172 EDITORIAL Association of Hypothyroidism with Metabolic Syndrome Aamir Ijaz Correspondence: Prof. Dr. Aamir Ijaz Professor and Consultant Chemical Pathology Rehman Medical Institute, Peshawar E-mail: ijaz_aamir@hotmail.com Received: December 08, 2018 Accepted: December 24, 2018 Metabolic Syndrome (MS) is diagnosed when three out of five cardiometabolic risk factors are present namely hyperglycaemia, low HDL-Cholesterol, high 1 triglycerides, systolic hypertension and obesity. Presence of metabolic syndrome increases the risk of cardiovascular diseases and type 2 diabetes mellitus 2 (T2DM). Other conditions have also been related to metabolic syndromes e.g. cancer, sleep apnea, polycystic ovary syndrome, thyroid disruptions and 3,4 others. There is a worldwide epidemic of MS, Pakistan and some other developing countries are no 4 exception . Hypothyroidism can be overt or sub- clinical. Subclinical-hypothyroidism (SCH) is defined when TSH values are more than 4.0 mIU/L but less than 10 mIU/L with normal thyroid hormones (fT4 5,6 and fT3). The etiological factors for SCH and overt disease are the same with a difference of severity of t h e d i s e a s e , s o S H O i s a l s o ca l l e d ' M i l d Hypothyroidism' as by definition SCH is only a biochemical diagnosis and has nothing to do with the presence or absence of clinical features of thyroid disease. SHO has been shown to be much more 7 common as compared to overt disease. SCH becomes a dilemma for the physician regarding the question of treatment or waiting for the overt 8,9 disease. Amongst many concerned related to hypothyroidism, a propensity for dyslipidaemia is of great concern more so if the patients has other cardiovascular risk factors, too. Khan et al (2018) have recently shown that lipid parameters are adversely affected in hypothyroidism as a continuous function of increasing level of TSH. Lipid changes are found to be more subtle in the subclinical hy p o t hy ro i d g ro u p t h a n ca s e s w i t h ove r t 10 hypothyroidism. Most significant effect has been shown to be on LDL-cholesterol, non-HDL- cholesterol and urine albumin-creatinine ratio. In another recent study it has been shown that he association between MS and hypothyroidism depends on the presence of T2DM. The most important pathophysiological mechanism in T2DM is Insulin Resistance (IR), so it is difficult to ascertain the role of SCH in causation of MS in the presence of 11 T2DM. Various components of metabolic syndrome i.e. high blood pressure, elevated triglycerides level, obesity, and IR have been shown to be closely related to 12,13 subclinical hypothyroidism. It has also been shown that even persons with TSH in the upper reference values (2·5–4·5 mu/l) were more obese, had higher triglycerides, and had an increased 14 likeliness for the metabolic syndrome. Slightly elevated serum TSH levels have also been shown to be associated with an increase in the occurrence of 15 obesity. Another puzzling finding about thyroid hormones and metabolic syndrome is from Wolffenbuttel et al (2017), who have shown that in men, lower FT4 is related to MS but in the highest free Triiodothyronine (FT3) and free thyroxine (FT4) quartiles, there is a 50–80% increased risk of having 16 MS compared to the lowest quartile. This has been confirmed in other recent studies showing MS developing in patient with high FT3 as well as higher 17,18 FT3/FT4 ratio. Insulin resistance is the major biochemical mechanism involved in the causation of MS as well as polycystic ovaries syndrome and non- 19 alcoholic fatty liver disease. Hypothyroidism is associated with elevated markers of insulin resistance such as homeostatic model of insulin 20 21 resistance (HOMA-IR) in adults and children. Despite these known associations, the temporal relationships between subclinical hypothyroidism and assorted cardiovascular risk factors remain largely unexplored and studies are needed to find the chronology of development of components of MS with progression of hypothyroidism. Moreover, TSH should be taken as yardstick for decreasing thyroid function as it is a hormone of the mother gland and the anxiety of the mother gland (pituitary) cannot be compared with the concern of a small child (thyroid) who is totally oblivious of his health Key Words: Hypothyroidism, Metabolic Syndrome, Sub-clinical Hypothyroidism. 173 JIIMC 2018 Vol. 13, No.4 22 condition due to his shear ignorance. TSH alone is a sufficient parameter for the early diagnosis and monitoring of hypothyroidism before one or more components of MS develop. In clinical practice, before starting treatment of dyslipidaemia, obesity or systolic hypertension, especially in a young patient, TSH estimation must be not be forgotten! 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