Effect of impaired ambulation and anti-epileptic drug intake on vitamin D status of children with cerebral palsy.

BACKGROUND: Children with cerebral palsy (CP) are vulnerable to developing vitamin D deficiency. There is little information on the prevalence and severity of vitamin D deficiency in these patients.

OBJECTIVE: To study vitamin D status in children with CP with special reference to their intake of anti-epileptic drugs (AED) and ambulatory status.

METHODS: The relative effects of AED use and ambulatory status on the vitamin D status of 120 children with CP aged 2-10 years were examined in this observational study. The patients were classified into four groups (30 in each) on the basis of AED use and ambulatory status: ambulatory (CPA), ambulatory receiving AED (CPAD), non-ambulatory (CPNA) and non-ambulatory receiving AED (CPNAD). A control group of 30 age-matched healthy children was also included. Parameters assessed included dietary calcium intake, sun exposure, serum total and ionised calcium (tCa, iCa), inorganic phosphate (iP), alkaline phosphatase (ALP), parathormone (PTH), 25 hydroxy vitamin D [25(OH)D] levels and a wrist radiograph to detect rickets. Vitamin D status was defined on the basis of serum 25(OH)D levels as normal (>50 nmol/L), mild deficiency (25-50 nmol/L), moderate deficiency (12.5-25 nmol/L), severe deficiency (<12.5 nmol/L).

RESULTS: Median (IQR) serum 25 (OH)D levels in patients with CP were 35.6 (26.75-64) nmol/L compared with 60 (37-69.25) nmol/L in controls (p = 0.04). Sixty per cent of children with CP and 36.7% of controls were vitamin D-deficient [25(OH)D < 50 nmol/L]. Children with CP had a significantly lower dietary calcium intake and sun exposure than controls (p < 0.0001 each). Serum tCa and iCa levels were significantly lower (p = 0.01 and p < 0.001, respectively) and PTH and ALP levels significantly higher (p = 0.04 and p = 0.001, respectively) in children with CP than in controls. Patients in the CPNAD group were the worst affected, 83.3% of them being vitamin D-deficient with median (IQR) 25(OH)D levels of 33.5 (12.5-45.25) nmol/L. Also, 53.3% of them had raised ALP and 17.2% raised PTH levels.

CONCLUSION: Children with CP are highly vulnerable to vitamin D deficiency. In these patients, AED use and lack of sun exposure contribute towards poor vitamin D status, the effect being more pronounced when they co-exist.