Establishment of Reference Intervals for Thyroid-Associated Hormones Using refineR Algorithm in Chinese Population at High-Altitude Areas

Abstract

ObjectivesDiagnosis of thyroid disease among individuals dwelling at high altitude remains a challenge. Reference intervals (RIs) for thyroid-associated hormones among Tibetans living at various high altitudes were established to improve diagnosis.MethodsOne thousand two hundred eighty-one subjects were randomly recruited from Nyingchi, Shigatse/Lhasa, and Ali of Tibet. Thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) were measured by the Cobas e601 electrochemiluminescence analyzer. We used multiple linear regression and variance component analysis to assess the effect of sex, age, and altitude on hormones. RIs were established by refineR algorithm and compared with those provided by the manufacturer.ResultsSerum TSH was significantly lower in males than in females, while FT3 and FT4 were higher in males. Both FT3 and FT4 decreased with increasing age. FT3 increased with altitude, while TSH and FT4 were less influenced by altitude. The RI for TSH was 0.764–5.784 μIU/ml, while for FT4, the RIs were 12.36–19.38 pmol/L in females and 14.84–20.18 pmol/L in males. The RIs for FT3 at Nyingchi, Shigatse/Lhasa, and Ali in females were 4.09–4.98, 4.31–5.45, and 4.82–5.58 pmol/L, while in males, the values were 4.82–5.41, 4.88–5.95, and 5.26–6.06 pmol/L, respectively. The obtained RIs for TSH and FT4 were generally higher, while that for FT3 was narrower than the RIs provided by Cobas.ConclusionsSpecific RIs were established for thyroid-associated hormones among Tibetans, which were significantly different from those provided by the manufacturer.

Effects of altitude on thyroid disorders according to Chinese three-rung, ladder-like topography: national cross-sectional study

“…Considering China’s unique ladder-like terrain, we aimed to describe the hyperthyroidism prevalence based on topographic factors. Several studies explored the thyroid status and thyroid disorder prevalence in Tibet (first ladder region) with a small sample size [ 15 , 20 , 36 ]. Furthermore, they only investigated Tibetan regions without comparisons with the other two ladder regions of China with a limited population.…”

“…Thus, diagnosis of thyroid disease among individuals dwelling at high altitudes remains a challenge. Recently, a study investigated thyroid-associated hormones of 1281 participants living in Tibet, the first ladder region of China, and established altitude-specific RI for thyroid-related hormones among residents living in high altitude [ 15 ]. They found that FT3 increased with altitude, while FT4 was less influenced by altitude.…”

“…Endocrine system responses to chronic high-altitude exposure were significantly different from those in sea-level areas or low-altitude plain regions. Researchers investigated the thyroid-associated hormones of 1281 participants living in three different altitude regions of China, and found that free triiodothyronine (FT3) increased with altitude, while free thyroxin (FT4) was less influenced [ 15 ]. Moreover, the hypothalamic-pituitary-thyroid (HPT) axis was reportedly altered in the high-altitude environments, including hypoxic conditions, hypohydration, and nutrition alterations [ 16 – 19 ].…”

Effects of Altitude on Thyroid Disorders according to Chinese Three-Rung, Ladder-like Topography：National Cross- Sectional Study

“…Considering China's unique ladder-like terrain, we aimed to describe the hyperthyroidism prevalence based on topographic factors. Several studies explored the thyroid status and thyroid disorder prevalence in Tibet ( rst ladder) with a small sample size (13,30,31). Furthermore, they only investigated Tibetan regions without comparisons with the other two ladder regions of China with a limited population.…”

“…Recently, a few small, population-based studies explored the association between thyroid status and the rst ladder region of Tibet, although these studies did not compare thyroid status with the other two Chinese ladder regions (13). Furthermore, an Ethiopian study reported that altitude correlated with goiter prevalence, with the peak prevalence observed in the highlands (14).…”