The reference intervals of thyroid stimulating hormone in healthy individuals with normal levels of serum free thyroxine and without sonographic pathologies

Abstract

Studies suggest that determination of the TSH reference intervals may differ due to environmental influences or due to age, gender, and race. It is suggested that the lower limit of normal TSH for the adult Turkish population would be 0.38 mIU/L and the upper limit similar to the traditional value of 4.2 mIU/L. If each clinician uses their population-specific reference interval for TSH, thyroid function abnormalities can be accurately estimated.

Effects of thyrotrophin, thyroid hormones and thyroid antibodies on metabolic parameters in a euthyroid population with obesity

“…In our study, the median TSH level in the antibody‐negative group was 1·8 μIU/ml. This value was higher than that found in another study from Turkey, with 408 normal‐weight participants aged ≥18 who were negative for thyroid antibodies, which reported a median TSH level of 1·4 μIU/ml …”

“…This value was higher than that found in another study from Turkey, with 408 normal-weight participants aged ≥18 who were negative for thyroid antibodies, which reported a median TSH level of 1Á4 lIU/ml. 32 The association between thyroid function and metabolic parameters is complex. Thyroid hormones act on the liver, white adipose tissue, skeletal muscle and pancreas to influence plasma glucose levels, insulin sensitivity and carbohydrate metabolism.…”

Association of TSH Elevation with All-Cause Mortality in Elderly Patients with Chronic Kidney Disease

“…A recent epidemiological study found a significant relationship between elevated thyroid-stimulating hormone (TSH) level and the development of CKD in elderly persons [4]. Other studies have shown that TSH level increases with aging in the general population [5, 6, 7, 8, 9], and hypothyroidism is prevalent among CKD patients [10, 11, 12]. However, the relationship between mild thyroid dysfunction and mortality is unclear.…”

TSH cut off point based on depression in hypothyroid patients

“…In fact, various studies have introduced different population-based cut-off points in individuals without any clinical or serological evidences of thyroid disease. TSH cut-off points were determined to be 3.4, 0.6–3.7, 0.2–4.6, 0.38–4.2, 0.4–3.4, 0.3–5.1, 1.3–3.1, 0.39–4.2, and 0.7–7 mU/L in studies by Zarcovic [ 25 ], Chan in Hong Kong (on Chinese cases) [ 26 ], Rosario in Brazil (on aged subjects) [ 27 ], Kutluturk in Turkey [ 28 ], Langen in Finland [ 29 ], Sriphrapradang in Thailand [ 30 ], Marwaha in adult Indians [ 31 ], Yoshihara in Japan [ 32 ], and Kim in Korea [ 33 ], respectively. Nevertheless, Haddad in Texas could not detect a TSH cut-off point and found that a lower TSH level could lead to the relief of fatigue [ 34 ].…”

“…Nevertheless, Haddad in Texas could not detect a TSH cut-off point and found that a lower TSH level could lead to the relief of fatigue [ 34 ]. Kutluturk recommended that a population-specific TSH level should be detected [ 28 ]. Marwaha concluded that a TSH cut-off point should be age- and gender-specific [ 31 ].…”