Circannual Rhythm of Plasma Thyrotropin in Middle-Aged and Old Euthyroid Subjects

Simoni, Manuela; Velardo, A; Montanini, V.; Fustini, Mattia; Seghedoni, S.; Marrama, P

doi:10.1159/000181506

Cited by 24 publications

(26 citation statements)

References 11 publications

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“…Using an improved method, in a large sample of young, middle-aged, and old individuals, a statistically significant circannual rhythm of plasma TSH levels was observed only in middle-aged and old individuals, regardless of sex. TSH peaked in December, and this monthly value was 30% higher than summer values (Simoni et al, 1990). A circannual rhythm in TSH values, with an acrophase in December, was observed in Belgian subjects (Maes et al, 1997).…”

Section: Discussionmentioning

confidence: 76%

“…During winter, hypothyroid patients who consume a fixed dose of levothyroxine showed an increase in the response of serum TSH to thyrotropin-releasing hormone (Hamada et al, 1984;Reed, 1995). A large study of 8310 young, middle-aged, and old adults revealed a significant circannual TSH rhythm, with a TSH peak in December among >41-yrold individuals, but no significant rhythm among younger subjects in Italy (Simoni et al, 1990). Also, TSH values have been shown to differ by 29% in Belgian individuals (mean age of 39 yrs) between spring (minimum value) and winter (maximum value), with a peak value in December (Maes et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

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Seasonal Variation of Neonatal Transient Hyperthyrotropinemia in Tehran Province, 1998–2005

Ordookhani

Padyab

Goldasteh

et al. 2010

Chronobiology International

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Seasonal aggregation and the monthly rate of neonatal transient hyperthyrotropinemia (THT) were assessed. From November 1998 to April 2005, neonates of gestational age ≥37 wks, birth weight 2500-4000 g, birth length 45-55 cm, and 1st min Apgar score >3, who had thyrotropin (TSH) ≥20 mU/L in their cord dried-blood specimen, but without congenital hypothyroidism, were enrolled in the study. The recall rate equals the rate of THT occurrence in this study. Of 47,945 neonates, 555 had THT (recall rate: 1.2%). The aggregated seasonal recall rate (recall for further assessment to rule out congenital hypothyroidism) was significantly higher in winter (January, February, and March) than the other seasons (p < .0001). Winter had higher recall rate in each year as compared to other seasons, but the overall rate of recalls decreased in 2001 and 2002. Excluding the first 6 months (due to erratic variations), the remaining 72 months revealed a relatively sinusoidal pattern in monthly recall rates; indeed, there was an initial 11-month high recall rates (1.7%), followed by a 33-month decrease (0.7%), a 19-month increase (1.9%), and a final 9-month decrease (0.8%). The recall rate of each of these time intervals was significantly different from that of the next time interval (p < .0001). The monthly recall rates were best fitted to cubic curve estimation and then autoregressive integrated moving average (ARIMA) (0, 1, 1) models. THT occurs significantly more in winter than in other seasons, and this suggests a possible role for time-varying factor(s) contributing to its seasonal preponderance.

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Section: Discussionmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Seasonal Variation of Neonatal Transient Hyperthyrotropinemia in Tehran Province, 1998–2005

Ordookhani

Padyab

Goldasteh

et al. 2010

Chronobiology International

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“…In older Italian subjects, elevated TSH levels were observed in winter, but the relationship between TSH and environmental temperature was not significant, indicating that temperature is not important in determining TSH levels (Simoni et al 1990). In a Belgian study, serum TSH was significantly elevated in April, June and December and serum total T 3 in December (Maes et al 1997).…”

Section: Discussionmentioning

confidence: 99%

“…In hypothyroid subjects, lower serum T 4 levels and higher serum TSH levels and TSH responses to TRH were found in winter rather than in summer (Konno & Morikawa 1982). In another study, involving large populations, the serum TSH levels of young, middle-aged and old Italian subjects were at their highest in December in the middleand old-age classes (Simoni et al 1990), but no seasonal changes were seen in younger subjects (Pasquali et al 1984, Simoni et al 1990). In a recent study both serum TSH and free T 3 were highest in winter in healthy Belgian subjects (Maes et al 1997).…”

Section: Introductionmentioning

confidence: 90%

The pituitary-thyroid axis in healthy men living under subarctic climatological conditions

Hassi

Sikkilä²,

Ruokonen³

et al. 2001

Journal of Endocrinology

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In order to evaluate the effects of climatic factors on the secretion of thyroid hormones and TSH in a high latitude population, we have taken serum and urine samples from 20 healthy men from northern Finland (67 -68 N) every 2 months for a period of 14 months. Serum free triiodothyronine (T 3 ) levels were lower in February than in August (3·9 vs 4·4 pmol/l, P<0·05) and TSH levels were higher in December than during other months (2·1 vs 1·5-1·7 mU/l, P<0·01). Serum total and free thyroxine (T 4 ), total T 3 and reverse T 3 levels and urinary T 4 levels were unchanged. Urinary T 3 levels were significantly higher in winter than in summer. Serum free T 3 correlated highly significantly with the outdoor temperature integrated backwards weekly for 7-56 days (r=0·26 for 1-56 days) from the day when the blood samples were taken. Serum TSH did not show any significant correlation with the thyroid hormones or with the integrated temperature of the previous days, but it did show an inverse and significant correlation (r= 0·31) with the ambient luminosity integrated backwards for 7 days from the day when the blood sample was taken. The gradually increasing correlation between outdoor temperatures and serum free T 3 suggests that the disposal of thyroid hormones is accelerated in winter, leading to low serum free T 3 levels and a high urinary free T 3 excretion. Since there was no correlation between thyroid hormones and serum TSH, the feedback mechanism between TSH and thyroid hormones may not be the only contributing factor, and other factors such as ambient luminosity may at least partly determine serum TSH in these conditions. Also urinary free T 3 appears to be a novel and non-invasive indicator for thyroid physiology.

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“…Thus, it would appear that in addition to reduced secretion, the aging process involves alterations of central mechanisms controlling the temporal organization of hormone release (184). Interestingly, a significant circannual rhythm of serum TSH with acrophase in December was documented in middle-aged, but not in young, normal subjects (186).…”

Section: Serum Thyroid Hormone Concentration and Transportmentioning

confidence: 98%

The Aging Thyroid

et al. 1995

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Circannual Rhythm of Plasma Thyrotropin in Middle-Aged and Old Euthyroid Subjects

Cited by 24 publications

References 11 publications

Seasonal Variation of Neonatal Transient Hyperthyrotropinemia in Tehran Province, 1998–2005

Seasonal Variation of Neonatal Transient Hyperthyrotropinemia in Tehran Province, 1998–2005

The pituitary-thyroid axis in healthy men living under subarctic climatological conditions

The Aging Thyroid

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