Increased Serum Chitotriosidase Activity following Restoration of Euthyroidism in Patients with Subclinical Hypothyroidism

• Published in: Internal Medicine Vol. 47; no. 14; pp. 1309 - 1314
• Main Authors: Erdal, Muhammed, Sahin, Mustafa, Saglam, Kenan, Hasimi, Adnan, Uckaya, Gokhan, Yarpuz, Mustafa Yalcin, Taslipinar, Abdullah, Gharib, Hossein, Kutlu, Mustafa
• Format: Journal Article
• Language: English
• Published: Japan The Japanese Society of Internal Medicine 2008
• Subjects: Adult; Biomarkers - blood; cardiovascular risk factors; Case-Control Studies; chitotriosidase; Coronary Artery Disease - blood; Female; Hexosaminidases - blood; Hexosaminidases - drug effects; highly sensitive CRP; homocysteine; Hormone Replacement Therapy; Humans; Hypothyroidism - drug therapy; Hypothyroidism - enzymology; levothyroxine replacement; Male; Middle Aged; Risk Factors; subclinical hypothyroidism; Thyroxine - adverse effects
• ISSN: 0918-2918; 1349-7235
• DOI: 10.2169/internalmedicine.47.1013

Objective Whether to treat subclinical hypothyroidism (SH) remains controversial. Serum chitotriosidase activity, a marker of activated macrophages, predicts new cardiovascular events. Chitotriosidase activity (ChT) is a new cardiovascular risk marker and is independent of C-reactive protein. The purpose of this study was to determine ChT levels in SH and to examine the effect of levothyroxine replacement on ChT. Subjects and Methods A cohort of 60 patients with subclinical hypothyroidism and 62 healthy controls were enrolled in this study. Serum total and LDL cholesterol, total homocysteine (t-Hyc), highly sensitive C-reactive protein (hsCRP) levels and serum ChT in patients with subclinical hypothyroidism at baseline and after achieving euthyroid state by levothyroxine were assessed. Results Pretreatment levels of TSH (10.06±5.09 vs. 2.08±0.95 mIU/L, p<0.05), and free T4 (0.94±0.21 vs. 1.35±0.26 ng/dl, p<0.05) were significantly higher than controls while total cholesterol, LDL cholesterol, t-Hyc, ChT and hsCRP levels were not different. ChT levels significantly increased after replacement therapy (137.2±14.18 vs. 156.88±13.10 nmol/mL/h, p<0.05). T-Hyc and hsCRP levels were not significantly different after treatment with levothyroxine therapy even in this subgroup of patients. None of the other biochemical risk factors improved after euthyroidism in patients with SH with average dose of 85±30 μg/day when compared to pretreatment levels. Conclusion We conclude that clinical management of subclinical hypothyroidism does not decrease the serum hsCRP or t-Hyc levels but does increase the serum ChT levels. The clinical significance of this increament should be studied in further studies.