Skip to main content

Heart in Hypothyroidism

  • Chapter
  • First Online:
The Thyroid and Its Diseases

Abstract

The transition from the fetal to the adult phenotype heart depends on the increase in thyroid hormone (TH) in perinatal period (Liu and Gerdes, J Mol Cell Cardiol 22:1339–1348, 1990; Gerdes and Iervasi, Circulation 122:385–393, 2010). Moreover, T3 action is essential for preserving both cardiac morphology and performance in adult life because thyroid hormone controls the inotropic and lusitropic properties of the myocardium, cardiac growth, myocardial contractility, and vascular function (Liu and Gerdes, J Mol Cell Cardiol 22:1339–1348, 1990; Gerdes and Iervasi, Circulation 122:385–393, 2010; Fazio et al., Recent Prog Horm Res 59:31–50, 2002; Kahaly and Dillmann, Endocr Rev 26:704–728, 2005; Klein and Ojamaa, N Engl J Med 344:501–509, 2001; Biondi and Klein, Endocrine 24:1–13, 2004). Most patients with thyroid dysfunction experience cardiovascular (CV) manifestations, and the most serious complications of thyroid disease occur as a result of cardiac involvement (Fazio et al., Recent Prog Horm Res 59:31–50, 2002; Kahaly and Dillmann, Endocr Rev 26:704–728, 2005; Klein and Ojamaa, N Engl J Med 344:501–509, 2001; Biondi and Klein, Endocrine 24:1–13, 2004). Severe hypothyroidism or myxedema has a clinically relevant impact on the heart and on the cardiovascular system, and measurable changes in cardiovascular performance are detected even with small variations in thyroid hormone concentrations (Liu and Gerdes, J Mol Cell Cardiol 22:1339–1348, 1990; Gerdes and Iervasi, Circulation 122:385–393, 2010; Fazio et al., Recent Prog Horm Res 59:31–50, 2002; Kahaly and Dillmann, Endocr Rev 26:704–728, 2005; Klein and Ojamaa, N Engl J Med 344:501–509, 2001; Biondi and Klein, Endocrine 24:1–13, 2004).

Here we explore the hemodynamic alterations in overt and subclinical hypothyroidism (SHypo), their cardiovascular risks, the prevention and treatment of these disorders, and their cardiovascular complications.

This is a preview of subscription content, log in via an institution to check access.

Access this chapter

Chapter
USD 29.95
Price excludes VAT (USA)
  • Available as PDF
  • Read on any device
  • Instant download
  • Own it forever
eBook
USD 189.00
Price excludes VAT (USA)
  • Available as EPUB and PDF
  • Read on any device
  • Instant download
  • Own it forever
Hardcover Book
USD 249.99
Price excludes VAT (USA)
  • Durable hardcover edition
  • Dispatched in 3 to 5 business days
  • Free shipping worldwide - see info

Tax calculation will be finalised at checkout

Purchases are for personal use only

Institutional subscriptions

References

  1. Liu Z, Gerdes AM. Influence of hypothyroidism and the reversal of hypothyroidism on hemodynamics and cell size in the adult rat heart. J Mol Cell Cardiol. 1990;22:1339–48.

    Article  CAS  PubMed  Google Scholar 

  2. Gerdes AM, Iervasi G. Thyroid replacement therapy and heart failure. Circulation. 2010;122:385–93.

    Article  PubMed  Google Scholar 

  3. Fazio S, Palmieri EA, Lombardi G, Biondi B. Effects of thyroid hormone on the cardiovascular system. Recent Prog Horm Res. 2002;59:31–50.

    Article  Google Scholar 

  4. Kahaly GJ, Dillmann WH. Thyroid hormone action in the heart. Endocr Rev. 2005;26:704–28.

    Article  CAS  PubMed  Google Scholar 

  5. Klein I, Ojamaa K. Thyroid hormone and the cardiovascular system. N Engl J Med. 2001;344:501–9.

    Article  CAS  PubMed  Google Scholar 

  6. Biondi B, Klein I. Hypothyroidism as a risk factor for cardiovascular disease. Endocrine. 2004;24:1–13.

    Article  CAS  PubMed  Google Scholar 

  7. Buccino RA, Spann JF Jr, Pool PE, Sonnenblick EH, Braunwald E. Influence of the thyroid state on the intrinsic contractile properties and energy stores of the myocardium. J Clin Invest. 1967;46:1669–82.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. Crowley WF Jr, Ridgway EC, Bough EW, Francis GS, Daniels GH, Kourides IA, Myers GS, Maloof F. Noninvasive evaluation of cardiac function in hypothyroidism. Response to gradual thyroxine replacement. N Engl J Med. 1977;296:1–6.

    Article  PubMed  Google Scholar 

  9. Manns JJ, Shepherd AMM, J Crooks DG. Adamson measurement of cardiac muscle relaxation in hypothyroidism. Br Med J. 1976;1:1366–8.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  10. Santos AD, Miller RP, Mathew PK, Wallance WA, Cave WT, Hinojosa L. Echocardiographic characterization of the reversible cardiomyopathy of hypothyroidism. Am J Med. 1980;68:675–82.

    Article  CAS  PubMed  Google Scholar 

  11. Galderisi M, Vitale G, D’Errico A, Lupoli GA, Ciccarelli A, Cicala S, Pardo M, Lupoli G, de Divitiis O. Usefulness of pulsed tissue Doppler for the assessment of left ventricular myocardial function in overt hypothyroidism. Ital Heart. 2004;5:257–64.

    Google Scholar 

  12. Tielens E, Pillary M, Storm C, Berghout A. Changes in cardiac function at rest before and after treatment in primary hypothyroidism. Am J Cardiol. 2000;85:376–80.

    Article  CAS  PubMed  Google Scholar 

  13. Virtanen VK, Saha HH, Groundstroem KW, Salmi J, Pasternack AI. Thyroid hormone substitution therapy rapidly enhances left-ventricular diastolic function in hypothyroid patients. Cardiology. 2001;96:59–64.

    Article  CAS  PubMed  Google Scholar 

  14. Kahaly GJ, Kampmann C, Mohr-Kahaly S. Cardiovascular hemodynamics and exercise tolerance in thyroid disease. Thyroid. 2002;12:473–81.

    Article  PubMed  Google Scholar 

  15. Dernellis J, Panaretou M. Effects of thyroid replacement therapy on arterial blood pressure in patients with hypertension and hypothyroidism. Am Heart J. 2002;143:718–24.

    Article  CAS  PubMed  Google Scholar 

  16. Saito I, Ito K, Saruta T. Hypothyroidism as a cause of hypertension. Hypertension. 1983;5:112–5.

    Article  CAS  PubMed  Google Scholar 

  17. Fommei E, Iervasi G. The role of thyroid hormone in blood pressure homeostasis: evidence from short-term hypothyroidism in humans. J Clin Endocrinol Metab. 2002;87:1996–2000.

    Article  CAS  PubMed  Google Scholar 

  18. Bengel FM, Nekolla SG, Ibrahim T, Weniger C, Ziegler SI, Schwaiger M. Effect of thyroid hormones on cardiac function, geometry, and oxidative metabolism assessed noninvasively by positron emission tomography and magnetic resonance imaging. J Clin Endocrinol Metab. 2000;85:1822–7.

    Article  CAS  PubMed  Google Scholar 

  19. Iglesias P, Díez JJ. Thyroid dysfunction and kidney disease. Eur J Endocrinol. 2009;160:503–15.

    Article  CAS  PubMed  Google Scholar 

  20. Kinne R, De Santo NG. Effects of thyroid hormones on heart and kidney functions. Miner Electrolyte Metab. 1999;25:56–64.

    Article  PubMed  Google Scholar 

  21. Montenegro J, Gonzalez O, Saracho R, Aguirre R, Gonzalez O, Martinez I. Changes in renal function in primary hypothyroidism. Am J Kidney Dis. 1996;27:195–8.

    Article  CAS  PubMed  Google Scholar 

  22. Cappola AR, Ladenson PW. Hypothyroidism and atherosclerosis. J Clin Endocrinol Metab. 2003;88:2438–44.

    Article  CAS  PubMed  Google Scholar 

  23. Duntas LH. Thyroid disease and lipids. Thyroid. 2002;12:287–93.

    Article  CAS  PubMed  Google Scholar 

  24. Biondi B, Palmieri EA, Lombardi G, Fazio S. Subclinical hypothyroidism and cardiac function. Thyroid. 2002;12:505–10.

    Article  PubMed  Google Scholar 

  25. Biondi B, Palmieri EA, Lombardi G, Fazio S. Effects of subclinical thyroid dysfunction on the heart. Ann Intern Med. 2002;137:904–14.

    Article  PubMed  Google Scholar 

  26. Biondi B, Cooper DS. The clinical significance of subclinical thyroid dysfunction. Endocr Rev. 2008;29:76–131.

    Article  CAS  PubMed  Google Scholar 

  27. Biondi B, Cooper DS. Subclinical thyroid disease. Lancet. 2012;379:1142–54.

    Article  PubMed  Google Scholar 

  28. Biondi B. Cardiovascular effects of mild hypothyroidism. Thyroid. 2007;17:625–30.

    Article  CAS  PubMed  Google Scholar 

  29. Biondi B, Fazio S, Palmieri EA, Carella C, Panza N, Cittadini A, Bonè F, Lombardi G, Saccà L. Left ventricular diastolic dysfunction in patients with subclinical hypothyroidism. J Clin Endocrinol Metab. 1999;84:2064–7.

    Article  CAS  PubMed  Google Scholar 

  30. Mohr-Kahaly S, Beyer J, Meyer J. Left ventricular function analyzed by Doppler and echocardiographic methods in short-term hypothyroidism. Am J Cardiol. 1995;75:645–8.

    Article  PubMed  Google Scholar 

  31. Vitale G, Galderisi M, Lupoli GA, Celentano A, Pietropaolo I, Parenti N, de Divitis O, Lupoli G. Left ventricular myocardial impairment in subclinical hypothyroidism assessed by a new ultrasound tool: pulsed tissue Doppler. J Clin Endocrinol Metab. 2002;87:4350–5.

    Article  CAS  PubMed  Google Scholar 

  32. Ripoli A, Pingitore A, Favilli B, Bottoni A, Turchi S, Osman NF, De Marchi D, Lombardi M, L’Abbate A, Iervasi G. Does subclinical hypothyroidism affect cardiac pump performance? Evidence from a magnetic resonance imaging study. J Am Coll Cardiol. 2005;45:439–45.

    Article  PubMed  Google Scholar 

  33. Brenta G, Mutti LA, Schnitman M, Fretes O, Perrone A, Matute ML. Assessment of left ventricular diastolic function by radionuclide ventriculography at rest and exercise in subclinical hypothyroidism, and its response to L-thyroxine therapy. Am J Cardiol. 2003;91:1327–30.

    Article  CAS  PubMed  Google Scholar 

  34. Owen PJD, Rajiv C, Vinereanu D, Mathew T, Fraser AG, Lazarus JH. Subclinical hypothyroidism, arterial stiffness and myocardial reserve. J Clin Endocrinol Metab. 2006;9:2126–32.

    Article  Google Scholar 

  35. Nagasaki T, Inaba M, Kumeda Y, Hiura Y, Shirakawa K, Yamada S, Henmi Y, Ishimura E, Nishizawa Y. Increased pulse wave velocity in subclinical hypothyroidism. J Clin Endocrinol Metab. 2006;91:154–8.

    Article  CAS  PubMed  Google Scholar 

  36. Biondi B, Galderisi M, Pagano L, Sidiropulos M, Pulcrano M, D’Errico A, Ippolito S, Rossi A, de Divitiis O, Lombardi G. Endothelial-mediated coronary flow reserve in patients with mild thyroid hormone deficiency. Eur J Endocrinol. 2009;161:323–9.

    Article  CAS  PubMed  Google Scholar 

  37. Lekakis J, Papamichael C, Alevizaki M, Piperingos G, Marafelia P, Mantzos J, Stamatelopoulos S, Koutras DA. Flow-mediated, endothelium-dependent vasodilation is impaired in subjects with hypothyroidism, borderline hypothyroidism, and high-normal serum thyrotropin (TSH) values. Thyroid. 1997;7:411–4.

    Article  CAS  PubMed  Google Scholar 

  38. Danese MD, Ladenson PW, Meinert CL, Powe NR. Clinical review 115: effect of thyroxine therapy on serum lipoproteins in patients with mild thyroid failure: a quantitative review of the literature. J Clin Endocrinol Metab. 2000;85:2993–3001.

    CAS  PubMed  Google Scholar 

  39. Bakker SJ, ter Maaten JC, Popp-Snijders C, Slaets JP, Heine RJ, Gans RO. The relationship between thyrotropin and low density lipoprotein cholesterol is modified by insulin sensitivity in healthy euthyroid subjects. J Clin Endocrinol Metab. 2001;86:1206–11.

    CAS  PubMed  Google Scholar 

  40. Liu Y, Redetzke RA, Said S, Pottala JV, de Escobar GM, Gerdes AM. Serum thyroid hormone levels may not accurately reflect thyroid tissue levels and cardiac function in mild hypothyroidism. Am J Physiol Heart Circ Physiol. 2008;294:H2137–43.

    Article  CAS  PubMed  Google Scholar 

  41. Tang YD, Kuzman JA, Said S, Anderson BE, Wang X, Gerdes AM. Low thyroid function leads to cardiac atrophy with chamber dilatation, impaired myocardial blood flow, loss of arterioles, and severe systolic dysfunction. Circulation. 2005;112:3122–30.

    Article  CAS  PubMed  Google Scholar 

  42. Ladenson PW, Sherman SI, Baughman KL, Ray PE, Feldman AM. Reversible alterations in myocardial gene expression in a young man with dilated cardiomyopathy and hypothyroidism. Proc Natl Aca Sci USA. 1992;89:5251–5.

    Article  CAS  Google Scholar 

  43. Biondi B. Heart failure and thyroid dysfunction. Eur J Endocrinol. 2012;167:609–18.

    Article  CAS  PubMed  Google Scholar 

  44. Rodondi N, Bauer DC, Cappola AR, Cornuz J, Robbins J, Fried LP, Ladenson PW, Vittinghoff E, Gottdiener JS, Newman AB. Subclinical thyroid dysfunction, cardiac function, and the risk of heart failure. The cardiovascular health study. J Am Coll Cardiol. 2008;52:1152–9.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  45. Gencer B, Collet TH, Virgini V, Bauer DC, Gussekloo J, Cappola AR, Nanchen D, den Elzen WPJ, Balmer P, Luben RN, Iacoviello M, Triggiani V, Cornuz J, Newman AB, Khaw KT, Jukema JW, Westendorp RGJ, Vittinghoff E, Aujesky D, Rodondi N, Thyroid Studies Collaboration. Subclinical thyroid dysfunction and the risk of heart failure events: an individual participant data analysis from six prospective cohorts. Circulation. 2012;126:1040–9.

    Article  CAS  PubMed  Google Scholar 

  46. Iervasi G, Molinaro S, Landi P, Taddei MC, Galli E, Mariani F, L’Abbate A, Pingitore A. Association between increased mortality mortality and mild thyroid dysfunction in cardiac patients. Arch Intern Med. 2007;167:1526–32.

    Article  PubMed  Google Scholar 

  47. Iacoviello M, Guida P, Guastamacchia E, Triggiani V, Forleo C, Catanzaro R, Cicala M, Basile M, Sorrentino S, Favale S. Prognostic role of sub-clinical hypothyroidism in chronic heart failure outpatients. Curr Pharm Des. 2008;14:2686–92.

    Article  CAS  PubMed  Google Scholar 

  48. Silva-Tinoco R, Castillo-Martìnez L, Orea-Tejeda A, Orozco-Gutièrez JJ, Vàzquez-DÃaz O, Montanò-Hernàndez P, Flores-Rebollar A, Reza-Albarràn A. Developing thyroid disorders is associated with poor prognosis factors in patient with stable chronic heart failure. Int J Cardiol. 2011;147:e24–5.

    Article  PubMed  Google Scholar 

  49. Nanchen D, Gussekloo J, Westendorp RG, Stott DJ, Jukema JW, Trompet S, Ford I, Welsh P, Sattar N, Macfarlane PW, Mooijaart SP, Rodondi N, de Craen AJ, PROSPER Group. Subclinical thyroid dysfunction and the risk of heart failure in older persons at high cardiovascular risk. J Clin Endocrinol Metab. 2012;97:852–61.

    Article  CAS  PubMed  Google Scholar 

  50. Jessup M, Abraham WT, Casey DE, Feldman AM, Francis GS, Ganiats TG, Konstam MA, Mancini DM, Rahko PS, Silver MA, Stevenson LW, Yancy CW. 2009 focused update: ACCF/AHA guidelines for the diagnosis and Management of Heart Failure in adults: a report of the American College of Cardiology Foundation/American Heart Association task force on practice guidelines: developed in collaboration with the International Society for Heart and Lung Transplantation. Circulation. 1977–2016;200:119.

    Google Scholar 

  51. Kahaly GJ. Cardiovascular and atherogenic aspects of subclinical hypothyroidism. Thyroid. 2000;10:665–79.

    Article  CAS  PubMed  Google Scholar 

  52. Rodondi N, den Elzen WP, Bauer DC, Cappola AR, Razvi S, Walsh JP, Asvold BO, Iervasi G, Imaizumi M, Collet TH, Bremner A, Maisonneuve P, Sgarbi JA, Khaw KT, Vanderpump MP, Newman AB, Cornuz J, Franklyn JA, Westendorp RG, Vittinghoff E, Gussekloo J, Thyroid Studies Collaboration. Subclinical hypothyroidism and the risk of coronary heart disease and mortality. JAMA. 2010;304:1365–74.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  53. Schwimmer D, Vogel M, Mc Gavack TH. Clinical manifestations in forty cases of myxedema. J Clin Endocrinol Metab. 1947;7:468.

    CAS  PubMed  Google Scholar 

  54. Keating FRJ, Parkin TW, Selby JB, Dickinson LS. Treatment of heart disease associated with myxedema. Prog Cardiovasc Dis. 1961;3:364–81.

    Article  PubMed  Google Scholar 

  55. Ladenson PW, Levin AA, Ridgway EC, Daniels GH. Worsening of angina, myocardial infarction and death can occur when L-thyroxine therapy is started with a full dose in older patients with ischemic heart disease. Am J Med. 1984;77:261–6.

    Article  CAS  PubMed  Google Scholar 

  56. Biondi B, Wartofsky L. Treatment with thyroid hormone. Endocr Rev. 2014;35:433–512.

    Article  CAS  PubMed  Google Scholar 

  57. Monzani F, Di Bello V, Caraccio N, Bertini A, Giorgi D, Giusti C, Ferranini E. Effect of levothyroxine on cardiac function and structure in subclinical hypothyroidism: a double blind, placebo-controlled study. J Clin Endocrinol Metab. 2001;86:1110–5.

    Article  CAS  PubMed  Google Scholar 

  58. Yazici M, Gorgulu S, Sertbas Y, Erbilen E, Albayrak S, Yildiz O, Uyan C. Effects of thyroxin therapy on cardiac function in patients with subclinical hypothyroidism: index of myocardial performance in the evaluation of left ventricular function. Int J Cardiol. 2004;95:135–43.

    Article  PubMed  Google Scholar 

  59. Taddei S, Caraccio N, Virdis A, Dardano A, Versari D, Ghiadoni L, Salvetti A, Ferrannini E, Monzani F. Impaired endothelium-dependent vasodilatation in subclinical hypothyroidism: beneficial effect of levothyroxine therapy. J Clin Endocrinol Metab. 2003;88:3731–7.

    Article  CAS  PubMed  Google Scholar 

  60. Monzani F, Caraccio N, Kozakowa M, Dardano A, Vittone F, Virdis A, Taddei S, Palombo C, Ferrannini E. Effect of levothyroxine replacement on lipid profile and intima-media thickness in subclinical hypothyroidism: a double-blind, placebo- controlled study. J Clin Endocrinol Metab. 2004;89:2099–106.

    Article  CAS  PubMed  Google Scholar 

  61. Nagasaki T, Inaba M, Henmi Y, Kumeda Y, Ueda M, Tahara H, Sugiguchi S, Fujiwara S, Emoto M, Ishimura E, Onoda N, Ishikawa T, Nishizawa Y. Decrease in carotid intima-media thickness in hypothyroid patients after normalization of thyroid function. Clin Endocrinol. 2003;59:607–12.

    Article  CAS  Google Scholar 

  62. Razvi S, Ingoe L, Keeka G, Oates C, McMillan C, Weaver JU. The beneficial effect of L-thyroxine on cardiovascular risk factors, endothelial function, and quality of life in subclinical hypothyroidism: randomized, crossover trial. J Clin Endocrinol Metab. 2007;92:1715–23.

    Article  CAS  PubMed  Google Scholar 

  63. Villar HC, Saconato H, Valente O, Atallah AN. Thyroid hormone replacement for subclinical hypothyroidism. Cochrane Database Syst Rev. 2007;CD003419.

    Google Scholar 

  64. Razvi S, Weaver JU, Vanderpump MP, Pearce SH. The incidence of ischemic heart disease and mortality in people with subclinical hypothyroidism: reanalysis of the Whickham survey cohort. J Clin Endocrinol Metab. 2010;95:1734–40.

    Article  CAS  PubMed  Google Scholar 

  65. Razvi S, Weaver JU, Butler TJ, Pearce SH. Levothyroxine treatment of subclinical hypothyroidism, fatal and nonfatal cardiovascular events, and mortality. Arch Intern Med. 2012;72(10):811–7.

    Google Scholar 

  66. Ochs N, Auer R, Bauer DC, Nanchen D, Gussekloo J, Cornuz J, Rodondi N. Meta-analysis: subclinicalthyroid dysfunction and the risk for coronary heart disease and mortality. Ann Intern Med. 2008;148:832–45.

    Article  PubMed  Google Scholar 

  67. Razvi S, Shakoor A, Vanderpump M, Weaver JU, Pearce SH. The influence of age on the relationship between subclinical hypothyroidism and ischemic heart disease: a metaanalysis. J Clin Endocrinol Metab. 2008;93:2998–3007.

    Article  CAS  PubMed  Google Scholar 

  68. Atzmon G, Barzilai N, Hollowell JG, Surks MI, Gabriely I. Extreme longevity is associated with increased serum thyrotropin. J Clin Endocrinol Metab. 2009;94:1251–4.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  69. Gussekloo J, van Exel E, de Craen AJ, Meinders AE, Frölich M, Westendorp RG. Thyroid status, disability and cognitive function, and survival in old age. JAMA. 2004;292:2591–9.

    Article  CAS  PubMed  Google Scholar 

  70. Waring AC, Arnold AM, Newman AB, Bùzková P, Hirsch C, Cappola AR. Longitudinal changes in thyroid function in the oldest old and survival: the cardiovascular health study all-stars study. J Clin Endocrinol Metab. 2012;97:3944–50.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  71. Somwaru LL, Arnold AM, Joshi N, Fried LP, Cappola AR. High frequency of and factors associated with thyroid hormone over-replacement and under-replacement in men and women aged 65 and over. J Clin Endocrinol Metab. 2009;94:1342–5.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  72. Cappola AR, Fried LP, Arnold AM, Danese MD, Kuller LH, Burke GL, Tracy RP, Ladenson PW. Thyroid status, cardiovascular risk, and mortality in older adults. JAMA. 2006;295:1033–41.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Bernadette Biondi .

Editor information

Editors and Affiliations

Rights and permissions

Reprints and permissions

Copyright information

© 2019 Springer International Publishing AG, part of Springer Nature

About this chapter

Check for updates. Verify currency and authenticity via CrossMark

Cite this chapter

Biondi, B., Kahaly, G.J. (2019). Heart in Hypothyroidism. In: Luster, M., Duntas, L., Wartofsky, L. (eds) The Thyroid and Its Diseases. Springer, Cham. https://doi.org/10.1007/978-3-319-72102-6_21

Download citation

  • DOI: https://doi.org/10.1007/978-3-319-72102-6_21

  • Published:

  • Publisher Name: Springer, Cham

  • Print ISBN: 978-3-319-72100-2

  • Online ISBN: 978-3-319-72102-6

  • eBook Packages: MedicineMedicine (R0)

Publish with us

Policies and ethics