I do not known of many methods for analyzing body composition of children under age 15. However,here is 1 device that will work.

There is a tanita body composition analyzer for children under 17

hope this helps

http://www.tanita.com/en/sc-331s/

Akern devices works with specific equations for BiaVector for children below 14 years of age

Hi

The following papers validated bioimpedance against DXA in typically developing children. You may check the reference of the analysers used and validated in these papers:

Gutin B, Litaker M, Islam S, Manos T, Smith C, Treiber F.

Body-composition measurement in 9–11-year-old children by

dual-energy-X-ray absorptiometry, skin-fold-thickness measurements,

and bio-impedance analysis. Am J Clin Nutr

1996;63:287–92.

Van den Broeck J, Witt JM. Anthropometry and body

composition in children. Horm Res 1997;48(Suppl 1):33–42.

Guo S, Roche AF, Houtkooper L. Fat-free mass in children

and young adults predicted from bioelectric impedance and

anthropometric variables. Am J Clin Nutr 1989;50:435–43.

Houtkooper LB, Going SB, Lohman TG, Roche AF, Van Loan M.

Bioelectrical impedance estimation of fat-free mass in

children and youth : a cross validation study. J Appl Physiol

1992;72:366–73.

Goran MI, Driscoll P, Johnson R, Nagy TR, Hunter G. Cross

calibration of body composition techniques against dualenergy-

X-ray absorptiometry in young children. Am J Clin

Nutr 1996;63:299–305.

Kubo et al. used a Tanita MC-190 for analyzing body composition of children between 6 an 11:

Kubo T et al. (2010): Evaluation of partial body composition using bioelectrical impedance in Japanese children. Asia Pac J Clin Nutr 2010;19 (4):594-601

I'm not sure what your budget is, but the bod pod works well for children. They have a pediatric version too.

http://www.bodpod.com/en/products/body-composition/adult-children-bod-pod-gs

http://www.bodpod.com/en/products/related-products/options/bod-pod-pediatric-option

The choice will depend on your budget and the amount of samples you need to measure and the required accuracy/precision. (As usual :P)

If your budget is low and you require low accuracy I would suggest BIA/DEXA/skin fold

If you have bigger budget and require more accuracy I would go for isotope dilution (perhaps combine with DLW) or underwater weighing (http://www-rohan.sdsu.edu/~ens304l/uww.htm) , the latter is the gold standard for body composition measurements. Stable isotope dilution method (both 2H and 18O) will give you an estimate of total body water. By knowing the hydration factor of lean body mass, (around 0.73) you can calculate the rest of the components (i.e. fat mass and lean body mass).

Body composition analysers by EchoMRI can measure fat mass, lean mass, fat free mass and total body water for children below 15 years of age.

(http://www.ncbi.nlm.nih.gov/pubmed/21779094)

Article Quantitative Nuclear Magnetic Resonance to Measure Fat Mass ...

The BIA 101 can be used from 2 to 85 years and performs alla BIVA .

You should download the software from www.akern.com that will run freely for 30 days evaluation

Bia 101 is a resistance and Reactance device. You need both for BIVA.

We are working with the "Data-Input GmbH( Darmstadt, Germany)" and we are using the program " Nutri Plus" . It is well evalueted with thousends of people and you can use it from 3 years up to any age.

It is working with BIA and BIVA interpretation ( percentiles) and it is very easy to handle and to learn.

For more information you should contact the Data input company in Germany.

Sorry for my bad english and I hope I could help yoe

As others have mentioned, there are various techniques available that have published regression equations specifically for children. The usefulness of these depends on the research that went into developing the equations in the first place...look for evidence that the manufacturer has utilized sound scientific principles in the development of their equations. There are equations available for estimating %fat from skinfolds (e.g.Slaughter MH, Lohman TG, Boileau RA, Horswill CA, Stillman RJ, Van Loan MD, Bemben DA. 1988. Skinfold equations for estimation of body fatness in children and youth. Hum Biol 60:709–723.). There are also techniques available to adjust body density measures obtained from densitometric techniques to in part, account for different levels of chemical maturity. (adjustments to FFBdensity based on height for example).

In addition to preceding comments, be very aware of the 95% limits of agreement for your choice of method.  While many studies reports no methodological difference between group means, the individual variation can be enormous for children.  Much of the individual variation has to do with the physical maturity level of the child, their activity level, and race/ethnicity.  Also, see if you can find a method that has been validated (and independently cross-validated) against a multiple component reference method.  Heyward and Wagner (2004) provide a good explanation of the issues assessing body comp of children as well as validation/cross-validation statistics.  That may help guide your search.  Whatever it is you select, stick with it if yours is a longitudinal evaluation of these individuals.

Have you looked at the Omron?  That handheld analyzer has been validated in children as young as 10.