Rickets:

Not all rickets is vitamin D deficiency

Although vitamin D deficiency is a common cause of rickets, other types of rickets, including hereditary forms, must be considered in the differential diagnosis. The patient described here presented for evaluation of bowing of his lower extremities, and was ultimately diagnosed with X-linked hypophosphatemic rickets, a disorder caused by renal wasting of phosphate that occurs as a result of a mutation in the PHEX gene.

Nutritional rickets and z scores for height in the United Arab Emirates: to D or not to D?

BACKGROUND

Vitamin D deficiency is still prevalent worldwide, including the Middle East. A cohort of patients with nutritional rickets was treated with vitamin D(2) (ergocalciferol) alone. After this intervention, patients were followed to document changes in z scores for height after treatment. The secondary aim was to determine the proportion of affected children who had vitamin D deficiency or calcium deficiency.

METHODS

Z score for height was calculated as the difference between the observed value and the median value, divided by the SD of the population. Z scores were compared in patients before and after treatment.

RESULTS

The improvement in z score after treatment was 0.86 +/- 0.95. The 95% confidence interval for the mean difference was 1.32-0.40 (t = 3.95, P < 0.001). With a diagnostic cut-off for 25 hydroxyvitamin D(3) (25D) deficiency of <25 nmol/L, only half were diagnosed with severe vitamin D deficiency. The remaining patients had presumable calcium deficiency. The alkaline phosphatase (ALP) was negatively correlated to z scores, implying that higher ALP concentrations predicted severe bone disease (lower z scores). The variables 25D and age were moderately and positively correlated (Pearson's r = 0.59, 95%CI: 0.15-0.84; P = 0.01), indicating that younger infants had the lowest 25D levels.

CONCLUSION

Vitamin D alone was efficient in resolving radiological and biochemical disturbances as well as improving z scores for height in a cohort of children with nutritional rickets, which included patients with 25D deficiency as well as calcium deficiency. The results support the hypothesis of the interplay and continuum of 25D deficiency and calcium deficiency in the pathogenesis of rickets.