ABSTRACT
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.