- Email: [email protected]
Eating behavior and thyroid disease in female obese patients
Eating Behaviors 4 (2003) 173 – 179
Eating behavior and thyroid disease in female obese patients Edoardo Mannuccia, Valdo Riccab, Simona Filettia, Maura Boldrinib, C.M. Rotellaa,* a
b
Endocrine Unit, Department of Clinical Pathophysioloy, University of Florence, Italy Psychiatry Unit, Department of Neurological Psychiatric Sciences, University of Florence, Italy
Abstract It has been suggested that preexisting thyroid disease (TD) could be a risk factor for the development of eating disorders. The aim of this study was to compare eating attitudes and behavior in female obese patients with and without TD. Thyrotropin (TSH) was determined in 256 patients aged 44.9 ± 14.7 years with body mass index (BMI) >30 kg/m2; eating attitudes and behavior were assessed with the Eating Disorder Examination (EDE). EDE Shape Concern score was significantly higher in patients with previous or current hypothyroidism (N = 30) than in the rest of the sample. Among patients without known TD, no difference in eating attitudes was observed between patients with elevated TSH (N = 24; 11%) and those with normal thyroid function. The prevalence of binge eating disorder (BED) in the total sample was 9.7%; no difference in prevalence was observed between patients with and without a history of hypothyroidism, and between those with and without previously unknown hypothyroidism. In conclusion, known hypothyroidism is associated with increased shape concern; this does not appear to be related to differences in current levels of thyroid hormones or related hormones. D 2003 Published by Elsevier Science Ltd. Keywords: Hypothyroidism; Hyperthyroidism; Obesity; Eating disorders
* Corresponding author. Malattie del Metabolismo e Diabetologia, Dipartimento di Fisiopatologia Clinica, Viale Pieraccini, 6, 50134 Florence, Italy. Tel.: +39-55-4279960; fax: +39-55-4271413. E-mail address: [email protected] (C.M. Rotella). 1471-0153/03/$ – see front matter D 2003 Published by Elsevier Science Ltd. doi:10.1016/S1471-0153(03)00012-6
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1. Introduction Following some case reports of eating disorders associated with thyroid disease (TD) (Byerley & Heber, 1996; Kuboki, Suematsu, Ogata, Yamamoto, & Shizume, 1987), it has been suggested that abnormalities of thyroid function could facilitate the onset of eating disturbances (Tiller, Macrae, Schmidt, Bloom, & Treasure, 1994). In particular, it has been hypothesized that weight fluctuations occurring after the onset of hypo- and hyperthyroidism and the initiation of treatment could focus the of patients’ attention on body weight and shape, precipitating eating disorder symptoms in susceptible individuals. On the other hand, mood fluctuations induced by thyroid dysfunction could contribute to the pathogenesis of eating behavior disturbances. Few systematic studies have been performed in order to assess the association of eating disorders and TD. A high prevalence of eating disturbances has been reported in a small, noncontrolled sample of women with TD (Tiller et al., 1994). However, subjects with TD have been shown to have a higher prevalence of any mental disorder when compared with the general population (Placidi et al., 1998), suggesting that the association could be nonspecific. On the other hand, another small study showed a higher prevalence of thyroid dysfunction in patients with eating disorders when compared to subjects with major depression or healthy controls (Hall et al., 1995). The aim of this study was to compare eating attitudes and behavior in subjects with and without TD, within a cohort of obese female patients seeking treatment for weight loss.
2. Patients and methods A consecutive series of female obese (body mass index, or BMI>30 kg/m2) outpatients aged 18–70 years referring for the first time for weight management to the Outpatient Clinic of the Section of Metabolic Diseases of the Endocrinology Unit of the University of Florence were included. Subjects with known diabetes mellitus were not enrolled in the study, as well as those who did not provide their informed consent. A total of 256 patients were enrolled. Participants had an age (mean ± S.D.) of 44.9 ± 14.7 years, and a BMI (median [quartiles]) of 36.1 [32.5–40.4] kg/m2. The study did not involve therapeutic or diagnostic procedures different from the standard clinical care applied in the Outpatient Clinic mentioned above. For this reason, submission to the Ethical Committee of the University of Florence was not needed. Each patient was interviewed at the first visit, in order to assess known current or previous TD (hypo- or hyperthyroidism). Thyrotropin (TSH) blood levels were determined through a chemoluminescent immunoassay (Chiron Diagnostic, East Walpole, MA, USA) on a sample of venous blood drawn in the morning after overnight fast within 10 days from the first visit. The upper limit of the normal range for this assay is 4 mU/l. In patients with elevated TSH, the determination was repeated, and free thyroxine and triiodothyronine were also determined, together with anti-thyroperoxydase and anti-thyroglobulin autoantibodies; thyroxine treatment was initiated when TSH was >5 mU/l and symptoms of hypothyroid-
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ism and/or elevated antithyroid autoantibodies were present, and in any case when TSH was >10 mU/l. Eating attitude and behaviors were assessed by the Eating Disorder Examination (EDE 12.0D), a semistructured interview consisting of four subscales (Restraint, Eating Concern, Weight Concern and Shape Concern) plus several items that investigate the frequency of binge eating and compensatory behaviors. The global score provides a measure of the eating disorder severity, while the subscale scores define the psychopathological profile of individual patients (Fairburn & Cooper, 1993). The interview was used in its validated Italian version (Mannucci et al., 1997). The diagnosis of binge eating disorder (BED), according to DSM-IV criteria (American Psychiatric Association, 1994), was formulated through a face-to-face interview. Normally distributed data were expressed as mean ± S.D., while non-normally distributed parameters, or parameters of unknown distribution, were expressed as median [quartiles]. Unpaired Student’s t test and Mann–Whitney U tests were used for comparison of normally and non-normally distributed parameters, respectively, while chi square test was used for comparisons of categorial variables.
3. Results Out of the 256 patients enrolled, 33 (13%) reported known of lifetime hypo- or hyperthyroidism at the first visit. Among those, none of the patients were affected by current hyperthyroidism, while 3 reported a previous hyperthyroidism, but were not presently receiving any treatment. Sixteen patients were currently affected by clinical or subclinical hypothyroidism; of those, 14 were treated with L-thyroxine. Fourteen patients reported a previous hypothyroidism, without any present thyroid dysfunction. The patients affected by known current or previous hypothyroidism did not differ significantly from the rest of the sample for age (45.9 ± 10.3 versus 44.8 ± 15.2 years) and BMI (36.0 [34.1–39.0] versus 36.1 [32.3–41.0] kg/m2). Median TSH levels were not significantly different in patients with current or previous hypothyroidism when compared to those without known thyroid dysfunction (2.3 [1.5–3.7] versus 2.1 [1.4–3.5] mU/l). Only 2 of the patients with known previous or current hypothyroidism had TSH>4 mU/l. Among the 223 patients who did not report a previous or current thyroid dysfunction, 24 (11.0%) showed a TSH>4 mU/l (median: 5.3 [4.3–7.9]), suggestive of current, previously unknown, hypothyroidism. None of the patients showed a TSH below the normal range. Patients with previously unknown hypothyroidism did not differ significantly from the patients who did not report a previous or current TD for age (40.59 ± 15.51 versus 45.25 ± 15.43 years) and BMI (36.1[33.25–41.4] versus 36.1 [32.8–40.4] kg/m2). In the total sample, EDE median total score was 2.1 [1.6–2.7]. Scores of EDE subscales were 1.2 [0.4–1.8] for Restriction, 0.8 [0.0–1.8] for Eating Concern, 2.4 [2.0–3.2] for Weight Concern, 3.7 [2.8–4.3] for Shape Concern. Forty-eight patients (18.7%) reported binge eating episodes during the last 3 months; 25 (9.7%) of those fulfilled DSM-IV criteria for the diagnosis of BED. Of the 25 patients with BED, 2 (8%) were affected by current
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Fig. 1. EDE total and subscale scores (median [quartiles]) in patients with known previous or current hypothyroidism (empty bars) and without reported history of thyroid disease (grey bars). R = restriction, EC = eating concern, WC = weight concern, SC = shape concern. * P < .05.
known hypothyroidism, while 3 (12%) had no known thyroid dysfunction but showed a TSH>4 mU/l. The prevalence of known or previously unknown hypothyroidism in patients with BED was not significantly different from the rest of the sample; similarly, no significant difference in the prevalence of BED was observed between patients with or without previously known or unknown thyroid dysfunction. EDE total and subscale scores in patients with known previous or current hypothyroidism and without TD are reported in Fig. 1. Patients who reported hypothyroidism showed significantly higher total and Shape Concern scores; no other significant difference was observed. EDE scores of patients without known previous or current TD, with TSH>4 mU/l, were not significantly different from those of subjects with normal thyroid function (Fig. 2).
Fig. 2. EDE total and subscale scores (median [quartiles]) in patients with TSH>4 mU/l (empty bars) and with TSH 4 mU/l (grey bars) among those without known previous or current thyroid disease. R = restriction, EC = eating concern, WC = weight concern, SC = shape concern.
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In the total sample, 14.4% of patients reported at least one episode of binge eating in the last month. The proportion of patients reporting binge eating was 15% (5/30) in those with previously known hypothyroidism, and 14% (32/223) in those without known TD ( p = ns). No significant difference in the number of eating binges in the last month was observed between the two groups.
4. Discussion A relatively high prevalence of known previous or current TD was found in the present sample. One possibility is that the previous hypothyroidism could have contributed to weight gain in some of the patients. It should also be considered that the Outpatient Clinic in which the patients were enrolled is part of the Unit of Endocrinology of the University Hospital, and obese patients with known thyroid disorders could be overrepresented in the sample. Among those who did not report previously known TD, a relevant proportion showed a TSH over the upper limit of the normal range, suggesting an existing hypothyroidism. The prevalence of previously unknown hypothyroidism was higher than that recently reported in a general population sample in Northern Italy (Rivolta et al., 1999). This difference could be due to the fact that the present sample is composed of obese individuals, in whom altered thyroid function could have contributed to weight gain. Furthermore, patients with unknown hypothyroidism could be more resistant to standard weight loss programs, and could therefore be more likely to refer to a specialized University Clinic. The prevalence of previously known or unknown hypothyroidism observed in the present study should not be considered representative of the total population of obese subjects, being probably in part the result of self-selection of patients at referral. However, the relevant proportion of subjects without a diagnosis of TD but with abnormal thyroid function suggests the usefulness of the determination of TSH for the routine screening of subclinical hypothyroidism in all obese patients seeking weight loss in specialized Outpatient Clinics. The prevalence of BED in the present sample was similar to that previously reported by our group in a similar setting (Ricca et al., 2000). Although previous studies have reported a much higher prevalence of BED in obese patients (Stunkard et al., 1996), differences in assessment methods and recruitment procedures could account for discrepancies in results (Varnado et al., 1997). Patients with known previous or current hypothyroidism showed a higher concern about body shape than the rest of the sample. This finding, consistent with previous reports (Hall et al., 1995; Tiller et al., 1994), suggests that TD could really affect attitudes toward shape, weight, or eating. It could be speculated that weight fluctuations at the onset of TD and at the initiation of treatment could focus the attention of patients’ attention of on body shape, determining the observed increase in EDE Shape Concern scores. An increased shape concern could, in turn, induce a greater restraint and eventually loss of control over eating, in susceptible individuals. This hypothesis deserves to be investigated through specifically
178
E. Mannucci et al. / Eating Behaviors 4 (2003) 173–179
designed studies assessing the weight history of obese patients with or without previous or current hypothyroidism. Thyroid disease is also associated with mood fluctuations, which could determine abnormalities in eating attitudes in some subjects; on the other hand, the occurrence of depressive symptoms could lead to a screening for thyroid dysfunction, and patients with affective disorders could therefore be more likely to receive a diagnosis of hypothyroidism. Furthermore, thyroid dysfunction has been reported to be associated with increased prevalence of general psychopathology, (Placidi et al., 1998), which could explain the observed differences in eating attitudes between subjects with and without hypothyroidism. The relatively small size of the present sample does not allow any multivariate analysis, adjusting differences in eating attitudes and behavior for mood depression and associated psychopathology. Studies on larger samples of obese patients, with an accurate assessment of other psychopathological domains as well as eating attitudes and behavior, are needed to clarify this point. Differences in eating attitudes could also theoretically be the consequence of altered levels of thyroid hormones. In fact, it is known that thyrotropin-releasing hormone (TRH), TSH, and thyroid hormones are involved in the regulation of eating behavior (Krotkiewski, 2000). However, in the present study, no difference in eating attitudes and behavior was observed between patients with or without previously unknown hypothyroidism. This suggests that the increased shape concern observed in subjects with known previous or current TD was not related to thyroid hormones blood levels. No difference in the prevalence of BED was observed between patients with or without a diagnosis of hypothyroidism. It is noteworthy that the small sample size could have prevented the detection of minor differences in prevalence. The only previous study of similar design, in which a difference in the prevalence of BED was observed, assessed ‘‘subclinical’’ or ‘‘subthreshold’’ eating disorders together with formal eating disorders defined by DSM-IV criteria (Tiller et al., 1994); this could explain the discrepancy in results. Furthermore, the present study, unlike previous investigations (Hall et al., 1995; Tiller et al., 1994), was performed in obese subjects, that could have shown a greater level of eating disturbances than the general population, irrespective of their thyroid status. Further studies on larger samples of lean and obese subjects are needed in order to verify eventual, small differences in the prevalence of eating disorders, and of BED in particular, among patients with or without TD. In conclusion, known previous or current hypothyroidism appears to be associated to higher body shape concern in obese individuals while previously unknown hypothyroidism, which was frequent in the sample studied, was not associated with any significant modification of eating attitudes and behavior. Thyroid disease could modify eating attitudes, although its effects on eating behavior need to be further investigated.
References American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders. 4th ed. (DSM-IV). Washington, DC: APA Press.
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Byerley, L. O., & Heber, D. (1996). Metabolic effects of triiodothyronine replacement during fasting in obese subjects. Journal of Clinical Endocrinology and Metabolism, 81, 968 – 976. Fairburn, C. G., & Cooper, Z. (1993). The Eating Disorder Examination. In C. G. Fairburn, & G. T. Wilson (Eds.), Binge eating: Nature, assessment and treatment ( pp. 317 – 360). New York: Guildford Press. Hall, R. C., Dunlap, P. K., Hall, R. C., Pacheco, C. A., Blakey, R. K., & Abraham, J. (1995). Thyroid disease and abnormal thyroid function tests in women with eating disorders and depression. Journal of Florida Medical Association, 82, 187 – 192. Krotkiewski, M. (2000). Thyroid hormones and treatment of obesity. International Journal of Obesity and Related Metabolic Disorders, 24, S116 – S119. Kuboki, T., Suematsu, H., Ogata, E., Yamamoto, M., & Shizuma, K. (1987). Two cases of anorexia nervosa associated with Graves’ disease. Endocrinology Japan, 34, 9 – 12. Placidi, G. P., Boldrini, M., Patronelli, A., Fiore, E., Chiovato, L., Perugi, G., & Marazziti, D. (1998). Prevalence of psychiatric disorders in thyroid diseased patients. Neuropsychobiology, 38, 222 – 225. Ricca, V., Mannucci, E., Moretti, S., Di Bernardo, M., Zucchi, T., Cabras, P. L., & Rotella, C. M. (2000). Screening for binge eating disorder in obese outpatients. Comprehensive Psychiatry, 41, 111 – 115. Rivolta, G., Cerutti, R., Colombo, R., Miano, G., Dionisio, P., & Grossi, E. (1999). Prevalence of subclinical hypothyroidism in a population living in the Milan metropolitan area. Journal of Endocrinological Investigation, 22, 693 – 697. Stunkard, A., Berkowitz, R., Wadden, T., Tanrikut, C., Reiss, E., & Young, L. (1996). Binge eating disorder and the night-eating syndrome. International Journal of Obesity and Related Metabolic Disorders, 20, 1 – 6. Tiller, J., Macrae, A., Schmidt, U., Bloom, S., & Treasure, J. (1994). The prevalence of eating disorders in thyroid disease: A pilot study. Journal of Psychosomatic Research, 38, 609 – 616. Varnado, P. J., Williamson, D. A., Bentz, B. G., Ryan, D. H., Rhodes, S. K., & O’Neil, P. M. (1997). Prevalence of binge eating disorder in obese persons seeking weight loss treatment. Eating and Weight Disorders, 2, 117 – 124.
Eating behavior and thyroid disease in female obese patients Edoardo Mannuccia, Valdo Riccab, Simona Filettia, Maura Boldrinib, C.M. Rotellaa,* a
b
Endocrine Unit, Department of Clinical Pathophysioloy, University of Florence, Italy Psychiatry Unit, Department of Neurological Psychiatric Sciences, University of Florence, Italy
Abstract It has been suggested that preexisting thyroid disease (TD) could be a risk factor for the development of eating disorders. The aim of this study was to compare eating attitudes and behavior in female obese patients with and without TD. Thyrotropin (TSH) was determined in 256 patients aged 44.9 ± 14.7 years with body mass index (BMI) >30 kg/m2; eating attitudes and behavior were assessed with the Eating Disorder Examination (EDE). EDE Shape Concern score was significantly higher in patients with previous or current hypothyroidism (N = 30) than in the rest of the sample. Among patients without known TD, no difference in eating attitudes was observed between patients with elevated TSH (N = 24; 11%) and those with normal thyroid function. The prevalence of binge eating disorder (BED) in the total sample was 9.7%; no difference in prevalence was observed between patients with and without a history of hypothyroidism, and between those with and without previously unknown hypothyroidism. In conclusion, known hypothyroidism is associated with increased shape concern; this does not appear to be related to differences in current levels of thyroid hormones or related hormones. D 2003 Published by Elsevier Science Ltd. Keywords: Hypothyroidism; Hyperthyroidism; Obesity; Eating disorders
* Corresponding author. Malattie del Metabolismo e Diabetologia, Dipartimento di Fisiopatologia Clinica, Viale Pieraccini, 6, 50134 Florence, Italy. Tel.: +39-55-4279960; fax: +39-55-4271413. E-mail address: [email protected] (C.M. Rotella). 1471-0153/03/$ – see front matter D 2003 Published by Elsevier Science Ltd. doi:10.1016/S1471-0153(03)00012-6
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E. Mannucci et al. / Eating Behaviors 4 (2003) 173–179
1. Introduction Following some case reports of eating disorders associated with thyroid disease (TD) (Byerley & Heber, 1996; Kuboki, Suematsu, Ogata, Yamamoto, & Shizume, 1987), it has been suggested that abnormalities of thyroid function could facilitate the onset of eating disturbances (Tiller, Macrae, Schmidt, Bloom, & Treasure, 1994). In particular, it has been hypothesized that weight fluctuations occurring after the onset of hypo- and hyperthyroidism and the initiation of treatment could focus the of patients’ attention on body weight and shape, precipitating eating disorder symptoms in susceptible individuals. On the other hand, mood fluctuations induced by thyroid dysfunction could contribute to the pathogenesis of eating behavior disturbances. Few systematic studies have been performed in order to assess the association of eating disorders and TD. A high prevalence of eating disturbances has been reported in a small, noncontrolled sample of women with TD (Tiller et al., 1994). However, subjects with TD have been shown to have a higher prevalence of any mental disorder when compared with the general population (Placidi et al., 1998), suggesting that the association could be nonspecific. On the other hand, another small study showed a higher prevalence of thyroid dysfunction in patients with eating disorders when compared to subjects with major depression or healthy controls (Hall et al., 1995). The aim of this study was to compare eating attitudes and behavior in subjects with and without TD, within a cohort of obese female patients seeking treatment for weight loss.
2. Patients and methods A consecutive series of female obese (body mass index, or BMI>30 kg/m2) outpatients aged 18–70 years referring for the first time for weight management to the Outpatient Clinic of the Section of Metabolic Diseases of the Endocrinology Unit of the University of Florence were included. Subjects with known diabetes mellitus were not enrolled in the study, as well as those who did not provide their informed consent. A total of 256 patients were enrolled. Participants had an age (mean ± S.D.) of 44.9 ± 14.7 years, and a BMI (median [quartiles]) of 36.1 [32.5–40.4] kg/m2. The study did not involve therapeutic or diagnostic procedures different from the standard clinical care applied in the Outpatient Clinic mentioned above. For this reason, submission to the Ethical Committee of the University of Florence was not needed. Each patient was interviewed at the first visit, in order to assess known current or previous TD (hypo- or hyperthyroidism). Thyrotropin (TSH) blood levels were determined through a chemoluminescent immunoassay (Chiron Diagnostic, East Walpole, MA, USA) on a sample of venous blood drawn in the morning after overnight fast within 10 days from the first visit. The upper limit of the normal range for this assay is 4 mU/l. In patients with elevated TSH, the determination was repeated, and free thyroxine and triiodothyronine were also determined, together with anti-thyroperoxydase and anti-thyroglobulin autoantibodies; thyroxine treatment was initiated when TSH was >5 mU/l and symptoms of hypothyroid-
E. Mannucci et al. / Eating Behaviors 4 (2003) 173–179
175
ism and/or elevated antithyroid autoantibodies were present, and in any case when TSH was >10 mU/l. Eating attitude and behaviors were assessed by the Eating Disorder Examination (EDE 12.0D), a semistructured interview consisting of four subscales (Restraint, Eating Concern, Weight Concern and Shape Concern) plus several items that investigate the frequency of binge eating and compensatory behaviors. The global score provides a measure of the eating disorder severity, while the subscale scores define the psychopathological profile of individual patients (Fairburn & Cooper, 1993). The interview was used in its validated Italian version (Mannucci et al., 1997). The diagnosis of binge eating disorder (BED), according to DSM-IV criteria (American Psychiatric Association, 1994), was formulated through a face-to-face interview. Normally distributed data were expressed as mean ± S.D., while non-normally distributed parameters, or parameters of unknown distribution, were expressed as median [quartiles]. Unpaired Student’s t test and Mann–Whitney U tests were used for comparison of normally and non-normally distributed parameters, respectively, while chi square test was used for comparisons of categorial variables.
3. Results Out of the 256 patients enrolled, 33 (13%) reported known of lifetime hypo- or hyperthyroidism at the first visit. Among those, none of the patients were affected by current hyperthyroidism, while 3 reported a previous hyperthyroidism, but were not presently receiving any treatment. Sixteen patients were currently affected by clinical or subclinical hypothyroidism; of those, 14 were treated with L-thyroxine. Fourteen patients reported a previous hypothyroidism, without any present thyroid dysfunction. The patients affected by known current or previous hypothyroidism did not differ significantly from the rest of the sample for age (45.9 ± 10.3 versus 44.8 ± 15.2 years) and BMI (36.0 [34.1–39.0] versus 36.1 [32.3–41.0] kg/m2). Median TSH levels were not significantly different in patients with current or previous hypothyroidism when compared to those without known thyroid dysfunction (2.3 [1.5–3.7] versus 2.1 [1.4–3.5] mU/l). Only 2 of the patients with known previous or current hypothyroidism had TSH>4 mU/l. Among the 223 patients who did not report a previous or current thyroid dysfunction, 24 (11.0%) showed a TSH>4 mU/l (median: 5.3 [4.3–7.9]), suggestive of current, previously unknown, hypothyroidism. None of the patients showed a TSH below the normal range. Patients with previously unknown hypothyroidism did not differ significantly from the patients who did not report a previous or current TD for age (40.59 ± 15.51 versus 45.25 ± 15.43 years) and BMI (36.1[33.25–41.4] versus 36.1 [32.8–40.4] kg/m2). In the total sample, EDE median total score was 2.1 [1.6–2.7]. Scores of EDE subscales were 1.2 [0.4–1.8] for Restriction, 0.8 [0.0–1.8] for Eating Concern, 2.4 [2.0–3.2] for Weight Concern, 3.7 [2.8–4.3] for Shape Concern. Forty-eight patients (18.7%) reported binge eating episodes during the last 3 months; 25 (9.7%) of those fulfilled DSM-IV criteria for the diagnosis of BED. Of the 25 patients with BED, 2 (8%) were affected by current
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Fig. 1. EDE total and subscale scores (median [quartiles]) in patients with known previous or current hypothyroidism (empty bars) and without reported history of thyroid disease (grey bars). R = restriction, EC = eating concern, WC = weight concern, SC = shape concern. * P < .05.
known hypothyroidism, while 3 (12%) had no known thyroid dysfunction but showed a TSH>4 mU/l. The prevalence of known or previously unknown hypothyroidism in patients with BED was not significantly different from the rest of the sample; similarly, no significant difference in the prevalence of BED was observed between patients with or without previously known or unknown thyroid dysfunction. EDE total and subscale scores in patients with known previous or current hypothyroidism and without TD are reported in Fig. 1. Patients who reported hypothyroidism showed significantly higher total and Shape Concern scores; no other significant difference was observed. EDE scores of patients without known previous or current TD, with TSH>4 mU/l, were not significantly different from those of subjects with normal thyroid function (Fig. 2).
Fig. 2. EDE total and subscale scores (median [quartiles]) in patients with TSH>4 mU/l (empty bars) and with TSH 4 mU/l (grey bars) among those without known previous or current thyroid disease. R = restriction, EC = eating concern, WC = weight concern, SC = shape concern.
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In the total sample, 14.4% of patients reported at least one episode of binge eating in the last month. The proportion of patients reporting binge eating was 15% (5/30) in those with previously known hypothyroidism, and 14% (32/223) in those without known TD ( p = ns). No significant difference in the number of eating binges in the last month was observed between the two groups.
4. Discussion A relatively high prevalence of known previous or current TD was found in the present sample. One possibility is that the previous hypothyroidism could have contributed to weight gain in some of the patients. It should also be considered that the Outpatient Clinic in which the patients were enrolled is part of the Unit of Endocrinology of the University Hospital, and obese patients with known thyroid disorders could be overrepresented in the sample. Among those who did not report previously known TD, a relevant proportion showed a TSH over the upper limit of the normal range, suggesting an existing hypothyroidism. The prevalence of previously unknown hypothyroidism was higher than that recently reported in a general population sample in Northern Italy (Rivolta et al., 1999). This difference could be due to the fact that the present sample is composed of obese individuals, in whom altered thyroid function could have contributed to weight gain. Furthermore, patients with unknown hypothyroidism could be more resistant to standard weight loss programs, and could therefore be more likely to refer to a specialized University Clinic. The prevalence of previously known or unknown hypothyroidism observed in the present study should not be considered representative of the total population of obese subjects, being probably in part the result of self-selection of patients at referral. However, the relevant proportion of subjects without a diagnosis of TD but with abnormal thyroid function suggests the usefulness of the determination of TSH for the routine screening of subclinical hypothyroidism in all obese patients seeking weight loss in specialized Outpatient Clinics. The prevalence of BED in the present sample was similar to that previously reported by our group in a similar setting (Ricca et al., 2000). Although previous studies have reported a much higher prevalence of BED in obese patients (Stunkard et al., 1996), differences in assessment methods and recruitment procedures could account for discrepancies in results (Varnado et al., 1997). Patients with known previous or current hypothyroidism showed a higher concern about body shape than the rest of the sample. This finding, consistent with previous reports (Hall et al., 1995; Tiller et al., 1994), suggests that TD could really affect attitudes toward shape, weight, or eating. It could be speculated that weight fluctuations at the onset of TD and at the initiation of treatment could focus the attention of patients’ attention of on body shape, determining the observed increase in EDE Shape Concern scores. An increased shape concern could, in turn, induce a greater restraint and eventually loss of control over eating, in susceptible individuals. This hypothesis deserves to be investigated through specifically
178
E. Mannucci et al. / Eating Behaviors 4 (2003) 173–179
designed studies assessing the weight history of obese patients with or without previous or current hypothyroidism. Thyroid disease is also associated with mood fluctuations, which could determine abnormalities in eating attitudes in some subjects; on the other hand, the occurrence of depressive symptoms could lead to a screening for thyroid dysfunction, and patients with affective disorders could therefore be more likely to receive a diagnosis of hypothyroidism. Furthermore, thyroid dysfunction has been reported to be associated with increased prevalence of general psychopathology, (Placidi et al., 1998), which could explain the observed differences in eating attitudes between subjects with and without hypothyroidism. The relatively small size of the present sample does not allow any multivariate analysis, adjusting differences in eating attitudes and behavior for mood depression and associated psychopathology. Studies on larger samples of obese patients, with an accurate assessment of other psychopathological domains as well as eating attitudes and behavior, are needed to clarify this point. Differences in eating attitudes could also theoretically be the consequence of altered levels of thyroid hormones. In fact, it is known that thyrotropin-releasing hormone (TRH), TSH, and thyroid hormones are involved in the regulation of eating behavior (Krotkiewski, 2000). However, in the present study, no difference in eating attitudes and behavior was observed between patients with or without previously unknown hypothyroidism. This suggests that the increased shape concern observed in subjects with known previous or current TD was not related to thyroid hormones blood levels. No difference in the prevalence of BED was observed between patients with or without a diagnosis of hypothyroidism. It is noteworthy that the small sample size could have prevented the detection of minor differences in prevalence. The only previous study of similar design, in which a difference in the prevalence of BED was observed, assessed ‘‘subclinical’’ or ‘‘subthreshold’’ eating disorders together with formal eating disorders defined by DSM-IV criteria (Tiller et al., 1994); this could explain the discrepancy in results. Furthermore, the present study, unlike previous investigations (Hall et al., 1995; Tiller et al., 1994), was performed in obese subjects, that could have shown a greater level of eating disturbances than the general population, irrespective of their thyroid status. Further studies on larger samples of lean and obese subjects are needed in order to verify eventual, small differences in the prevalence of eating disorders, and of BED in particular, among patients with or without TD. In conclusion, known previous or current hypothyroidism appears to be associated to higher body shape concern in obese individuals while previously unknown hypothyroidism, which was frequent in the sample studied, was not associated with any significant modification of eating attitudes and behavior. Thyroid disease could modify eating attitudes, although its effects on eating behavior need to be further investigated.
References American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders. 4th ed. (DSM-IV). Washington, DC: APA Press.
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