Original Article Bone Speed of Sound Throughout Lifetime Assessed With Quantitative Ultrasound in a Mexican Population Rodolfo Rivas-Ruiz, 1,2 Patricia Clark, * ,1 Juan O. Talavera, 2,3 Gerardo Huitr on, 3 Juan A. Tamayo, 4 and Jorge Salmer on 5 1 Hospital Infantil de M exico, Federico G omez-Facultad de Medicina, Universidad Nacional Aut onoma de M exico, M exico City, D.F., M exico; 2 Centro M edico Nacional S, XXI, Instituto Mexicano del Seguro Social, M exico, D.F., M exico; 3 Centro de Investigaci on en Ciencias M edicas, Universidad Aut onoma del Estado de M exico, Toluca, M exico; 4 Comit e Mexicano para la Prevenci on de la Osteoporosis, A.C., M exico, D.F., M exico; and 5 Unidad de Investigaci on Epidemiol ogica y en Servicios de Salud, Instituto Mexicano del Seguro Social, Cuernavaca, Morelos, M exico and Centro de Investigaci on de Salud Poblacional, Instituto Nacional de Salud P ublica, Cuernavaca, Morelos, M exico Abstract The purpose of this study was to assess the bone speed of sound (SoS) through lifetime of a large Mexican pop- ulation sample by determining the SoS from the radius and tibia using quantitative ultrasound (QUS). This is a cross- sectional evaluation of participants in the Mexican Health Workers Cohort Study. QUS measurements were performed using Sunlight Omnisense 8000P; Z- and T-scores were calculated for both sexes at the distal third of the radius and midshaft tibia, both on the nondominant side. A locally weighted regression smoothing scatterplot model was used to identify different phases of bone accretion and loss. A total of 9128 participants aged 1e75 yr were measured with QUS. Bone SoS accretion began 5 yr earlier in girls than boys ( p ! 0.05). Maximal SoS or peak bone SoS was noted at 28 yr in the radius and at 22 yr in the tibia. Postmenopausal women (45e50 yr) showed significant SOS decrease at both sites ( p ! 0.05) compared with men. Using the locally weighted regression smoothing scatterplot model, we found 5 different phases that constitute the biological development of bone over the life course, from ages 1e6, 7e12, 12e25, 25e50, and 50e75 yr ( p ! 0.05). Our study shows the age- and sex-dependent changes and different phases of bone development expressed by SoS measurements of the radius and tibia. The values reported in this study can be used as a reference for urban Mexican population. Key Words: Bone health; osteoporosis; quantitative ultrasound; reference values. Background Osteoporosis and fragility fractures are a widespread public health problem, and Mexico is not the exception (1). The quality of life consequences and high costs of treat- ing fractures make osteoporosis a clear focus for clinical research, with growing interest in developing new methods for screening and assessing bone health (2,3). Dual-energy X-ray absorptiometry (DXA) is the gold standard for bone assessment and has been used widely over the last 25 yr to determine bone mineral density (BMD) at various anatomical sites. This technology has also been used for early detection of individuals at high risk of osteoporotic fractures (4). Yet despite the proven efficacy of DXA, it is not widely available. According to a recent Latin America audit, in Mexico, there are only 1.8e2.3 DXAs per million individuals aged 50 yr and older (5). An alternative technology for measuring bone density is quantitative ultrasound (QUS), a diagnostic method that mea- sures the speed of sound (SoS) in bone. QUS has the advan- tages of being free of radiation, easy to use, portable, and lower in cost than DXA (6). It has also been suggested that QUS may identify aspects of bone quality not captured by Received 05/28/13; Revised 09/27/13; Accepted 11/01/13. *Address correspondence to: Patricia Clark, MD, PhD, DSc, Fed- erico G omez-Facultad de Medicina, Universidad Nacional Aut onoma de M exico, Hospital Infantil de M exico, 06720 Mexico City, Mexico. E-mail: patriciaclarkmx@gmail.com 1 Journal of Clinical Densitometry: Assessment & Management of Musculoskeletal Health, vol. -, no. -,1e8, 2014 Ó Copyright 2014 by The International Society for Clinical Densitometry 1094-6950/-:1e8/$36.00 http://dx.doi.org/10.1016/j.jocd.2013.11.002