption, and therefore protective of bone density.(17-19)  This could explain the many studies that find a correlation between higher TSH and improved bone density.  The problem with using TSH as a treatment for osteoporosis is that higher TSH is associated with increased heart disease (see the HUNT study), as well as a host of low thyroid symptoms of fatigue, malaise, muscle aches and pains etc.(25)  Patients feel better with a lower TSH and higher thyroid function, so cutting back on thyroid medication to let the TSH drift up may be good for bone density, but it is not good for the patient.

Good News About Bioidentical Hormones

The good news is that the TSH effect on bone density is relatively modest and is offset by the addition of estrogen, a bioidentical hormone, which increases bone density. (20)  In addition, we routinely employ a natural bone building program.  One of the interventions is to measure and optimize vitamin D levels which protects and maintains bone density.  In my experience with our TrueMedMD clinic patients using natural thyroid and bioidentical hormones, we have seen only benefits with increasing bone density, and no observed cases of osteoporosis. 

In conclusion, an excellent reason to switch from T4-only thyroid medication to natural desiccated thyroid is because it contains Calcitonin, protective of bone density and preventive of osteoporosis.  T4-only medication does not contain Calcitonin and is associated with loss of bone density and increased fracture risk.  We have found good clinical results with a natural desiccated thyroid product called Naturethroid from RLC labs. Dosage range is from one to four Grains per day depending on underlying thyroid function and body weight.  We pay close attention to clinical symptom resolution during the follow up period.  For lab monitoring, we follow the advice of Jonathan Wright MD who advocates the use of the serum Free T3 test, as more useful than the TSH test.

This is Part Two of a series, for Part One Click Here.

Articles with Related Interest:

Why Natural Thyroid is Better than Synthetic Part One
Why Natural Thyroid is Better than Synthetic Part Two
Why Natural Thyroid is Better than Synthetic Part Three

References  for Chapter 4, Why Natural Thyroid is Better than Synthetic Part Two

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(25) Hunt Study Shows Thyroid Prevents Heart Attacks by Jeffrey Dach MD

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(41)  Utility of pharmacodynamic measures for assessing the oral bioavailability of peptides. 1. Administration of recombinant salmon calcitonin in rats. Patrick J. Sinko1 et al. J Pharm Sci. 1995 Nov;84(11):1374-8.  The absorption of rsCT after id. (Duodenal)administration was low (0.022%); however, a significant lowering of serum calcium concentrations was observed.

author: Jeffrey Dach MD  Dr Dach

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