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Anticonvulsant-Induced Rickets

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Case: Anticonvulsant-Induced Rickets

Reported by Andrew Porter

L.D., a 14 year old male with severe mental retardation and epilepsy, was referred for consideration of scoliosis.

The curve was found to be minimal but examination showed deformity of the right wrist. Xray revealed features diagnositic of rickets. An Xray of his left wrist taken 5 years previously was normal. A history of medication with phenytoin and phenobarbitone was elicited from his care-givers. He was placed on vitamin D supplementation.

On follow up, the rachitic changes in his wrist have significantly improved.

Left wrist, 1994

Right wrist, March 1999

Right wrist, June 1999

Right wrist, October 1999


FROM: Myles Clough

As an orthopaedic surgeon, I thought that this case was extremely rare as we come across this type of problem so infrequently. However, reviewing the literature for this site suggested a very different picture. High incidences of rickets (around 4%) were reported in institutionalized epileptic children and numerous studies suggested that abnormalities of vitamin D metabolism are present throughout that population. Increased risk factors appear to include non-ambulatory status, poor diet and lack of exposure to sunlight - all presumably correlated with the severity of mental retardation. Various papers suggest that vit D supplements should be routinely offered to the population of mentally retarded, epileptic, poorly ambulant children. Osteomalacia in the older institutionalized epileptic patient is also common.

There is little in the orthopaedic literature but a study by Lee et al in Detroit shows that pathological fractures in this population are common. They suggest that vitamin D levels should be measured in all such children with fractures and that non-accidental injury should be ruled out where the vitamin D level is normal!


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Ishitsu T, et al. Anticonvulsant-induced rickets associated with renal tubular acidosis and normal level of serum 1,25-dihydroxyvitamin D. Am J Dis Child. 1981 Dec;135(12):1140-2.

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Kruse K, et al. Serum alkaline phosphatase isoenzymes in epileptic children receving anticonvulsant drugs. Eur J Pediatr. 1977 Nov 4;126(4):237-42.

Sherk HH, et al. Vitamin D prophylaxis and the lowered incidence of fractures in anticonvulsant rickets and osteomalacia. Clin Orthop. 1977 Nov-Dec;(129):251-7.

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Addy DP. Rickets associated with anticonvulsant therapy in children with tuberous sclerosis. Arch Dis Child. 1976 Dec;51(12):972-4.

Baleva R, et al. Bone metabolic disorders after prolonged treatment with antiepileptic agents in a patient with idiopathic hypoparathyroidism. Vutr Boles. 1976;15(5):93-7. Bulgarian.

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No authors listed. Anticonvulsant osteomalacia. Arch Intern Med. 1975 Jul;135(7):997-1000.

Dent CE. Rickets and osteomalacia of various origins. Birth Defects Orig Artic Ser. 1971 May;7(6):79-85.

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