Vitamin D deficiency and rickets in children and adolescents with ichthyosiform erythroderma in type IV and V skin.

BACKGROUND: Ichthyosiform erythroderma due to keratinizing disorders may suppress cutaneous vitamin D synthesis, leading to vitamin D deficiency and rickets.
OBJECTIVES: To determine the prevalence of vitamin D deficiency and rickets in children and adolescents with congenital ichthyosis and other keratinizing disorders with erythroderma and scaling. PATIENTS AND METHODS: In this cross-sectional study, 45 children and adolescents with ichthyosiform erythroderma due to keratinizing disorders, and 66 controls (group 1: age and sex matched, with skin diseases other than keratinizing disorders; group 2: age and sex matched, healthy volunteers) were included. Evidence of rickets was determined clinically (physical examination and radiographs) and biochemically {serum calcium, phosphorus, alkaline phosphatase, 25-hydroxy vitamin D [25(OH)D] and parathyroid hormone (PTH)}.
RESULTS: All patients in the disease group had clinical, radiological or biochemical evidence of rickets [25(OH)D<20ngmL(-1) ], and analysis was done for all subjects with the available biochemical reports. The mean serum 25(OH)D levels of the disease group was 8·38±5·23ngmL(-1) and was significantly lower than in control group 1 (11·1±5·8ngmL(-1) ) (P<0·01) and control group 2 (13·5±6·9ngmL(-1) ) (P<0·001). The prevalence of vitamin D deficiency [25(OH)D<20ngmL(-1) ] was significantly higher in the disease group (n=38 of 39, 97·4%) than in control group 2 (n=12, 70·6%) (P<0·01), and total controls (n=56, 84·8%) (P=0·04). The frequency of hyperparathyroidism (PTH>65pgmL(-1) ) was also significantly higher in the disease group than in controls (P<0·01).
CONCLUSIONS: Children and adolescents with various forms of ichthyosiform erythroderma, especially those with pigmented skin (types IV-VI), are at increased risk of developing vitamin D deficiency and clinical rickets.