CATCH-UP GROWTH DURING ADOLESCENCE

Various chronic diseases and malnutrition cause growth failure in childhood and adolescence; following recovery, catch-up growth may occur. The extent to which growth failure can be compensated for depends on the timing, severity and duration of the growth failure, as well as on the aetiology and pathogenesis of the disease restricting growth and development. There are three types of catch-up growth. In type 1, when growth restriction ceases, growth occurs to such an extent that the height deficit is rapidly eliminated. Once the original growth curve is attained, growth proceeds normally. In type 2, when growth restriction ceases, there is a delay in growth and somatic development. However, growth continues for longer than usual, compensating for the growth arrest. Type 3 is a mixture of types 1 and 2, and all three types may be complete or incomplete. Two factors make it difficult to record catch-up growth during adolescence: the large variability in timing, expression and duration of pubertal growth and somatic development, and the relationship between the measurement error and the increase in growth observed within a defined time period. To avoid data collection and analysis problems, prospective and long-term study design should be considered. Ideally, data collection should be started in the prepubertal period and continue until final adult height is reached. High technical standards and well-trained personnel should be used. A variety of parameters should be assessed to obtain different dimensions of the growth process and pubertal development. Data analysis should be related not only to chronological age, but also to biologically oriented time-scales, such as bone age, pubertal staging and age at peak height velocity.