Serum microRNA profiles in athyroid patients on and off levothyroxine therapy

BackgroundLevothyroxine replacement treatment in hypothyroidism is unable to restore physiological thyroxine and triiodothyronine concentrations in serum and tissues completely. Normal serum thyroid stimulating hormone (TSH) concentrations reflect only pituitary euthyroidism and, therefore, novel biomarkers representing tissue-specific thyroid state are needed. MicroRNAs (miRNAs), small non-coding regulatory RNAs, exhibit tissue-specific expression patterns and can be detectable in serum. Previous studies have demonstrated differential expression of (precursors of) miRNAs in tissues under the influence of thyroid hormone.ObjectiveTo study if serum miRNA profiles are changed in different thyroid states.Design and methodsWe studied 13 athyroid patients (6 males) during TSH suppressive therapy and after 4 weeks of thyroid hormone withdrawal. A magnetic bead capture system was used to isolate 384 defined miRNAs from serum. Subsequently, the TaqMan Array Card 3.0 platform was used for profiling after individual target amplification.ResultsMean age of the subjects was 44.0 years (range 20-61 years). Median TSH levels were 88.9 mU/I during levothyroxine withdrawal and 0.006 mU/I during LT4 treatment with a median dosage of 2.1 fag/kg. After normalization to allow inter-sample analysis, a paired analysis did not demonstrate a significant difference in expression of any of the 384 miRNAs analyzed on and off LT4 treatment.ConclusionAlthough we previously showed an up-regulation of pri-miRNAs 133b and 206 in hypothyroid state in skeletal muscle, the present study does not supply evidence that thyroid state also affects serum miRNAs in humans

Serum microRNA profiles in athyroid patients on and off levothyroxine therapy

Background Levothyroxine replacement treatment in hypothyroidism is unable to restore physiological thyroxine and triiodothyronine concentrations in serum and tissues completely. Normal serum thyroid stimulating hormone (TSH) concentrations reflect only pituitary euthyroidism and, therefore, novel biomarkers representing tissue-specific thyroid state are needed. MicroRNAs (miRNAs), small non-coding regulatory RNAs, exhibit tissue-specific expression patterns and can be detectable in serum. Previous studies have demonstrated differential expression of (precursors of) miRNAs in tissues under the influence of thyroid hormone. Objective To study if serum miRNA profiles are changed in different thyroid states. Design and methods We studied 13 athyroid patients (6 males) during TSH suppressive therapy and after 4 weeks of thyroid hormone withdrawal. A magnetic bead capture system was used to isolate 384 defined miRNAs from serum. Subsequently, the TaqMan Array Card 3.0 platform was used for profiling after individual target amplification. Results Mean age of the subjects was 44.0 years (range 20–61 years). Median TSH levels were 88.9 mU/l during levothyroxine withdrawal and 0.006 mU/l during LT4 treatment with a median dosage of 2.1 μg/kg. After normalization to allow inter-sample analysis, a paired analysis did not demonstrate a significant difference in expression of any of the 384 miRNAs analyzed on and off LT4 treatment

Selenium status is positively associated with bone mineral density in healthy aging European men

Objective It is still a matter of debate if subtle changes in selenium (Se) status affect thyroid function tests (TFTs) and bone mineral density (BMD). This is particularly relevant for the elderly, whose nutritional status is more vulnerable. Design and Methods We investigated Se status in a cohort of 387 healthy elderly men (median age 77 yrs; inter quartile range 75-80 yrs) in relation to TFTs and BMD. Se status was determined by measuring both plasma selenoprotein P (SePP) and Se. Results The overall Se status in our population was low normal with only 0.5% (2/387) of subjects meeting the criteria for Se deficiency. SePP and Se levels were not associated with thyroid stimulating hormone (TSH), free thyroxine (FT4), thyroxine (T4), triiodothyronine (T3) or reverse triiodothyronine (rT3) levels. The T3/T4 and T3/rT3 ratios, reflecting peripheral metabolism of thyroid hormone, were not associated with Se status either. SePP and Se were positively associated with total BMD and femoral trochanter BMD. Se, but not SePP, was positively associated with femoral neck and ward's BMD. Multivariate linear analyses showed that these associations remain statistically significant in a model including TSH, FT4, body mass index, physical performance score, age, smoking, diabetes mellitus and number of medication use. Conclusion Our study demonstrates that Se status, within the normal European marginally supplied range, is positively associated with BMD in healthy aging men, independent of thyroid function. Thyroid function tests appear unaffected by Se status in this population

Selenium status and association with bone mineral density.

<p>Selenium status and association with bone mineral density.</p

Associations between selenium status and thyroid function tests.

<p>Associations between selenium status and thyroid function tests.</p

Baseline characteristics.

<p>Baseline characteristics.</p

Heat map showing the Cq values of all detectable MiRNAs (n = 135) in the different thyroid states.

<p>Clustering did not group the samples according to thyroid state.</p