The duration of illness from definitive diagnosis of IBD ranged from 0 to 48 months, while the duration from the first complaint till inclusion in the study ranged from 6 to 60 months.
Patients of the UC group were significantly older than the CD group (12.77 +/−1.71 and 10.49 +/− 3.34 years respectively). Both were comparable to the control group (11.86 +/−3.39 years; p value 0.228 and 0.202 respectively). The male to female ratio was 18:2 in the CD group, and 14:13 in the UC group (p = 0.006).
Bleeding per rectum and joint involvement (arthralgia or arthritis) were more frequently encountered among patients with UC (100%, 48.15% and 48.15% respectively) than CD (35%, 10% and 15% respectively). One of the included patients had pathological fractures of the last 3 lumbar spines.
The mean values of Z score of height-for-age was significantly lower in children with disease activity compared to controls (p < 0.001). Both groups showed a non-significant improvement after remission which remain significantly lower than controls (p < 0.001).
BMI was significantly lower in UC and CD patients during flare (17.26 +/− 2.34 and 17.13 +/− 2.46 respectively) and remission (19.27 +/− 2.07 and 20.27 +/− 3.18 respectively) than in the control group (25.43 +/−2.65) (p < 0.001). The difference between flare and remission was significant for both UC (p = 0.002) and CD (p = 0.001).
Bone mineral density and Z score of corrected BMD to bone age and sex were both significantly lower during disease activity compared to values at remission (Table ). Severe affection (Z score < −2.5) was present in 88.9% and 75% of patients with active UC and CD respectively. After remission, this decreased to 37% and 10% of patients with UC and CD, respectively (Table ). The rate of change of Z score of corrected BMD to bone age showed no significant difference between the UC and CD groups (Table ).
Comparisons of biochemical laboratory bone markers among patients and controls
Frequency of osteopenia and osteoporosis in flare and remission of UC and CD patients
Comparison of rate of changes of Z score of BMD between remission and flare among patients with UC and CD
Serum calcium was significantly lower in UC and CD patients during both disease activity (9.45 +/− 0.45 and 9.26 +/− 0.34 mg/dl respectively) and after disease remission (9.55 +/− 0.43 and 9.500 +/− 0.67 mg/dl respectively) compared to the control group (9.78 +/− 0.26 mg/dl) (p < 0.001). Although mean serum calcium increased after remission, it was not statistically different from that during remission (p > 0.05 in both groups).
Serum phosphorus was significantly lower during disease activity in UC and CD patients (3.40 +/− 1.14 and 3.57 +/− 0.93 mg/dl respectively) compared to remission values (5.16 +/− 0.54 and 5.10 +/− 0.48 mg/dl respectively) and the control group (5.22 +/− 0.48 mg/dl) (p < 0.001). Values during remission were not different from those of controls (p > 0.05).
Serum alkaline phosphatase was significantly higher in UC and CD patients during flare compared to values during remission and controls with p values of <0.0001 for all. However, remission values of both groups were not different from control group.
Similarly, urinary phosphorus was significantly higher during flare in both UC and CD patients (2.01 +/− 0.77 and 2.06+/− 0.69 g/24 hours urinary output respectively) compared to remission (0.66 +/− 0.26 and 0.61+/− 0.18 g/24 hours urinary output respectively) and controls (0.74 +/− 0.19 g/24 hours urinary output) (p < 0.001). Values during disease remission were not different from control ones.
Serum creatinine was not different between cases (flare or remission) and controls.
The 25 hydroxy vitamin D3 values were significantly lower during disease flare compared to control values. Remission values were not significantly different from values during disease activity, or from control values (Table ). On the other hand, 1, 25 (OH)2 vitamin D3 values were significantly higher during flare of UC and CD compared to controls (Table ).
FGF23 serum levels were significantly higher during disease flare in UC and CD patients compared to controls. Although values significantly decreased during remission, they remained higher than controls (Table ).
Serum parathyroid hormone was significantly higher in UC flare and remission as well as CD flare and remission than controls. Flare of UC showed significant higher values than their remission values (p = 0.019). Flare and remission values in CD were not different. Comparison of UC versus CD showed no significant differences.
Regression analysis in the ulcerative colitis group during flare showed the only significant determining factors were FGF23 followed by serum calcium. Regression analysis of BMD in CD group during flare (adjusted R2 = 0.971) showed many significant determining factors affecting BMD. On top comes 1, 21 (OH)2 VD, followed by urinary phosphorus and FGF23 (P <0.0001 for all).
Although the number of CD patients treated with infliximab is very small; the analysis of their BMD and FGF23 showed interesting results. Z score for BMD showed dramatic improvement to normal values in the 6 patients (0.89 +/− 0.67) compared to their flare (−3.32 +/− 2.31) with p value <0.0001. They showed simultaneous decrease of FGF23 to completely normal values in remission (15.38 +/− (3.11)) compared to flare (69.23 +/− (19.34)) with a p value <0.0001.