I also have heard that bone age xrays are  very subjective. My son’s 3 year bone age was read by a radiologist and 2 ped. endos. Their interpretations were were bone age of 2 yrs 8 months, 3 years and 4 years.  I was very curious as to how they could get such different reads.

One of his docs was very accomodating. She brought out her Mayo Clinic bone xray book and showed me the various pictures (xrays in the book). To "read" the xray, they essentially compare spaces between the bones on your child’s xray to the spaces between the bones on the standard xrays in the book. It is extremely subjective, and I thought very hard to see any difference. The space between hand bones in a 2 yr old and hand bones in a 2 1/2 year old could not have been more than a few millimeters.

This same doc. also told me she really didn’t like to do bone age xrays before 2 or 3 years of age because the standards were not very good at that age and it was very difficult to give an accurate read.

I think you could have others read the xray and get very different results. Personally, I wouldn’t be concerned about 6 months unless you had other signs of undersuppression such as increased growth velocity.