The necessity of assessing bone health in children with chronic illness
Addressing bone health in children with chronic illness is important. Early detection of signs of bone fragility, by active screening using newer imaging techniques will help.
Antiepileptic drug therapy (AED) influences the vitamin D-PTH axis and results in altered bone mineral density. Hepatic induction of the cytochrome P450 enzyme system leads to accelerated catabolism of vitamin D into its inert metabolites. This further decreases the intestinal absorption of calcium, lowering serum calcium concentration. The parathyroid gland is then stimulated to secrete PTH. The net result is the mobilization of calcium and phosphorus from the bone causing demineralized bone, which is more susceptible to fractures.
Unfortunately, screening for mineral defects or prophylactic treatment with calcium and vitamin D is not routinely done. Early identification and intervention of bone disease during AED treatment is very important. Clinicians managing children with epilepsy should provide common bone health guidance to those on long term AEDs. This includes enhancing weight bearing, sun exposure and sufficient dietary intake of calcium and vitamin D. Children on long term AEDs are at risk of impaired bone health and should receive vitamin D supplementation at a minimum of 400 -600 IU daily based on age.
Chronic disease in childhood suppresses bone growth and leads to abnormal bone mass, geometry and microarchitecture and predispose to pathological fractures. Chronic inflammation mediated by proinflammatory cytokines and the use of supraphysiological doses of glucocorticoids is an additional factor.
A 9-and-a-half-year-old girl with primary immune deficiency was brought for evaluation of growth retardation. She had recurrent respiratory infections from early infancy including ear infections, pneumonia, protracted diarrhoea in infancy and mucocutaneous candidiasis. She had bronchiectasis secondary to recurrent pneumonia and was also intolerant to certain foods. She suffered from intermittent foul smelling, bulky stools (steatorrhea) and as a result, her mother had stopped giving her milk and milk products. She had generalised apathy and difficulty playing with her peers.
Evaluation showed severe hypocalcemia (S.Ca 6.4 mg/dl), normal phosphorus (5.4 mg/dl) and normal alkaline phosphatase(194 U/L). She had very low Vitamin D levels (9.44 nmol/L). A hand x-ray showed severe osteopenia and mild delay in bone age (7-8 years). She was started on therapeutic doses of Vitamin D and Calcium. Within a month of initiating treatment, there was remarkable improvement in her general well-being and activity. She started tolerating most food items that had been previously excluded from her diet including milk. Her steatorrhea reduced remarkably, and she started passing normal stools.
Monitoring growth and puberty in these children is essential as it is detrimental to skeletal health. Evaluating vertebral abnormalities is important and should involve screening in high-risk groups. Where there is residual growth potential and scope for bone recovery, bone protective therapies may not be necessary. If concomitant growth failure and pubertal delay co-exist, management of these may indirectly improve bone health. In conditions where there is little scope for bone recovery and in older children, bone targeted therapy may be considered at an earlier stage, although there is still a paucity of data on this subject.
This case highlights the necessity of assessing bone health in children with chronic illness. Their main morbidities eclipse co-existing issues and aggravate their suffering. In routine OPD practice, screening for these parameters will help us to improve the overall well-being of these children.