Subclinical Hypothyroidism: is it Really Subclinical with Aging?

Abstract

No recent study has focused on clinical features of subclinical hypothyroidism (SCH), especially in older patients. TSH measurement has remarkably evolved these last 20 years and thus reconsideration is needed. In our prospective multicenter study (2012-2014) including 807 subjects aged <60 years (<60y) and 531 subjects ≥60 years (≥60y), we have monitored 11 hypothyroidism-related clinical signs (hCS) together with TSH, FT4, FT3 and anti-thyroperoxidase antibodies values. hCS expression has been compared in patients with SCH vs euthyroidism in each age group. The number of hCS above 60y of age were found to be more elevated in the euthyroid population (1.9 vs 1.6, p<0.01) than in the SCH population (2.3 vs 2.6, p=0.41) while increase in hCS is limited to SCH subjects in the <60y group (p<0.01). The percentage of subjects with at least 3 signs increased with SCH in the <60y group (42.6% vs 25.0%, p<0.01) but not ≥60y (34.4% vs 33.9%, p=0.96). In older individuals, only three hCS could be related to both SCH and a decreased T3/T4-ratio (0.26 vs 0.27, p<0.01), suggesting either a reduced activity of TSH, or an adaptive response with aging. While hCS are clearly associated with SCH in patients <60y, they are not so informative in older subjects. TSH measurements carried out on the basis of hCS need to be interpreted with caution in aged patients. A reassessment of the TSH reference range in older patients is clearly needed and should be associated to more appropriate monitoring of thyroid dysfunction

Association between Subclinical Hypothyroidism and Incident Hypertension in Women: A Systematic Review and Meta-Analysis

“…In a randomized controlled trial for thyroid hormone replacement for untreated older adults with SCH, it was shown that the levothyroxine therapy in the elderly patients diagnosed with SCH provided no symptomatic benefit [ 42 ]. Moreover, it has been shown that elderly patients diagnosed with SCH under current guidelines do not strongly express the clinical signs of hypothyroidism compared to younger SCH patients, and this may further support the inadequacy of using the same guidelines for diagnosing SCH in the elderly population [ 8 ]. Ultimately, we must be cautious when diagnosing and treating SCH in older patients, and a guideline for age-based reference range of TSH is needed.…”

“…Subclinical hypothyroidism (SCH) represents an early form of thyroid dysfunction and is biochemically defined as an elevated TSH (thyroid-stimulating hormone or thyrotropin) level with a normal level of free thyroxine (FT4) within the reference range [ 1 ]. SCH can affect about 1–11% of adults depending on the cohort studied, and such wide variability in its incidence can be attributed to the environmental and ethnic differences as well as the different TSH reference ranges used in each country [ 2 , 3 , 4 , 5 , 6 , 7 , 8 ].…”

TSH Levels in Subclinical Hypothyroidism in the 97.5th Percentile of the Population

“…A number of different researchers have suggested a criterion for treatment but only when there are signs and if the TSH level is >10 mIU/L or >20 mIU/L [14]. In subjects of 60 years and older, some of the signs for Shypo are not as clearly diagnosed as in those under 60 years [32]. TSH values may increase with age, which should lead to a more cautious interpretation of TSH in subjects aged over 60.…”

Efek Dosis Tinggi Potassium Iodate (KIO3) Terhadap Fungsi Tiroid, Thyroid Peroxidase Antibody (TPOAb) dan Berat Badan Pada Tikus Jantan Galur Wistar Hipotiroid

“…Peningkatan kadar TSH pada hipotiroid subklinis menunjukkan telah terjadi hipofungsi tiroid ringan. Hal ini disebabkan karena hubungan antara TSH dengan FT4 disirkulasi bersifat loglinear didasarkan pada mekanisme umpan balik negatif hipotalamus-hipofisis-tiroid (H-P-T) (Hidayat & Susbiantonny, 2018), sehingga FT4 yang berkurang dalam jumlah kecil akan berkorelasi dengan peningkatan logaritmik TSH (Gourmelon et al, 2019). Konsentrasi iodium yang tinggi menyebabkan terjadinya penurunan ringan kadar hormon tiroid dan peningkatan kadar TSH ke batas atas kisaran normal telah dilaporkan pada beberapa penelitian.…”