Wang-Wei Cai, MD Department of Biochemistry and Molecular Biology, Hainan Medical College, Haikou, China Qing-Peng Kong, PhD State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China KIZ/CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming, China ACKNOWLEDGMENTS Conflict of Interest: The authors declare that they have no conflict of interest related to this manuscript. The study was supported by grants from National Basic Research Program of China (2013CB530802), Yun- nan Province (2011FA024, 2013FB069), Chinese Academy of Sciences, Natural Science Foundation of China (31322029, 31460290), and Department of Science and Technology of Hainan Province (KJHZ2013–16). Author Contributions: Kong, Cai: study concept and design. He, Chen, Yan, Xiao, Liu, Lin, Liao: acquisition of subjects and data, data analysis and interpretation, manu- script preparation. Sponsor’s Role: None. REFERENCES 1. Bremner AP, Feddema P, Leedman PJ et al. Age-related changes in thyroid function: A longitudinal study of a community-based cohort. J Clin Endo- crinol Metab 2012;97:1554–1562. 2. Atzmon G, Barzilai N, Hollowell JG et al. Extreme longevity is associated with increased serum thyrotropin. J Clin Endocrinol Metab 2009;94:1251– 1254. 3. Atzmon G, Barzilai N, Surks MI et al. Genetic predisposition to elevated serum thyrotropin is associated with exceptional longevity. J Clin Endocri- nol Metab 2009;94:4768–4775. 4. Rozing MP, Houwing-Duistermaat JJ, Slagboom PE et al. Familial longev- ity is associated with decreased thyroid function. J Clin Endocrinol Metab 2010;95:4979–4984. 5. Kabadi UM, Rosman PM. Thyroid hormone indices in adult healthy sub- jects: No influence of aging. J Am Geriatr Soc 1988;36:312–316. 6. Magri F, Muzzoni B, Cravello L et al. Thyroid function in physiological aging and in centenarians: Possible relationships with some nutritional markers. Metabolism 2002;51:105–109. 7. Mariotti S, Barbesino G, Caturegli P et al. Complex alteration of thyroid func- tion in healthy centenarians. J Clin Endocrinol Metab 1993;77:1130–1134. 8. Hansen PS, Brix TH, Sorensen TI et al. Major genetic influence on the reg- ulation of the pituitary-thyroid axis: A study of healthy Danish twins. J Clin Endocrinol Metab 2004;89:1181–1187. 9. He YH, Zhang YX, Yang LQ et al. Assessment of the health status of cen- tenarians in the south of China: A cross-sectional study. J Am Geriatr Soc 2014;62:1402–1404. 10. Ravaglia G, Forti P, Maioli F et al. Blood micronutrient and thyroid hor- mone concentrations in the oldest-old. J Clin Endocrinol Metab 2000;85:2260–2265. WORK AND OTHER ACTIVITIES IN RETIREMENT To the Editor: Defining “retirement” presents a challenge, with the use of a single word likely to oversimplify a com- plex reality. Decades ago, the broad consensus was that retirement represented a distinct stage in the life course at which point a person gave up “productive work.” 1 This was contingent on surviving long enough to enter retire- ment and not being “too worn out to enjoy anything that might follow.” 2 With longer life expectancy, distinctions between work and retirement are becoming less clear. Primary life- style choices facing older adults as they age can include full- or part-time work, further education, volunteer work, caring responsibilities, and other productive and social activities, as well as increased opportunities for leisure and hobbies. 3–5 Many of these choices involve some level of work. At a time when the “virtue” of self-reliance during retirement is encouraged, long-held normative assumptions about time use in retirement deserve attention. The aim of this study was to provide a snapshot of how self-identified fully and partially retired men and women aged 55 to 84 characterize their time. METHODS This study analyzed data from participants who said they were fully or partially retired on their baseline survey in the Sax Institute’s 45 and Up Study (Australia). 6 Partici- pants were asked “What is your current work status?” with non-mutually exclusive response options including fully retired, partially retired, performing full-time paid work, performing part-time paid work, being self- employed, performing unpaid work, studying, looking after family member or home, being unemployed, and being disabled or sick. Participants were also asked about other activities such as volunteer work; meetings of social clubs, religious groups, or other groups; and providing reg- ular care for a sick or disabled family member or friend. The 45 and Up Study has ethics approval from the Univer- sity of New South Wales human research ethics commit- tee. Cross-tabulations were conducted between work status and other activities to identify what men and women were doing during their “retirement.” Results are presented here for men and women in two age groups (55–69, 70–84). RESULTS One hundred six thousand seven hundred eighty-six indi- viduals completed the baseline survey from 2005 to 2009; 50.3% of men and 51.3% of women said they were fully retired, and 9.2% of men and 5.8% of women said they were partially retired. The men had a mean age of 63.8 and the women 61.8. Many of the fully retired partici- pants were engaged in unpaid or voluntary work. Partially retired participants were engaged in part-time or unpaid work or were self-employed (Table 1). Women were more likely than men to report looking after home or family and providing regular care for sick or disabled family members or friends, regardless of age and retirement sta- tus, although men and women were equally likely to care for a sick or disabled family member or friend. More than half of the participants reported going to social clubs, reli- gious clubs, or other groups, and approximately 40% were doing volunteer work. 1476 LETTERS TO THE EDITOR JULY 2015–VOL. 63, NO. 7 JAGS