Planktonic events may cause polymictic-dimictic regime shifts in temperate lakes

Water transparency affects the thermal structure of lakes, and within certain lake depth ranges, it can determine whether a lake mixes regularly (polymictic regime) or stratifies continuously (dimictic regime) from spring through summer. Phytoplankton biomass can influence transparency but the effect of its seasonal pattern on stratification is unknown. Therefore we analysed long term field data from two lakes of similar depth, transparency and climate but one polymictic and one dimictic, and simulated a conceptual lake with a hydrodynamic model. Transparency in the study lakes was typically low during spring and summer blooms and high in between during the clear water phase (CWP), caused when zooplankton graze the spring bloom. The effect of variability of transparency on thermal structure was stronger at intermediate transparency and stronger during a critical window in spring when the rate of lake warming is highest. Whereas the spring bloom strengthened stratification in spring, the CWP weakened it in summer. The presence or absence of the CWP influenced stratification duration and under some conditions determined the mixing regime. Therefore seasonal plankton dynamics, including biotic interactions that suppress the CWP, can influence lake temperatures, stratification duration, and potentially also the mixing regime

Canadian Endocrinologists\u27 Perspectives on Treatment With Thyroid Hormone Substitutions in Euthyroid and Hypothyroid Patients: A 2023 THESIS Questionnaire Survey

\ua9 2025 The Author(s). Clinical Endocrinology published by John Wiley & Sons Ltd. Objective: The practice of treating hypothyroid and euthyroid patients with thyroid hormones varies between countries, as observed in the recent surveys of European thyroid experts, THESIS. As part of the THESIS initiative, we investigated Canadian endocrinologists′ perspectives on this topic, focusing on combination therapy with either liothyronine (LT3) plus levothyroxine (LT4) or desiccated thyroid extract (DTE). Design: Members of the Canadian Society of Endocrinology and Metabolism (CSEM) were invited to participate in an anonymous online survey. Results: Out of 348 eligible CSEM members, 68 (19.5%) respondents were included in the analysis. All respondents used LT4 as the first-line treatment for hypothyroid patients. Many respondents (64.7%) would consider LT4 + LT3 for patients on LT4 with persistent symptoms, whereas fewer would consider DTE (16.2%). Most respondents attributed persistent symptoms in LT4-treated patients to psychosocial factors, comorbidities, or unrealistic expectations. Approximately half of the respondents stated that thyroid hormone therapy is never indicated for euthyroid patients. The remaining respondents considered thyroid hormones for euthyroid women with infertility and high thyroid antibody levels (36.8%), depression (13.2%), and growing goiter (7.4%). Conclusions: Following current guidelines, LT4 tablet is the preferred treatment for hypothyroidism. Most respondents would consider triiodothyronine-containing therapy for patients with persistent symptoms, preferring LT4 + LT3 over DTE. The number of endocrinologists considering combination therapy for hypothyroid patients in Canada was higher than in Europe. Finally, at variance with current guidelines, a fraction of the respondents would consider thyroid hormones in patients with non-thyroidal conditions

The effect on behavior and bone mineral density of individualized bone mineral density feedback and educational interventions in premenopausal women: a randomized controlled trial [NCT00273260]

BACKGROUND: Limited information is available on ways to influence osteoporosis risk in premenopausal women. This study tested four hypotheses regarding the effects of individualized bone density (BMD) feedback and different educational interventions on osteoporosis preventive behavior and BMD in pre-menopausal women, namely: that women are more likely to change calcium intake and physical activity if their BMD is low; that group education will be more efficacious at changing behavior than an information leaflet; that BMD feedback and group education have independent effects on behavior and BMD; and, that women who improve their physical activity or calcium intake will have a change in bone mass over 2 years that is better than those who do not alter their behavior. METHODS: We performed a 2-year randomized controlled trial of BMD feedback according to T-score and either an osteoporosis information leaflet or small group education in a population-based random sample of 470 healthy women aged 25–44 years (response rate 64%). Main outcome measures were dietary calcium intake, calcium supplement use, smoking behavior, physical activity, endurance fitness, lower limb strength and BMD. We used paired t-tests, one-way ANOVA and linear regression techniques for data analysis. RESULTS: Women who had feedback of low BMD had a greater increase in femoral neck BMD than those with normal BMD (1.6% p.a. vs. 0.7% p.a., p = 0.0001), but there was no difference in lumbar spine BMD change between these groups (0.1% p.a. vs. 0.08% p.a., p = 0.9). Both educational interventions had similar increases in femoral neck BMD (Leaflet = +1.0% p.a., Osteoporosis self-management course = + 1.3% p.a., p = 0.4). Femoral neck BMD change was only significantly associated with starting calcium supplements (1.3 % p.a, 95%CI +0.49, +2.17) and persistent self-reported change in physical activity levels (0.7% p.a., 95%CI +0.22, +1.22). CONCLUSION: Individualized BMD feedback combined with a minimal educational intervention is effective at increasing hip but not spine bone density in premenopausal women. The changes in behavior through which this was mediated are potentially important in the prevention of other diseases, thus measuring BMD at a young age may have substantial public health benefits, particularly if these changes are sustained

Treatment of Obesity with Thyroid hormones in Europe. Data from the THESIS* Collaboration

\ua9 The Author(s) 2024.Purpose: The use of thyroid hormones (TH) to treat obesity is unsupported by evidence as reflected in international guidelines. We explored views about this practice, and associations with respondent characteristics among European thyroid specialists. Methods: Specialists from 28 countries were invited to a survey via professional organisations. The relevant question was whether “Thyroid hormones may be indicated in biochemically euthyroid patients with obesity resistant to lifestyle interventions”. Results: Of 17,232 invitations 5695 responses were received (33% valid response rate; 65% women; 90% endocrinologists). Of these, 290 (5.1%) stated that TH may be indicated as treatment for obesity in euthyroid patients. This view was commoner among non-endocrinologists (8.7% vs. 4.7%, p < 0.01), private practice (6.5% vs. 4.5%, p < 0.01), and varied geographically (Eastern Europe, 7.3%; Southern Europe, 4.8%; Western Europe, 2.7%; and Northern Europe, 2.5%). Respondents from Northern and Western Europe were less likely to use TH than those from Eastern Europe (p < 0.01). Gross national income (GNI) correlated inversely with this view (OR 0.97, CI: 0.96–0.97; p < 0.001). Having national guidelines on hypothyroidism correlated negatively with treating obesity with TH (OR 0.71, CI: 0.55–0.91). Conclusions: Despite the lack of evidence, and contrary to guidelines’ recommendations, about 5% of respondents stated that TH may be indicated as a treatment for obesity in euthyroid patients resistant to life-style interventions. This opinion was associated with (i) respondent characteristics: being non-endocrinologist, working in private practice, treating a small number of hypothyroid patients annually and (ii) national characteristics: prevalence of obesity, Eastern Europe, low GNI and lack of national hypothyroidism guidelines

Characteristics of specialists treating hypothyroid patients: the “THESIS” collaborative

Copyright \ua9 2023 Žarković, Attanasio, Nagy, Negro, Papini, Perros, Cohen, Akarsu, Alevizaki, Ayvaz, Bednarczuk, Berta, Bodor, Borissova, Boyanov, Buffet, Burlacu, Ćirić, D\uedez, Dobnig, Fadeyev, Field, Fliers, Fr\uf8lich, F\ufchrer, Galofr\ue9, Hakala, Jiskra, Kopp, Krebs, Kršek, Kužma, Lantz, Laz\ufarov\ue1, Leenhardt, Luchytskiy, McGowan, Melo, Metso, Moran, Morgunova, Mykola, Beleslin, Niculescu, Perić, Planck, Poiana, Puga, Robenshtok, Rosselet, Ruchala, Riis, Shepelkevich, Unuane, Vardarli, Visser, Vrionidou, Younes, Yurenya and Heged\ufcs.Introduction: Thyroid specialists influence how hypothyroid patients are treated, including patients managed in primary care. Given that physician characteristics influence patient care, this study aimed to explore thyroid specialist profiles and associations with geo-economic factors. Methods: Thyroid specialists from 28 countries were invited to respond to a questionnaire, Treatment of Hypothyroidism in Europe by Specialists: an International Survey (THESIS). Geographic regions were defined according to the United Nations Statistics Division. The national economic status was estimated using World Bank data on the gross national income per capita (GNI per capita). Results: 5,695 valid responses were received (response rate 33\ub70%). The mean age was 49 years, and 65\ub70% were female. The proportion of female respondents was lowest in Northern (45\ub76%) and highest in Eastern Europe (77\ub72%) (p <0\ub7001). Respondent work volume, university affiliation and private practice differed significantly between countries (p<0\ub7001). Age and GNI per capita were correlated inversely with the proportion of female respondents (p<0\ub701). GNI per capita was inversely related to the proportion of respondents working exclusively in private practice (p<0\ub7011) and the proportion of respondents who treated >100 patients annually (p<0\ub701). Discussion: THESIS has demonstrated differences in characteristics of thyroid specialists at national and regional levels, strongly associated with GNI per capita. Hypothyroid patients in middle-income countries are more likely to encounter female thyroid specialists working in private practice, with a high workload, compared to high-income countries. Whether these differences influence the quality of care and patient satisfaction is unknown, but merits further study

The use of thyroid hormones in the treatment of euthyroid patients with treatment-resistant depression. Data from a survey of 5695 European national endocrine professional organization members

Copyright \ua9 2025 Ludgate, McGowan, Moran, Attanasio, Žarković, Nagy, Negro, Papini, Adler Cohen, Akarsu, Alevizaki, Ayvaz, Bednarczuk, Beleslin, Berta, Bodor, Borissova, Boyanov, Buffet, Burlacu, Ćirić, D\uedez, Dobnig, Fadeyev, Field, Fliers, F\ufchrer-Sakel, Galofr\ue9, Hakala, Jiskra, Kopp, Krebs, Kršek, Kužma, Laz\ufarov\ue1, Leenhardt, Luchytskiy, Melo, Metso, Morgunova, Niculescu, Perić, Planck, Poiana, Marques Puga, Robenshtok, Rosselet, Ruchala, Riis, Shepelkevich, Tronko, Fr\uf8lich, Unuane, Vardarli, Visser, Vryonidou, Younes, Yurenya, Perros and Heged\ufcs.Purpose: Treatment-resistant depression (TRD) is most commonly defined as depression that has not responded to two different pharmacological agents used for an adequate period of time. We explored the views of European specialists via survey, regarding the use of thyroid hormone (TH) in euthyroid patients with TRD as part of ‘Treatment of Hypothyroidism in Europe by Specialists: An International Survey’ (THESIS). Methods: The question “Thyroid hormones may be indicated in biochemically euthyroid patients with treatment resistant depression” was posed to specialists from 28 countries. Results: 5695 valid responses were received following 17,232 invitations (33.0% response rate; 65% female, 90% endocrinologists). 348 (6.1%) stated that TH may be indicated in biochemically euthyroid patients with TRD. This view was more common in males (p<0.01), respondents who saw ≥100 patients with hypothyroidism per year (p<0.01), respondents who worked in private practice (p=0.05) and respondents who were not members of international specialist associations (p=0.05). Geographical variation existed with respondents in Eastern Europe significantly more likely to use TH in TRD (p<0.01). Linear regression showed a statistically significant reduction in the use of TH for TRD with increasing gross national income (F-statistic=7.35, CI -0.15 - -0.02, p=0.01). TH in TRD was recommended in psychiatry guidelines but not endocrinology guidelines. Conclusion: While there is limited evidence for their use, over 6% of respondents stated that TH may be indicated in TRD. Due to the risk of iatrogenic thyrotoxicosis and increased morbidity the use of TH should be addressed in relevant endocrinology guidelines and consensus should be reached between specialties