ESPE Abstracts

Introduction: Non-nutritional rickets forms are often unrecognized. A late diagnosis could negatively affect the outcome. The aimof this study is to identify peculiar clinical and biochemical signs at the onset of non-nutritional rickets to promote early diagnosis.

Materials and Methods: A retrospective monocentric observational study was conducted on a sample of outpatients consecutively evaluated at the pediatric endocrinology center from July 2016 to December 2023 for rickets. Medical history, auxological, clinical and laboratory data (calcium-phosphorus metabolism) were evaluated. Continuous variables were expressed in mean±DS, while the categorical variables in percentage. A p-value <0.05 was considered statistically significant.

Results: Three hundred and five patients were recruited (age 6.50 ±3.65 years), divided into two groups: 23 patients with hypovitaminosis D/hypocalcemic rickets (HypoVD/HypoCa group, age 7,93±4,07 years) and 12 with hypophosphatemic rickets (HypoP group, age 3,76±2,37 years). Patients in the HypoP group were significantly younger (P = 0.003). In the hypoVD/hypoCa group, 56% had vitamin-D deficiency nutritional rickets, 17.4% had rickets related to antiepileptic therapy, 21.7% related to obesity/overweight and 4% to genetic causes (1 case of vitamin-D-resistant rickets). In the hypoP group, 91.6% of patients had hypophosphatemic X-linked rickets (mean age at diagnosis 4±2,39), while in the 8.4% had iatrogenic cause (1 patient, hypophosphoremia related to chronic alginate therapy). Clinically, 39.1% of the hypoVD/hypoCa group were asymptomatic; in 34% there was varism of the lower limbs that, in the patient with genetic cause, was associated with rachitic bracelet; in one case only hypocalcemia was documented. In hypoP group, 91.7% had varism of the lower limbs, associated with rachitic bracelet (33%), macrocrania (25%), non-traumatic fractures (8.3%) or other (keeled thorax, saddle nose; 16,7%). Cognitive impairment was reported in 25% of cases. Short stature was significantly more frequent in the hypoP group (75% vs 17.4%, P = 0.000). With regard to biochemical data: in the hypoP group, ALP levels were significantly higher than in the hypoVD/Ca group (753±326.16 U/L vs 407.95 ±196.28 U/L, P = 0.002), while phosphate levels were significantly lower (2.7±0.39 vs 4.8±0.55, P = 0.000). There were no significant differences for calcemia, PTH and 25OH-vitamin D.

Conclusion: Early onset, varism of the lower limbs (especially if associated with other signs of rickets or non-traumatic fractures), hypophosphatemia, and increased ALP may be suggestive for a non-nutritional rickets. These findings should lead paediatricians to suspect the early diagnosis of non-nutritional forms of rickets.