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Vega RB, Whytock KL, Gassenhuber J, Goebel B, Tillner J, Agueusop I, Truax AD, Yu G, Carnero E, Kapoor N, Gardell S, Sparks LM, Smith SR. A Metabolomic Signature of Glucagon Action in Healthy Individuals With Overweight/Obesity. J Endocr Soc 2021; 5:bvab118. [PMID: 34337278 PMCID: PMC8317630 DOI: 10.1210/jendso/bvab118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Indexed: 11/19/2022] Open
Abstract
Context Glucagon is produced and released from the pancreatic alpha-cell to regulate glucose levels during periods of fasting. The main target for glucagon action is the liver, where it activates gluconeogenesis and glycogen breakdown; however, glucagon is postulated to have other roles within the body. Objective We sought to identify the circulating metabolites that would serve as markers of glucagon action in humans. Methods In this study (NCT03139305), we performed a continuous 72-hour glucagon infusion in healthy individuals with overweight/obesity. Participants were randomized to receive glucagon 12.5 ng/kg/min (GCG 12.5), glucagon 25 ng/kg/min (GCG 25), or a placebo control. A comprehensive metabolomics analysis was then performed from plasma isolated at several time points during the infusion to identify markers of glucagon activity. Results Glucagon (GCG 12.5 and GCG 25) resulted in significant changes in the plasma metabolome as soon as 4 hours following infusion. Pathways involved in amino acid metabolism were among the most affected. Rapid and sustained reduction of a broad panel of amino acids was observed. Additionally, time-dependent changes in free fatty acids and diacylglycerol and triglyceride species were observed. Conclusion These results define a distinct signature of glucagon action that is broader than the known changes in glucose levels. In particular, the robust changes in amino acid levels may prove useful to monitor changes induced by glucagon in the context of additional glucagon-like peptide-1 or gastric inhibitory polypeptide treatment, as these agents also elicit changes in glucose levels.
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Affiliation(s)
- Rick B Vega
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
| | - Katie L Whytock
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
| | | | | | | | | | | | - Gongxin Yu
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
| | - Elvis Carnero
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
| | - Nidhi Kapoor
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
| | - Stephen Gardell
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
| | - Lauren M Sparks
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
| | - Steven R Smith
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
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Abstract
Background: The basis for the treatment of hypothyroidism with levothyroxine (LT4) is that humans activate T4 to triiodothyronine (T3). Thus, while normalizing serum thyrotropin (TSH), LT4 doses should also restore the body's reservoir of T3. However, there is evidence that T3 is not fully restored in LT4-treated patients. Summary: For patients who remain symptomatic on LT4 therapy, clinical guidelines recommend, on a trial basis, therapy with LT4+LT3. Reducing the LT4 dose by 25 mcg/day and adding 2.5-7.5 mcg liothyronine (LT3) once or twice a day is an appropriate starting point. Transient episodes of hypertriiodothyroninemia with these doses of LT4 and LT3 are unlikely to go above the reference range and have not been associated with adverse drug reactions. Trials following almost a 1000 patients for almost 1 year indicate that similar to LT4, therapy with LT4+LT3 can restore euthyroidism while maintaining a normal serum TSH. An observational study of 400 patients with a mean follow-up of ∼9 years did not indicate increased mortality or morbidity risk due to cardiovascular disease, atrial fibrillation, or fractures after adjusting for age when compared with patients taking only LT4. Desiccated thyroid extract (DTE) is a form of combination therapy in which the LT4/LT3 ratio is ∼4:1; the mean daily dose of DTE needed to normalize serum TSH contains ∼11 mcg T3, but some patients may require higher doses. The DTE remains outside formal FDA oversight, and consistency of T4 and T3 contents is monitored by the manufacturers only. Conclusions: Newly diagnosed hypothyroid patients should be treated with LT4. A trial of combination therapy with LT4+LT3 can be considered for those patients who have unambiguously not benefited from LT4.
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Affiliation(s)
- Thaer Idrees
- Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, Illinois, USA
| | - Scott Palmer
- Department of Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Rui M.B. Maciel
- Division of Endocrinology, Universidade Federal de Sao Paulo, Sao Paulo, Brazil
| | - Antonio C. Bianco
- Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, Illinois, USA
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Izkhakov E, Vaisman N, Barnes S, Barchana M, Stern N, Keinan-Boker L. Body Composition, Resting Energy Expenditure, and Metabolic Changes in Women Diagnosed with Differentiated Thyroid Carcinoma. Thyroid 2019; 29:1044-1051. [PMID: 31088334 PMCID: PMC6707037 DOI: 10.1089/thy.2018.0483] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background: Thyroid hormones heavily impact energy expenditure, body mass, and body composition. Their role in the state of exogenous subclinical hyperthyroidism in differentiated thyroid carcinoma (DTC) patients, however, is less well defined. The first aim of this study was to assess changes in body weight, body composition, resting energy expenditure (REE), respiratory quotient (RQ), and metabolic parameters in female DTC patients, starting from the phase of a euthyroid state before total thyroidectomy through the subsequent year after thyrotropin (TSH) suppression. The second aim was to assess the relationship between these variables and thyroid function parameters. Methods: This observational case series analyzed changes in body composition, calorimetric, and metabolic parameters of 15 DTC female patients at 5 time points: (1) at initial DTC diagnosis (euthyroid state), (2) at 2-3 weeks after thyroidectomy (hypothyroid state), (3) at 2-3 months of levothyroxine (LT4) treatment (exogenous euthyroid state), (4) after 6-9 months, and (5) after 1 year of TSH suppressive LT4 therapy (exogenous subclinical hyperthyroid state). A generalized estimating equation (GEE) analysis was performed to estimate the longitudinal correlations of the total triiodothyronine (TT3)/free thyroxine (fT4) ratio (as an independent variable) with body composition, metabolic, and calorimetric parameter changes (as dependent variables). Results: REE, REE per kilogram of lean body mass (REE/LBM), pulse, and systolic and diastolic blood pressure were significantly higher after TSH suppressive LT4 therapy. The GEE analysis revealed longitudinal negative correlations between the TT3/fT4 ratio and systolic blood pressure, fasting blood glucose, body mass index, android (abdominal wall and visceral mesentery) fat distribution, trunk, and arm fat distribution, REE, and REE/LBM. There was a positive correlation with RQ. Conclusions: REE, REE/LBM, pulse, and systolic and diastolic blood pressure were significantly higher after thyroidectomy, radioiodine and TSH suppressive therapy in female DTC patients, while no changes were observed in body weight or body composition. A lower TT3/fT4 ratio longitudinally correlated with increases in REE, REE/LBM, abdominal fat distribution, systolic blood pressure, and fasting blood glucose, as well as with decreased RQ. These findings highlight the importance of judicial balancing of the benefits and detriments of TSH suppression with subsequent decreased TT3/fT4 ratios for female DTC patients.
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Affiliation(s)
- Elena Izkhakov
- Institute of Endocrinology, Metabolism and Hypertension; Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- School of Public Health, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel
| | - Nachum Vaisman
- Unit of Clinical Nutrition, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Sophie Barnes
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Ultrasound Division of Imaging, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Micha Barchana
- School of Public Health, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel
| | - Naftali Stern
- Institute of Endocrinology, Metabolism and Hypertension; Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Lital Keinan-Boker
- School of Public Health, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel
- National Cancer Registry, Israel Center for Disease Control, Ministry of Health, Ramat Gan, Israel
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4
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Rosenbaum M, Goldsmith RL, Haddad F, Baldwin KM, Smiley R, Gallagher D, Leibel RL. Triiodothyronine and leptin repletion in humans similarly reverse weight-loss-induced changes in skeletal muscle. Am J Physiol Endocrinol Metab 2018; 315:E771-E779. [PMID: 29920214 PMCID: PMC6293163 DOI: 10.1152/ajpendo.00116.2018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Subjects maintaining a ≥10% dietary weight loss exhibit decreased circulating concentrations of bioactive thyroid hormones and increased skeletal muscle work efficiency largely due to increased expression of more-efficient myosin heavy chain (MHC) isoforms (MHC I) and significantly mediated by the adipocyte-derived hormone leptin. The primary purpose of this study was to examine the effects of triiodothyronine (T3) repletion on energy homeostasis and skeletal muscle physiology in weight-reduced subjects and to compare these results with the effects of leptin repletion. Nine healthy in-patients with obesity were studied at usual weight (Wtinitial) and following a 10% dietary weight loss while receiving 5 wk of a placebo (Wt-10%placebo) or T3 (Wt-10%T3) in a single-blind crossover design. Primary outcome variables were skeletal muscle work efficiency and vastus lateralis muscle mRNA expression. These results were compared with the effects of leptin repletion in a population of 22 subjects, some of whom participated in a previous study. At Wt-10%placebo, skeletal muscle work efficiency and relative expression of the more-efficient/less-efficient MHC I/MHC II isoforms were significantly increased and the ratio of the less-efficient to the more-efficient sarco(endo)plasmic reticulum Ca2+-ATPase isoforms (SERCA1/SERCA2) was significantly decreased. These changes were largely reversed by T3 repletion to a degree similar to the changes that occurred with leptin repletion. These data support the hypothesis that the effects of leptin on energy expenditure in weight-reduced individuals are largely mediated by T3 and suggest that further study of the possible role of thyroid hormone repletion as adjunctive therapy to help sustain weight loss is needed.
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Affiliation(s)
- Michael Rosenbaum
- Departments of Pediatrics and Medicine, Columbia University College of Physicians and Surgeons, New York, New York
| | - Rochelle L Goldsmith
- Division of Cardiology, Department of Medicine, Columbia University College of Physicians and Surgeons , New York, New York
| | - Fadia Haddad
- Department of Physiology and Biophysics, University of California at Irvine , Irvine, California
| | - Kenneth M Baldwin
- Department of Physiology and Biophysics, University of California at Irvine , Irvine, California
| | - Richard Smiley
- Departments of Pediatrics and Medicine, Columbia University College of Physicians and Surgeons, New York, New York
- Department of Anesthesia, Columbia University College of Physicians and Surgeons , New York, New York
| | - Dympna Gallagher
- Obesity Research Center, Columbia University, St. Luke's-Roosevelt Hospital , New York, New York
| | - Rudolph L Leibel
- Departments of Pediatrics and Medicine, Columbia University College of Physicians and Surgeons, New York, New York
- Division of Molecular Genetics, Columbia University College of Physicians and Surgeons , New York, New York
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Polidori D, Sanghvi A, Seeley RJ, Hall KD. How Strongly Does Appetite Counter Weight Loss? Quantification of the Feedback Control of Human Energy Intake. Obesity (Silver Spring) 2016; 24:2289-2295. [PMID: 27804272 PMCID: PMC5108589 DOI: 10.1002/oby.21653] [Citation(s) in RCA: 141] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/27/2016] [Accepted: 07/26/2016] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To quantify the feedback control of energy intake in response to long-term covert manipulation of energy balance in free-living humans. METHODS A validated mathematical method was used to calculate energy intake changes during a 52-week placebo-controlled trial in 153 patients treated with canagliflozin, a sodium glucose co-transporter inhibitor that increases urinary glucose excretion, thereby resulting in weight loss without patients being directly aware of the energy deficit. The relationship between the body weight time course and the calculated energy intake changes was analyzed using principles from engineering control theory. RESULTS It was discovered that weight loss leads to a proportional increase in appetite resulting in eating above baseline by ∼100 kcal/day per kilogram of lost weight-an amount more than threefold larger than the corresponding energy expenditure adaptations. CONCLUSIONS While energy expenditure adaptations have often been considered the main reason for slowing of weight loss and subsequent regain, feedback control of energy intake plays an even larger role and helps explain why long-term maintenance of a reduced body weight is so difficult.
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Affiliation(s)
- David Polidori
- Janssen Research & Development, LLC, San Diego, California, USA
| | - Arjun Sanghvi
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Randy J Seeley
- Department of Surgery, University of Michigan, Ann Arbor, Michigan, USA
| | - Kevin D Hall
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA.
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Samuels MH, Kolobova I, Smeraglio A, Peters D, Purnell JQ, Schuff KG. Effects of Levothyroxine Replacement or Suppressive Therapy on Energy Expenditure and Body Composition. Thyroid 2016; 26:347-55. [PMID: 26700485 PMCID: PMC4790206 DOI: 10.1089/thy.2015.0345] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Thyrotropin (TSH)-suppressive doses of levothyroxine (LT4) have adverse effects on bone and cardiac function, but it is unclear whether metabolic function is also affected. The objective of this study was to determine whether women receiving TSH-suppressive LT4 doses have alterations in energy expenditure or body composition. METHODS This study was a cross-sectional comparison between three groups of women: 26 women receiving chronic TSH-suppressive LT4 doses, 80 women receiving chronic replacement LT4 doses, and 16 untreated euthyroid control women. Subjects underwent measurements of resting energy expenditure (REE), substrate oxidation, and thermic effect of food by indirect calorimetry; physical activity energy expenditure by accelerometer; caloric intake by 24-hour diet recall; and body composition by dual X-ray absorptiometry. RESULTS REE per kilogram lean body mass in the LT4 euthyroid women was 6% lower than that of the LT4-suppressed group, and 4% lower than that of the healthy control group (p = 0.04). Free triiodothyronine (fT3) levels were directly correlated with REE, and were 10% lower in the LT4 euthyroid women compared with the other two groups (p = 0.007). The groups of subjects did not differ in other measures of energy expenditure, caloric intake, or body composition. CONCLUSIONS LT4 suppression therapy does not adversely affect energy expenditure or body composition in women. However, LT4 replacement therapy is associated with a lower REE, despite TSH levels within the reference range. This may be due to lower fT3 levels, suggesting relative tissue hypothyroidism may contribute to impaired energy expenditure in LT4 therapy.
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Affiliation(s)
- Mary H. Samuels
- Division of Endocrinology, Diabetes, and Clinical Nutrition, Oregon Health and Science University, Portland, Oregon
| | - Irina Kolobova
- Division of Endocrinology, Diabetes, and Clinical Nutrition, Oregon Health and Science University, Portland, Oregon
| | - Anne Smeraglio
- Department of Internal Medicine, Stanford University School of Medicine, Stanford, California
| | - Dawn Peters
- Division of Biostatistics, Oregon Health and Science University, Portland, Oregon
| | - Jonathan Q. Purnell
- Division of Endocrinology, Diabetes, and Clinical Nutrition, Oregon Health and Science University, Portland, Oregon
| | - Kathryn G. Schuff
- Division of Endocrinology, Diabetes, and Clinical Nutrition, Oregon Health and Science University, Portland, Oregon
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Kim DH, Choi DH, Kim HW, Choi SW, Kim BB, Chung JW, Koh YY, Chang KS, Hong SP. Prediction of infarct severity from triiodothyronine levels in patients with ST-elevation myocardial infarction. Korean J Intern Med 2014; 29:454-65. [PMID: 25045293 PMCID: PMC4101592 DOI: 10.3904/kjim.2014.29.4.454] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 09/04/2013] [Accepted: 10/28/2013] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND/AIMS The aim of the present study was to evaluate the relationship between thyroid hormone levels and infarct severity in patients with ST-elevation myocardial infarction (STEMI). METHODS We retrospectively reviewed thyroid hormone levels, infarct severity, and the extent of transmurality in 40 STEMI patients evaluated via contrast-enhanced cardiac magnetic resonance imaging. RESULTS The high triiodothyronine (T3) group (≥ 68.3 ng/dL) exhibited a significantly higher extent of transmural involvement (late transmural enhancement > 75% after administration of gadolinium contrast agent) than did the low T3 group (60% vs. 15%; p = 0.003). However, no significant difference was evident between the high- and low-thyroid-stimulating hormone/free thyroxine (FT4) groups. When the T3 cutoff level was set to 68.3 ng/dL using a receiver operating characteristic curve, the sensitivity was 80% and the specificity 68% in terms of differentiating between those with and without transmural involvement. Upon logistic regression analysis, high T3 level was an independent predictor of transmural involvement after adjustment for the presence of diabetes mellitus (DM) and the use of glycoprotein IIb/IIIa inhibitors (odds ratio, 40.62; 95% confidence interval, 3.29 to 502; p = 0.004). CONCLUSIONS The T3 level predicted transmural involvement that was independent of glycoprotein IIb/IIIa inhibitor use and DM positivity.
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Affiliation(s)
- Dong Hun Kim
- Department of Radiology, Chosun University School of Medicine, Gwangju, Korea
| | - Dong-Hyun Choi
- Department of Internal Medicine, Chosun University School of Medicine, Gwangju, Korea
| | - Hyun-Wook Kim
- Department of Internal Medicine, Chosun University School of Medicine, Gwangju, Korea
| | - Seo-Won Choi
- Department of Internal Medicine, Chosun University School of Medicine, Gwangju, Korea
| | - Bo-Bae Kim
- Department of Internal Medicine, Chosun University School of Medicine, Gwangju, Korea
| | - Joong-Wha Chung
- Department of Internal Medicine, Chosun University School of Medicine, Gwangju, Korea
| | - Young-Youp Koh
- Department of Internal Medicine, Chosun University School of Medicine, Gwangju, Korea
| | - Kyong-Sig Chang
- Department of Internal Medicine, Chosun University School of Medicine, Gwangju, Korea
| | - Soon-Pyo Hong
- Department of Internal Medicine, Chosun University School of Medicine, Gwangju, Korea
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Johannsen DL, Galgani JE, Johannsen NM, Zhang Z, Covington JD, Ravussin E. Effect of short-term thyroxine administration on energy metabolism and mitochondrial efficiency in humans. PLoS One 2012; 7:e40837. [PMID: 22844412 PMCID: PMC3406028 DOI: 10.1371/journal.pone.0040837] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 06/16/2012] [Indexed: 11/28/2022] Open
Abstract
The physiologic effects of triiodothyronine (T3) on metabolic rate are well-documented; however, the effects of thyroxine (T4) are less clear despite its wide-spread use to treat thyroid-related disorders and other non-thyroidal conditions. Here, we investigated the effects of acute (3-day) T4 supplementation on energy expenditure at rest and during incremental exercise. Furthermore, we used a combination of in situ and in vitro approaches to measure skeletal muscle metabolism before and after T4 treatment. Ten healthy, euthyroid males were given 200 µg T4 (levothyroxine) per day for 3 days. Energy expenditure was measured at rest and during exercise by indirect calorimetry, and skeletal muscle mitochondrial function was assessed by in situ ATP flux (31P MRS) and in vitro respiratory control ratio (RCR, state 3/state 4 rate of oxygen uptake using a Clark-type electrode) before and after acute T4 treatment. Thyroxine had a subtle effect on resting metabolic rate, increasing it by 4% (p = 0.059) without a change in resting ATP demand (i.e., ATP flux) of the vastus lateralis. Exercise efficiency did not change with T4 treatment. The maximal capacity to produce ATP (state 3 respiration) and the coupled state of the mitochondria (RCR) were reduced by approximately 30% with T4 (p = 0.057 and p = 0.04, respectively). Together, the results suggest that T4, although less metabolically active than T3, reduces skeletal muscle efficiency and modestly increases resting metabolism even after short-term supplementation. Our findings may be clinically relevant given the expanding application of T4 to treat non-thyroidal conditions such as obesity and weight loss.
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Affiliation(s)
- Darcy L. Johannsen
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
| | - Jose E. Galgani
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Neil M. Johannsen
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
| | - Zhengyu Zhang
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
| | - Jeffrey D. Covington
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
| | - Eric Ravussin
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
- * E-mail:
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Abstract
We here discuss the role of brown adipose tissue on energy homeostasis and assess its potential as a target for body weight management. Because of their high number of mitochondria and the presence of uncoupling protein 1, brown fat adipocytes can be termed as energy inefficient for adenosine-5'-triphosphate (ATP) production but energy efficient for heat production. Thus, the energy inefficiency of ATP production, despite high energy substrate oxidation, allows brown adipose tissue to generate heat for body temperature regulation. Whether such thermogenic property also plays a role in body weight regulation is still debated. The recent (re)discovery of brown adipose tissue in human adults and a better understanding of brown adipose tissue development have encouraged the quest for new alternatives to treat obesity since obese individuals seem to have less brown adipose tissue mass/activity than do their lean counterparts. In this review, we discuss the physiological relevance of brown adipose tissue on thermogenesis and its potential usefulness on body weight control in humans.
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Affiliation(s)
- Eric Ravussin
- Human Physiology, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
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Sartorio A, Ferrero S, Trecate L, Bedogni G. Thyroid function is more strongly associated with body impedance than anthropometry in healthy subjects. J Endocrinol Invest 2002; 25:620-3. [PMID: 12150337 DOI: 10.1007/bf03345086] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Since fat-free tissues are responsible for 95% of basal energy expenditure, fat-free mass is expected to be a better determinant of thyroid size and function than anthropometry. We tested the hypothesis that fat-free tissues as qualitatively determined by body resistance (R) at 50 kHz are more strongly associated with TSH than anthropometric indicators in healthy subjects. A number of 78 euthyroid adults of both sexes were consecutively studied. R was the best single predictor of TSH (R2(adj)=0.65, p<0.0001). It explained 36% more variance than bw (R2(adj)=0.29, p<0.0001), the most accurate anthropometric predictor. Sex had no effect on the relationship between TSH, bioelectrical impedance analysis and anthropometry. After the contribution of R to TSH was taken into account, anthropometric indicators were not able to explain any additional part of TSH variance. We conclude that in healthy subjects, bioelectrical resistance is a better indicator of thyroid function than anthropometry, probably because of its more direct relationship with fat-free tissues. Further studies are needed to test whether this relationship holds in under- and over-weight subjects.
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Affiliation(s)
- A Sartorio
- Division of Metabolic Diseases III, Istituto Auxologico Italiano, IRCCS, Piancavallo, Verbania, Italy
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