Seasonal variations in levels of human thyroid-stimulating hormone and thyroid hormones: a meta-analysis

Kuzmenko, N. V.; Цырлин, В. А.; Плисс, М. Г.; Галагудза, М. М.

doi:10.1080/07420528.2020.1865394

Cited by 36 publications

(22 citation statements)

References 55 publications

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“…Similarly, both the timing and the date of the sample also had an impact on the serum TSH level, as has been noted previously (7,24). What our study adds to the literature, however, is that the above-mentioned factors appear to influence the TSH reference limits and that a large proportion of individuals are potentially at risk of being classed as having subclinical thyroid dysfunction if these factors are not considered.…”

Section: Discussionsupporting

confidence: 75%

Frequency, determinants and costs of thyroid function testing in a laboratory serving a large population

Kennedy

Addison

Tsatlidis

et al. 2022

European Journal of Endocrinology

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Objective: To assess the rationale and frequency of thyroid function testing and to analyse factors that influence serum thyrotropin (TSH) levels. Patients , Design and Main Outcome Measures: Serum TSH levels were evaluated in a hospital laboratory serving a population of 604,000 in 2018. Patients on medications or with conditions affecting thyroid function were excluded. Frequency of thyroid function testing by age and sex was assessed and relationship between serum TSH with potential predictor variables was analysed using ordinary least square regression analysis allowing for potential nonlinearity. Results: Twenty eight percent of the local population had their thyroid function tested at least once in 2018 with significant differences by sex (28.2% women vs 23.4% men) and by age groups, with less than 2% of <16-year-old and more than 50% of >80-year-old people being tested. Most of the symptoms commonly attributed to thyroid dysfunction were not higher in the thyroid dysfunction groups. Serum TSH levels were higher in older people particularly after the age of 60 years, in women (by 0.1 mIU/L), during the early hours of the morning, and in winter and spring seasons. There was remarkable uniformity in the frequency of subclinical thyroid dysfunction, as well as substantial cost savings, if TSH reference intervals were recalculated across sexes, age groups, time-periods and seasons. Conclusions: Serum TSH is frequently tested in the population but is not a good discriminant of symptoms attributed to thyroid dysfunction. Furthermore, considering the influence of factors on TSH reference limits could significantly impact patient care and resource utilisation.

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Section: Discussionsupporting

confidence: 75%

Frequency, determinants and costs of thyroid function testing in a laboratory serving a large population

Kennedy

Addison

Tsatlidis

et al. 2022

European Journal of Endocrinology

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“…The clinical impact of severe iodine deficiency is well-known, but even small differences in iodine status can affect the population distribution of TSH and alter the relationship between TSH and age [ 27 - 31 ]. Serum TSH, and to a lesser extent free T4 and free T3, is also affected by photoperiod and temperature, exhibiting circadian, seasonal and circannual variation [ 32 - 37 ]. The magnitude of these physiological effects can be clinically relevant: for example, the increase in TSH during winter can cause seasonal variation in the diagnosis of subclinical hypothyroidism [ 38 ].…”

Section: Environmental Influencesmentioning

confidence: 99%

Thyroid Function across the Lifespan: Do Age-Related Changes Matter?

Walsh¹

2022

Endocrinol Metab

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Circulating concentrations of thyrotropin (TSH) and thyroxine (T4) are tightly regulated. Each individual has setpoints for TSH and free T4 which are genetically determined, and subject to environmental and epigenetic influence. Pituitary-thyroid axis setpoints are probably established in utero, with maturation of thyroid function continuing until late gestation. From neonatal life (characterized by a surge of TSH and T4 secretion) through childhood and adolescence (when free triiodothyronine levels are higher than in adults), thyroid function tests display complex, dynamic patterns which are sexually dimorphic. In later life, TSH increases with age in healthy older adults without an accompanying fall in free T4, indicating alteration in TSH setpoint. In view of this, and evidence that mild subclinical hypothyroidism in older people has no health impact, a strong case can be made for implementation of age-related TSH reference ranges in adults, as is routine in children.

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“…In the Sahel buck-kids, however, the higher values of circulating TSH may reflect increased production due to reduced responsiveness of the thyroid gland to TSH resulting from heat stressinduced glandular lesions (Nouri et al, 2006) or reduction in glandular secretory activities (Ali et al, 2020). The high values of circulating TSH during the CDS may be a physiological response to cold stress; aimed at increasing production of thyroid hormones to maintain normal body temperature (Habibu et al, 2016a;Kuzmenko et al, 2021). This difference in the seasonal response of young and adult goats may be due to the weak response of buck-kids to the challenge of heat stress, given their physiological immaturity.…”

Section: Discussionmentioning

confidence: 99%

Endogenous and seasonal factors influencing circulating thyrotropin concentration in Red Sokoto and Sahel goats

Habibu¹,

Kawu²,

Aluwong³

et al. 2022

Sokoto J. Vet. Sc.

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Through regulating thyroid physiology, thyrotropin influences the activities of thyroid hormones, including thermogenesis and adaptation to ambient thermal challenges. This study aimed at evaluating the influences of some endogenous factors (breed, sex, age and body mass index; BMI) and season on circulating thyrotropin concentration in Red Sokoto and Sahel goats. A total of 120 goats were sampled, comprising Red Sokoto (n = 20) and Sahel (n = 20) goats in each season during the peak of the cold-dry (CDS), hot-dry (HDS) and rainy (RAS) seasons in a tropical Savannah climate. Results revealed that among Red Sokoto goats, bucks had significantly higher (P<0.05) circulating thyrotropin concentration than does during the HDS, while adults had significantly higher values than kids during the RAS. Significant (P<0.05) breed difference was only observed during the HDS, with the Red Sokoto goats having higher values among adult bucks and doelings but lower values than Sahel goats among buck-kids and adult does. Significant (P<0.05) seasonal variation was observed only in male Sahel goats with buck-kids having lower values during RAS as compared with CDS and HDS, while adult bucks had higher values during the RAS as compared with the HDS. A significant positive correlation (r = 0.29; P<0.001) was observed between thyrotropin concentration and BMI in the overall population. It was concluded that circulating thyrotropin concentration was higher in male and adult goats, and the effects of season and breed were sex and age-dependent. Moreover, the direct relationship between thyrotropin concentration and BMI may reflect the role of thyrotropin in the accumulation of body energy reserve in the savannah goats.

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Seasonal variations in levels of human thyroid-stimulating hormone and thyroid hormones: a meta-analysis

Cited by 36 publications

References 55 publications

Frequency, determinants and costs of thyroid function testing in a laboratory serving a large population

Frequency, determinants and costs of thyroid function testing in a laboratory serving a large population

Thyroid Function across the Lifespan: Do Age-Related Changes Matter?

Endogenous and seasonal factors influencing circulating thyrotropin concentration in Red Sokoto and Sahel goats

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