Effects of 18 months of L-T4 replacement in women with subclinical hypothyroidism.
AffiliationDepartment of Clinical Chemistry, Adelaide and Meath Hospital incorporating the, National Children's Hospital, Dublin 24, Ireland.
*Hormone Replacement Therapy
MetadataShow full item record
CitationClin Endocrinol (Oxf). 2009 Aug;71(2):298-303. Epub 2008 Dec 15.
AbstractCONTEXT: Some of the cardiovascular and renal abnormalities seen in overt hypothyroidism have also been reported in subclinical hypothyroidism (SCH). Short-term L-T4 replacement in SCH improves cardiovascular risk markers and reduces carotid intima-media thickness (CIMT), a surrogate marker of atherosclerosis. The haemodynamic and renal effects of L-T4 replacement in SCH are poorly understood. OBJECTIVES: To compare cardiovascular risk factors and renal variables in women with SCH and normal women. To study the effects of L-T4 replacement in SCH subjects on these variables and on structural and functional changes in common carotid and brachial arteries. DESIGN: Fifty-six women with SCH before and after L-T4 replacement for 18 months and 56 normal women of similar age distribution were studied. Blood Pressure (BP), plasma lipids and homocysteine were measured and renal function evaluated [estimation of glomerular filtration rate (eGFR) using standard equations and measurement of serum Cystatin-C] in women with SCH before and after 18 months of l-T4, and in healthy women. CIMT and endothelial function (using brachial artery ultrasound) were studied before and after L-T4 in a subgroup of women with SCH. RESULTS: Systolic and diastolic BP, total cholesterol, triglyceride, LDL-cholesterol, lipoprotein(a) and homocysteine were greater in SCH (P < 0.05), and following L-T4 replacement decreased (P < 0.05) to levels that no longer differed from normal subjects. Estimated GFR was reduced and serum Cystatin-C increased (P < 0.05) in SCH. These variables also normalized following L-T4. Following L-T4 replacement the carotid artery baseline diameter increased by 7.1% and CIMT decreased by a mean value of 13%, while brachial artery diameter increased basally by 12.5% and following endothelium-dependent vasodilatation by 17.5% (P < 0.05). However, the increment following reactive hyperaemia did not differ before or following L-T4 replacement. CONCLUSION: Normalization of cardiovascular risk factors following L-T4 replacement in SCH potentially explains reduced CIMT. Increased carotid and brachial artery diameters and normalized eGFR indicates a haemodynamic effect of L-T4 replacement, the importance of which requires further investigation.
- Effects of L-thyroxine replacement therapy on carotid intima-media thickness in patients with primary hypothyroidism.
- Authors: Cakal E, Turgut AT, Demirbas B, Ozkaya M, Cakal B, Serter R, Aral Y
- Issue date: 2009 Jun
- Evaluation response and effectiveness of thyroid hormone replacement treatment on lipid profile and function in elderly patients with subclinical hypothyroidism.
- Authors: Arinzon Z, Zuta A, Peisakh A, Feldman J, Berner Y
- Issue date: 2007 Jan-Feb
- Management of overt and subclinical hypothyroidism. Factors influencing L-thyroxine dosage.
- Authors: Rezzónico JN, Pusiol E, Saravi FD, Rezzónico M, Bossa N
- Issue date: 1999
- Changes in brachial-ankle pulse wave velocity in subclinical hypothyroidism during normalization of thyroid function.
- Authors: Nagasaki T, Inaba M, Yamada S, Kumeda Y, Hiura Y, Nishizawa Y
- Issue date: 2007 Sep
- Well-being, health-related quality of life and cardiovascular disease risk profile in women with subclinical thyroid disease - a community-based study.
- Authors: Bell RJ, Rivera-Woll L, Davison SL, Topliss DJ, Donath S, Davis SR
- Issue date: 2007 Apr