Mild subclinical hypothyroidism may normalise without treatment among older adults

With age, the prevalence of subclinical hypothyroidism rises. However, incidence and determinants of spontaneous normalization remain largely unknown.

A study was done to investigate incidence and determinants of spontaneous normalization of thyroid-stimulating hormone (TSH) levels in older adults with subclinical hypothyroidism.

Pooled data were used from the (i) pre-trial population, and (ii) in-trial placebo group from two randomized, double-blind, placebo-controlled trials (TRUST and IEMO thyroid 80-plus thyroid trial).

Community-dwelling 65 + adults with subclinical hypothyroidism from the Netherlands, Switzerland, Ireland, and the United Kingdom.

The pre-trial population (N = 2335) consisted of older adults with biochemical subclinical hypothyroidism, defined as ≥1 elevated TSH measurement (≥4.60 mIU/L) and a free thyroxine (fT4) within the laboratory-specific reference range. Individuals with persistent subclinical hypothyroidism, defined as ≥2 elevated TSH measurements ≥3 months apart, were randomized to levothyroxine/placebo, of which the in-trial placebo group (N = 361) was included.

Incidence of spontaneous normalization of TSH levels and associations between participant characteristics and normalization.

Results

In the pre-trial phase, TSH levels normalized in 60.8% of participants in a median follow-up of one year. In the in-trial phase, levels normalized in 39.9% of participants after one year follow-up. Younger age, female sex, lower initial TSH level, higher initial fT4 level, absence of thyroid peroxidase antibodies, and a follow-up measurement in summer were independent determinants for normalization.

Since TSH levels spontaneously normalized in a large proportion of older adults with subclinical hypothyroidism (also after confirmation by repeat measurement), a third measurement may be recommended before considering treatment.

Reference:

Evie van der Spoel, Nicolien A van Vliet, Rosalinde K E Poortvliet, Robert S Du Puy, Wendy P J den Elzen, Terence J Quinn, David J Stott, Naveed Sattar, Patricia M Kearney, Manuel R Blum, Heba Alwan, Nicolas Rodondi, Tinh-Hai Collet, Rudi G J Westendorp, Bart E Ballieux, J Wouter Jukema, Olaf M Dekkers, Jacobijn Gussekloo, Simon P Mooijaart, Diana van Heemst, Incidence and determinants of spontaneous normalization of subclinical hypothyroidism in older adults, The Journal of Clinical Endocrinology & Metabolism, 2023;, dgad623, https://doi.org/10.1210/clinem/dgad623

Keywords:

Mild, subclinical, hypothyroidism, may, normalise, without, treatment, among, older, adults, The Journal of Clinical Endocrinology & Metabolism, Evie van der Spoel, Nicolien A van Vliet, Rosalinde K E Poortvliet, Robert S Du Puy, Wendy P J den Elzen, Terence J Quinn, David J Stott, Naveed Sattar, Patricia M Kearney, Manuel R Blum, Heba Alwan, Nicolas Rodondi, Tinh-Hai Collet, Rudi G J Westendorp, Bart E Ballieux, J Wouter Jukema