In the present paper, the investigation on the relationship of urinary hydroxyproline (HOP) excretion to growth and nutritional status has been carried out in Japanese school children, consisting of 518 boys and girls aged 9 to 15 years in the city and farming regions, and 33 boys aged 14-15 years in mountain villages.
The determination of urinary HOP was made by the method of Woessner.
Results: (1) A peak of HOP excretion by age was seen at 12 years of age for the boys and at 11 years of age for the girls in urban children, and those at 1.3 years of age for boys and 11 years of age for girls in rural children, respectively, and afterwards the HOP excretion fell rapidly in each group of children (Fig. 1).
The level of HOP excretion of urban children was higher till the age of 13 years in boys and up to the age of 11 years in girls as compared with rural children, and afterwards rural boys and girls maintained a slight higher level of HOP excretion than that of urban children (Fig. 2).
HOP excretion of boys aged 14-15 years in a mountain village was higher significantly as compared with urban and rural boys (Fig. 3).
These trends of the excretion of HOP by age, sex and regional groups well agreed with the curve of growth rate of Japanese children.
The correlationship between HOP excretion and serum alkaline phosphatase was seen with the correlation coefficients of 0.66-0.77 in 14-15 years old children (Table 2).
In the children aged of 9-10 years, significant correlations were seen between HOP/creatinine ratio and N/creatinine and UN/creatinine (Table 3).
The correlations of HOP/24h. to HOP/cr.×body-weight, HOP/cr.×body-height and HOP/cr. ratio showed the coefficients of 0.81, 0.75 and 0.70 respectively (Table 4). Discussion was made about that indices of HOP/cr.×wt. or HOP/cr.×ht. based on the random urine specimen could be used instead of HOP/24h., however the HOP/cr. ratio was useful for the evaluation of the growth activity.
