Table 2.

Important terminology used when assessing bone. The terminology used when assessing bone. Important distinctions are made between BMC and BMD. The definitions of areal BMD and BMAD ensure that the limitations of DXA scanning in growth-stunted children with CKD are accounted for

Terminology	Definition, units and description
Bone mineral content (BMC)	The amount of mineral found in an area of bone. Calcium is the predominant mineral found in bone. Measured in grams (g)
Bone mineral density (BMD)	Mass of mineral per unit volume of bone This reflects the ratio of bone mass to bone volume. Referred to as cortBMD for the bone cortex and trabBMD for the trabecular bone The ratio of BMC over bone size and thus expressed in g/cm3. BMD has been used interchangeably with areal BMD in the literature.
Areal bone mineral density (areal BMD)	A term used within DXA reporting. Mineral mass of the bone, divided by projection area of the X-rays (BMC/BA). The commonest parameter used in assessing bone. Represents a composite of bone size and mass Expressed in g/cm2
Bone mineral apparent density (BMAD)	BMAD is obtained by dividing the BMC by the estimated three-dimensional bone volume derived from its two dimensional projected bone area. This is done in children to account for growth and size in assessing bone density. For example, the lumbar spine is assumed to be of cylindrical or cuboidal shape in children when calculating BMAD.