205- How to decide whether bone age is significantly advanced over chronological
age or not?
In the above-said child, chronological age was 5 years and bone age was
6.5 years. From the table given below, it can be seen that at the age of 5 years,
1SD for bone age is 8.6 months for girls. A bone age >2.5 SD above chrono-
logical age is considered as significantly advanced.
i.e., 2.5 SD is 8.6 × 2.5 = 21.5 months = 1.79 years
Patient’s chronological age + 2.5 SD = 5 years +1.79 year = 6.79 years
Since the child’s bone age was 6.5 years (<2.5 SD advancement over chron-
ological age), it was not considered significant.
The table given below shows standard deviation for bone age at various
chronological ages in boys and girls from age of 1 year to 17 years.
Age (months) Boys SD (months) Girls SD (months)
12 2.1 2.7
18 2.7 3.4
24 4 4
30 5.4 4.8
36 6 5.6
42 6.6 5.5
48 7 7.2
54 7.8 8
60 8.4 8.6
66 9.1 8.9
72 9.3 9
84 10.1 8.3
96 10.8 8.8
108 11 9.3
120 11.4 10.8
132 10.5 12.3
144 10.4 14
156 11.1 14.6
168 12 12.6
180 14 11.2
192 15 15
204 15.4 15.4
With permission from Gilsanz V, Ratib O. Hand bone age. Berlin: Springer; 2005.
- How to treat a child with idiopathic GDPP?
Aim of treatment in a child with idiopathic GDPP is to herald the progression of
secondary sexual characteristics, prevent adverse psychosocial consequences,6 Precocious Puberty