Dr. Ron’s Research Review – March 31, 2010

 

This week’s research review has three articles on thyroid. Two are on reverse T3 and the third discusses digestive disorders associated with thyroid disorders.

 

Increased reverse triiodothyronine is associated with shorter survival in independently-living elderly: the Alsanut study

            (Forestier, Vinzio et al. 2009) Download

 

Thyroid hormone concentrations, disease, physical function, and mortality in elderly men

            (van den Beld, Visser et al. 2005) Download

 

Consequences of dysthyroidism on the digestive tract and viscera

(Daher, Yazbeck et al. 2009) Download

 

In the News

Silymarin got some bad press in the LA Times, for a recent study on hepatitis. Link

 

A review from 2005 found that: (Mayer, Myers et al. 2005)

There is no evidence that silymarin affects viral load or improves liver histology in hepatitis B or C. Silymarin compounds likely decrease serum transaminases in patients with chronic viral hepatitis, but do not appear to affect viral load or liver histology.

 

The form of silymarin is very important. A recent Alternative Medicine Review monograph describes Silybin-phosphatidylcholine complex. (2009) Download

 

Dr. Ron

 


Abstracts

Increased reverse triiodothyronine is associated with shorter survival in independently-living elderly: the Alsanut study

            (Forestier, Vinzio et al. 2009) Download

OBJECTIVE: Increased reverse tritiodothyronine (T(3)) used to be described as a part of euthyroid sick syndrome (ESS). It was demonstrated to be associated with increased mortality in acutely ill patients. It can also be found with low or normal T(3) in non-severely ill subjects but its significance remains unclear. PATIENTS AND DESIGN: The Alsanut study included a representative sample of 440 independently-living subjects aged 65 or over constituted between January 1988 and September 1989. Past and current medical history and nutritional data were collected at inclusion. Baseline thyroid hormone (TSH, FT(4), FT(3) and rT(3)) serum levels were measured. Life status was determined on 1 December 2005. RESULTS: Of the 374 elderly subjects included in the final analysis, 52 had abnormal TSH (43 with hyperthyroidism, nine with hypothyroidism) and 80.7% had died by 1 December 2005. There was no statistical difference in survival between subjects according to thyroid function (P=0.54). Of the 322 elderly subjects with normal TSH, mortality rate was 81.1%. ESS was found in 3.4%, whereas 8.1% of the participants displayed elevated rT(3) with normal FT(3). Time to death was strongly related to rT(3) (P<0.0001) and FT(3) (P<0.0001) in a univariate analysis. After adjusting for other confounding variables, rT(3) was the only thyroid hormone associated with shorter survival (P=0.014). CONCLUSIONS: RT(3) was the only thyroid hormone associated with shorter survival in a representative population of independently-living elderly. In these subjects, isolated elevated rT(3) might be an equivalent of ESS, reflecting declining health.

 

Thyroid hormone concentrations, disease, physical function, and mortality in elderly men

            (van den Beld, Visser et al. 2005) Download

CONTEXT: Physiological changes in thyroid hormone concentrations might be related to changes in the overall physical function in the elderly. OBJECTIVE: We determined to what extent thyroid hormone concentrations are related to physical function and mortality in elderly men. DESIGN: A longitudinal population study (the Zoetermeer study) was conducted. Mortality was registered in the subsequent 4 yr. PARTICIPANTS: Four hundred three independently and ambulatory living men (aged 73-94 yr) participated. MAIN OUTCOME MEASURES: The study examined the association between serum thyroid hormones and parameters of physical function as well as the association with mortality. METHODS: TSH, free T4 (FT4) total T4, T3, rT3, and T4-binding globulin were measured. Physical function was estimated by the number of problems in activities of daily living, a measure of physical performance score (PPS), leg extensor strength and grip strength, bone density, and body composition. RESULTS: Serum rT3 increased significantly with age and the presence of disease. Sixty-three men met the biochemical criteria for the low T3 syndrome (decreased serum T3 and increased serum rT3). This was associated with a lower PPS, independent of disease. Furthermore, higher serum FT4 (within the normal range of healthy adults) and rT3 (above the normal range of healthy adults) were related with a lower grip strength and PPS, independent of age and disease. Isolated low T3 was associated with a better PPS and a higher lean body mass. Low FT4 was related to a decreased risk of 4-yr mortality. CONCLUSIONS: In a population of independently living elderly men, higher FT4 and rT3 concentrations are associated with a lower physical function. High serum rT3 may result from a decreased peripheral metabolism of thyroid hormones due to the aging process itself and/or disease and may reflect a catabolic state. Low serum FT4 is associated with a better 4-yr survival; this may reflect an adaptive mechanism to prevent excessive catabolism.

 

Consequences of dysthyroidism on the digestive tract and viscera

(Daher, Yazbeck et al. 2009) Download

Thyroid hormones define basal metabolism throughout the body, particularly in the intestine and viscera. Gastrointestinal manifestations of dysthyroidism are numerous and involve all portions of the tract. Thyroid hormone action on motility has been widely studied, but more complex pathophysiologic mechanisms have been indicated by some studies although these are not fully understood. Both thyroid hormone excess and deficiency can have similar digestive manifestations, such as diarrhea, although the mechanism is different in each situation. The liver is the most affected organ in both hypo- and hyperthyroidism. Specific digestive diseases may be associated with autoimmune thyroid processes, such as Hashimoto's thyroiditis and Grave's disease. Among them, celiac sprue and primary biliary cirrhosis are the most frequent although a clear common mechanism has never been proven. Overall, thyroid-related digestive manifestations were described decades ago but studies are still needed in order to confirm old concepts or elucidate undiscovered mechanisms. All practitioners must be aware of digestive symptoms due to dysthyroidism in order to avoid misdiagnosis of rare but potentially lethal situations.

 


References

(2009). "Silybin-phosphatidylcholine complex. Monograph." Altern Med Rev 14(4): 385-90.

Daher, R., T. Yazbeck, et al. (2009). "Consequences of dysthyroidism on the digestive tract and viscera." World J Gastroenterol 15(23): 2834-8.

Forestier, E., S. Vinzio, et al. (2009). "Increased reverse triiodothyronine is associated with shorter survival in independently-living elderly: the Alsanut study." Eur J Endocrinol 160(2): 207-14.

Mayer, K. E., R. P. Myers, et al. (2005). "Silymarin treatment of viral hepatitis: a systematic review." J Viral Hepat 12(6): 559-67.

van den Beld, A. W., T. J. Visser, et al. (2005). "Thyroid hormone concentrations, disease, physical function, and mortality in elderly men." J Clin Endocrinol Metab 90(12): 6403-9.