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Background: Daily changes in height have been found to be a non-linear process. Its exact pattern is still controversial. In previous studies on 34 healthy children aged 0.32-12.99 years, we found that growth is a tri-phasic process: stasis, steep changes (or saltation) and continuous growth. There is very little information in the literature about daily changes in head circumference., Aim: The present study analysed growth in head circumference and supine length in eight healthy infants., Subject and Methods: Supine length and head circumference was measured five times a week during 151 days. Mean intra-observer technical error of measurement (TEM) for head circumference and supine length were 0.10 and 0.15 cm, respectively; smoothing techniques used were based on the TEM with a hard rejection criterion., Results: The three types of events previously found in supine length are also present in head circumference. The number of steep changes was greater in supine length than in head circumference., Conclusion: Growth is a discontinuous and irregular process, present not only in long bones but also in skull bones. Although long-term growth curves of head circumference and supine length are different, when measured on a daily basis findings suggest that skull and long bones have a common pattern; the physiological basis needs future research.

Background: Relative macrocephaly describes a large head in relation to stature, and this indicator could be helpful in depicting syndromes with large heads and short stature, providing the existence of some relationship between both measurements in normal children., Objective: The aims of this study were (1) to evaluate the existence of a relationship between head circumference (HC), height and weight, (2) to build an instrument for evaluating it and validate its clinical utility., Subjects and Methods: Relationship between HC, height and weight was explored in a national sample of 3571 healthy, well nourished boys and girls aged 0-5.99 years. Age-adjusted correlation coefficients calculated were: HC and height, 0.30; HC and weight, 0.37; and height and weight, 0.60. A growth standard of HC to height ratio was constructed using the LMS method with both sexes pooled, and selected centiles and SD scores of HC to height ratio for each age were estimated. Z-scores of HC for age, and HC to height ratio were calculated for 13 children with hypochondroplasia, and 90 with achondroplasia, both conditions associated with macrocephaly., Results: Only four children with hypochondroplasia had HC for age above 2.00 SD, whereas all of them showed SD scores above 2.00 when the HC to height ratio was evaluated. Results suggest that the prepared standard may be of clinical utility., Conclusions: A new standard is proposed, capable of pinpointing children with relative macrocephaly.

Background: There is agreement amongst most investigators now on the fact that growth, when measured over short periods, is an irregular and non-linear process. However, many aspects related to this process still remain controversial, for example, the continuity or discontinuity of the daily changes and the degree of existence of age differences in growth patterns., Aim: In this study we analyse and compare growth in height based on daily measurements in three samples of healthy children: Eight infants (I), 16 schoolchildren (S) and 10 adolescent girls during their pubertal growth spurt (A)., Subjects and Methods: Standing height or supine length were measured five times a week during 128 days, with Harpenden instruments and standardized techniques. A jump-preserving smoothing technique, based on the technical error of measurement (TEM) with a hard rejection criterion was used to analyse our data. TEM varied between 0.08 and 0.20 cm., Results: Three types of events were found: (1) stasis (changes in smoothed values indistinguishable from zero over 7 or more consecutive days), (2) steep changes (any daily increment greater than 0.3 cm over 1 day), and (3) continuous growth (small, and continued increments over time). The three types were present in all infants, adolescents and schoolchildren, with the exception of four schoolchildren who did not show steep changes. In the three samples, steep changes accounted for 32.7% (r = 15.3-54.5%) of the total growth during the study period. Mean numbers of 1-day steep changes were 4.4, 1.4 and 2.1 for samples I, S and A, respectively. Mean numbers of stasis periods were 3.0, 2.9 and 4.3 for samples I, S and A, respectively. The longest stasis period observed was 28 consecutive days in one infant and one school child. Mean number of steep changes per child was significantly greater in infants., Conclusion: Our findings support the concept of growth as a non-linear and irregular process with three phenomena: Stasis, steep changes and continuous growth present in all ages, including infancy, school age and adolescence.

Hypochondroplasia (HCH) is a skeletal dysplasia characterized by short stature with disproportionately short arms and legs. Anthopometrics and skeletal features are very similar to achondroplasia but milder. Seventy per cent of affected individuals are heterozygous for a mutation of the FGFR3 gene. Differences in some anthropometric measurements in affected patients with and without N540K mutation were analysed. Diagnosis of the disease was made on the presence of previously standardized criteria: short stature, short limbs and three or more X-ray features. Genomic DNA was extracted from peripheral blood leukocytes by standard procedures. PCR amplification of exons 10, 13 and 15 of FGFR3 was performed. Twenty-six patients were studied (median age was 7.31, range 0.27-20.0 years). Sitting height, body proportions and head circumference (HC) were statistically different in the mutated group. Receiver Operating Characteristic (ROC) analysis was carried out in order to estimate the discriminating power of different cut-off points of HC for recognizing patients with and without the mutation. A figure of 1.86 SD for HC was found to have a sensitivity of 73.3% and specificity of 100% for detecting HCH patients with the mutation. All of them had a HC greater than 1.86?SD. These results contribute to a better characterization of the clinical-molecular relationships in HCH.