The different parameters of the first DXA (patients and controls) are shown in Table II. A significant statistical difference was present in the femoral neck bone mineral density (FN-BMD), FN Z-score, and lumbar spine (L2-L4) Z-score, where the patients were significantly lower than the controls. The other parameters were also lower than controls but not statistically significant. The comparison between the first and follow-up evaluation of growth and phe level is presented in Table III, showing a significant catch up of growth between the two readings except HAZ, in which improvement did not reach statistical significance. No significant statistical difference regarding the blood phe level was found. Bone mineral density in patients with phenylketonuria The baseline and follow-up DXA are compared in Table IV, showing a significant statistical increase in all parameters except the lumbar Z-score, where p > 0.05. No correlation was found between growth (WAZ, HAZ) and phenylalanine (phe) levels and duration of diet compliance as well. Also no correlation was found between the blood phe level and BMD or BMC in both evaluations. The age of the patients at baseline and follow- up was positively correlated with the mean femoral and lumbar BMD, being r = 0.7, p ≤ 0.0001 and r = 0.9, p ≤ 0.0001 respectively. A significant inverse negative correlation was present between the age of the patients and the lumbar ( L2-L4) Z-score in Table I. Comparison of growth between patients and controls (first evaluation) Parameters Age [years] Weight [kg] Height [cm] HAZ WAZ BMI [kg/m2] BMI_percentile_Egypt BMI_percentile_CDC Parameters FN_BMD [gm/cm2] FN_BMC [gm] FN_Z-score BMD_L2_L4 BMC_L2_L4 Z-score_L2_L4 Type PT C PT C PT C PT C PT C PT C PT C PT C PT C PT C PT C PT C PT C PT C Type Table II. Bone mineral status (first evaluation) N 32 42 32 42 32 42 32 42 32 42 32 42 32 42 32 42 N 32 42 32 42 32 42 32 42 32 42 32 42 Mean 8.6 8.6 28.2 33.0 121.8 128.4 –0.95 –0.17 –0.3 0.61 17.8 19.0 50.4 61.5 59.2 70.6 Mean 0.6 0.7 2.0 2.5 –0.7 0.03 0.5 0.6 14.9 17.4 –0.4 0.1 SD 4.7 3.9 2.43 2.41 4.20 2.89 0.2 0.18 0.22 0.2 0.49 0.64 5.18 3.88 5.20 3.96 SD 0.03 0.02 0.18 0.17 0.12 0.08 0.03 0.02 1.65 1.29 0.12 0.11 t-Test 0.036 1.405 1.302 2.947 3.032 1.454 1.752 1.774 t-Test 3.753 1.833 5.421 1.56 1.239 2.638 Value of p < 0.005 < 0.005 NS NS NS NS NS NS Value of p < 0.0001 NS < 0.0001 NS NS 0.01 Arch Med Sci 3, June / 2011 495