Il selenio: un valore aggiunto ?

Michele ZiniUnità Operativa di EndocrinologiaArcispedale S. Maria Nuova IRCCS, Reggio EmiliaMichele.zini@asmn.re.it

Indice

• Selenio• Selenio e tiroidite autoimmune• Selenio e m. di Graves• Selenio e gravidanza

Selenium Duntas LH et al., European Journal of Endocrinology 148: 389–393, 2003

• Selenium is an essential component of the glutathione peroxidase enzymes and of thioredoxin reductase which protects tissues from oxidative damage

• Selenium is contained in the iodothyronine selenodeiodinases, D1 and D2, which are responsible for the production of biologically active triiodothyronine via 50-deiodination

• Thus, selenium deficiency may seriously influence the generation of free radicals, the conversion of T4 to T3 and the autoimmune process

Selenium in autoimmune thyroiditisGärtner R et al., J Clin Endocrinol Metab 87: 1687–1691, 2002

Free T4 and T3 as well as TSH values were unchanged in both groups, and all were within the normal range.

Selenium in autoimmune thyroiditisGärtner R et al., J Clin Endocrinol Metab 87: 1687–1691, 2002

• Free T4 and T3 as well as TSH values were unchanged in both groups, and all were within the normal range.

• A subgroup analysis of patients with TPOAb greater than 1200 IU/ml revealed a decrease in antibody concentrations in this group to 60% in the selenium group vs. an increase of 10% in the placebo group.

Selenium in autoimmune thyroiditisGärtner R et al., J Clin Endocrinol Metab 87: 1687–1691, 2002

• A decrease in both antibody concentrations below 50 IU/ml was detected in nine patients in the selenium-treated group vs. two patients in the placebo group (P < 0.015).

• Improvement of ultrasound echogenicity was observed in nine patients in the selenium-treated group vs. two patients in the placebo group. These were identical to those patients with a decrease in antibody concentrations below 50 IU/ml, except for one patient in the placebo group.

Selenium in autoimmune thyroiditisMazokopakis EE et al., Thyroid 17: 609-612, 2007

Reduction (%) of the serum anti–thyroid peroxidase (TPO) levels according to continuation (Group A) or discontinuation (Group B) of Se treatment at the second 6 months

STOP seleniumtreatment

Selenium in autoimmune thyroiditisMazokopakis EE et al., Thyroid 17: 609-612, 2007

• Our study showed a significant and constant reduction (21%) of anti-TPO levels in the group which received 12 months of L-selenomethionine treatment.

• There were no significant changes between serum concentrations of TSH, FT3, FT4, and anti-Tg during the study period.

Selenium in autoimmune thyroiditisNacamulli D et al., Clinical Endocrinology 73: 535–539, 2010

Selenium in autoimmune thyroiditisNacamulli D et al., Clinical Endocrinology 73: 535–539, 2010

Selenium in autoimmune thyroiditisNacamulli D et al., Clinical Endocrinology 73: 535–539, 2010

There was no significant difference between the two groups at any follow-up point.

Selenium in autoimmune thyroiditisKaranikas G et al., Thyroid 18: 7-12, 2008

Selenium in autoimmune thyroiditisAnastasilakis AD et al., Int J Clin Pract 66: 378–383, 2012

A prospective, open-label, quasi-randomised study in 86 Hashimoto thyroiditis patients assigned to either selenomethionine 200 µg daily for 3 months (Seme 3, n = 15) or 6 months (Seme 6, n = 46) or placebo (Controls, n = 25).

Anti-TPO levels were not significantly altered by pharmacological doses of Seme for 6 months.

Selenium in autoimmune thyroiditisDuntas LH, J Clin Endocrinol Metab 95: 5180–5188, 2010

Selenium in autoimmune thyroiditisDuntas LH, J Clin Endocrinol Metab 95: 5180–5188, 2010

• Selenium supplementation has positive effects in regions of both selenium deficiency and sufficiency

• This supports to the hypothesis that the result comes about via pharmacological actions, rather than a correction of selenium deficiency

• The lower the selenium levels, the higher the efficacy of treatment

• The higher the amount of anti-TPO, the better the outcome of treatment in terms of reduction of anti-TPO concentration.

Selenium in autoimmune thyroiditisToulis KA, Thyroid 20: 1163-1173, 2010

Selenium in autoimmune thyroiditisToulis KA, Thyroid 20: 1163-1173, 2010

• Although selenium decreases TPOAb titers, the lack of outcomes with direct clinical implications should be underlined

• TPOab titers are considered as a surrogate marker, an intermediate outcome of limited clinical importance in the course of Hashimoto’s thyroiditis, with the exception of pregnancy

• Thus, meaningful clinical outcomes should be demonstrated before Se supplementation can be routinely recommended:

• reducing the progression rate from euthyroidism to subclinical hypothyroidism

• reducing the progression rate from subclinical to overt hypothyroidism

• reducing the need of thyroxine treatment

Selenium and Graves’ ophtalmopathyMarcocci C et al., N Engl J Med 364:1920-31, 2011

Selenium and Graves’ ophtalmopathyMarcocci C et al., N Engl J Med 364:1920-31, 2011

Selenium and Graves’ ophtalmopathyMarcocci C et al., N Engl J Med 364:1920-31, 2011

Selenium and Graves’ ophtalmopathyMarcocci C et al., N Engl J Med 364:1920-31, 2011

Selenium and Graves’ ophtalmopathyMarcocci C et al., N Engl J Med 364:1920-31, 2011

Selenium and Graves’ ophtalmopathyMarcocci C et al., N Engl J Med 364:1920-31, 2011

Selenium in pregnancyNegro R et al., J Clin Endocrinol Metab 92: 1263–1268, 2007

Selenium in pregnancyNegro R et al., J Clin Endocrinol Metab 92: 1263–1268, 2007