Thyroid hormones and erythrocyte indices in a cohort of euthyroid older subjects

Abstract Objectives Hypothyroidism is associated with normocytic anaemia. Indeed, a limited number of studies have shown significant associations between free thyroxin (T4) and erythrocyte indices. These studies did not include vitamin B12, folic acid, iron and renal function in the analyses. We the...

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Bibliographic Details
Published in:European journal of internal medicine 2013-04, Vol.24 (3), p.241-244
Main Authors: Schindhelm, Roger K, ten Boekel, Edwin, Heima, Nathalie E, van Schoor, Natasja M, Simsek, Suat
Format: Article
Language:English
Subjects:
Aged
Aging - physiology
Cohort
Erythrocyte Count
Erythrocyte Indices
Female
Haemoglobin
Hematocrit
Humans
Internal Medicine
Linear Models
Longitudinal Studies
Male
Middle Aged
Netherlands - epidemiology
Older subjects
Statistics as Topic
Thyroid Gland - physiology
Thyroid hormones
Thyroid Hormones - blood
Thyrotropin - blood
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Summary:Abstract Objectives Hypothyroidism is associated with normocytic anaemia. Indeed, a limited number of studies have shown significant associations between free thyroxin (T4) and erythrocyte indices. These studies did not include vitamin B12, folic acid, iron and renal function in the analyses. We therefore studied the association between thyroid hormones and erythrocyte indices in a population-based cohort of older euthyroid subjects, with adjustment for major confounding parameters. Design Data, including thyroid hormones and erythrocyte indices, are from the Longitudinal Aging Study Amsterdam (LASA), an ongoing cohort study on predictors and consequences of changes in health in the ageing population in the Netherlands. Multivariable linear regression analyses were applied to study the cross-sectional associations between free T4, thyroid stimulating hormone (TSH) and erythrocyte indices (haemoglobin content, haematocrit, mean cell volume (MCV) and erythrocyte count) in a euthyroid sub-sample. The final models were adjusted for vitamin B12, folic acid, iron levels and renal function. Results In 708 euthyroid older subjects, an increase of 5 pmol/L free T4 was associated with a mean increase of 0.12 mmol/L or 0.19 g/dL of haemoglobin, 0.068 1012 /L erythrocytes and 0.006 L/L haematocrit ( P = 0.007, P = 0.005, P = 0.001, respectively). Free T4 was not significantly associated with MCV ( P > 0.05). TSH appeared not to be associated with any of the erythrocyte indices (all P > 0.05). Conclusions In a cohort of older subjects, free T4, but not TSH, was associated with erythrocyte indices, confirming the role of thyroid hormones in the regulation of erythropoiesis.
ISSN:0953-6205
1879-0828
DOI:10.1016/j.ejim.2012.12.004