Stunting and the Prediction of Lung Volumes Among Tibetan Children and Adolescents at High Altitude

Abstract

Weitz, Charles A., and Ralph M. Garruto. Stunting and the prediction of lung volumes among Tibetan children and adolescents at high altitude. High Alt Biol Med 16: [306][307][308][309][310][311][312][313][314][315][316][317] 2015.-This study examines the extent to which stunting (height-for-age Z-scores £ -2) compromises the use of low altitude prediction equations to gauge the general increase in lung volumes during growth among high altitude populations. The forced vital capacity (FVC) and forced expiratory volume (FEV 1 ) of 208 stunted and 365 non-stunted high-altitude Tibetan children and adolescents between the ages of 6 and 20 years are predicted using the Third National Health and Nutrition Examination Survey (NHANESIII) and the Global Lung Function Initiative (GLF) equations, and compared to observed lung volumes. Stunted Tibetan children show smaller positive deviations from both NHANESIII and GLF prediction equations at most ages than non-stunted children. Deviations from predictions do not correspond to differences in body proportions (sitting heights and chest circumferences relative to stature) between stunted and non-stunted children; but appear compatible with the effects of retarded growth and lung maturation that are likely to exist among stunted children. These results indicate that, before low altitude standards can be used to evaluate the effects of hypoxia, or before high altitude populations can be compared to any other group, it is necessary to assess the relative proportion of stunted children in the samples. If the proportion of stunted children in a high altitude population differs significantly from the proportion in the comparison group, lung function comparisons are unlikely to yield an accurate assessment of the hypoxia effect. The best solution to this problem is to (1) use stature and lung function standards based on the same low altitude population; and (2) assess the hypoxic effect by comparing observed and predicted values among high altitude children whose statures are most like those of children on whom the low altitude spirometric standard is based-preferably high altitude children with HAZ-scores ‡ -1.

Low lung function in the developing world is analogous to stunting: a review of the evidence

“…Stunting influenced deviations from predicted lung function values among 208 stunted and 365 non-stunted children in Tibet. These differences were compatible with the effects of retarded growth and lung maturation characteristic among stunted children 19 .…”

“…The effect of stunted height on lung function growth is further compounded by maturational delays, particularly during the onset of adolescent growth spurt in stature. During puberty, dysynaptic growth appears to be more conspicuous in stunted children as compared to normal children, as stunted children are not only shorter but also more likely to exhibit delayed increment in muscular strength and lung maturation 19 , 65 , 66 . However, while the phenotypic correlates of stunting recede due to rapid catch up growth during early childhood, indicators of restrictive lung function persist late into the life course.…”

Spatial and demographic disparities in short stature among school children aged 7–18 years: a nation-wide survey in China, 2014

“…The prevalence of short stature will be overestimated. The solutions for this are to build growth reference based on the same area population or lower the cut-off value to diagnose short stature in these places 48. We must be more prudent when we diagnose short stature of children from these areas and avoid excessive laboratory tests or therapy for these children.…”

Education, Altitude, and Humidity Can Interactively Explain Spatial Discrepancy and Predict Short Stature in 213,795 Chinese School Children

“…Our study indicated that children who lived in high-altitude places had a high risk of short stature, which generally applied to other individuals residing in such areas—Peruvians and Tibetans (2, 20), who live in the Andes and Himalayas, respectively, with an average elevation above 4,000 m. Another study focused on the growth retardation of children aged 0–36 months in Tibet showed that with an increase in altitude (3,000 to 4,500 m), the prevalence and odds ratio of stunting gradation increased—this phenomenon was not observed in underweight and wasting (42). This result was also confirmed by studies involving children in Argentina and other countries (43, 44), and may be partly attributed to the negative correlation between birth weight and altitude, where intrauterine growth restrictions result in oxygen deficit and the effect of cytokines, endothelin, etc.…”