Parathyroid function and serum calcitonin in children receiving anticonvulsant drugs

Osteoporosis Associated with Epilepsy and the Use of Anti-Epileptics-a Review

The increased rate of fractures associated with epilepsy has been long recognised but remains incompletely understood. Study quality and study results have varied, with some but not all studies showing bone diseases including osteoporosis and/or osteomalacia, and a high prevalence of vitamin D insufficiency and deficiency are also noted. Falls risk can also be higher in patients with epilepsy taking anti-epileptic medications, potentially leading to fracture. Larger research collaborations are recommended to further advance understanding in this field, particularly to examine underlying genetic and pharmacogenomic associations of epilepsy and anti-epileptic medication usage and its association with bone diseases and fractures, as well as further investigation into optimal management of bone health in epilepsy.

Efeitos do fenobarbital sobre o reparo e a biomecânica de ossos em ratos Wi star

OBJETIVO: Avaliar os efeitos morfológicos do tratamento com fenobarbital, sobre a neoformação óssea e sobre a biomecânica óssea do osso de ratos Wistar. MÉTODOS: Foram utilizados dez ratos divididos em dois grupos: controle (CT) e fenobarbital (FE). O grupo FE recebeu doses diárias de fenobarbital 0,035 ml/kg via intramuscular, por 60 dias. O grupo CT recebeu a mesma dose e via de administração de solução fisiológica 0,9%. Após 30 dias, foi realizada uma falha óssea no osso parietal e implantada a hidroxiapatita porosa (HAP) em cavidades nas tíbias. Após as cirurgias, manteve os respectivos protocolos até completar 60 dias e serem eutanasiados, sendo os ossos coletados. RESULTADOS: O volume de osso formado ao redor HAP na falha parietal e os achados biomecânicos foram menores nos animais do grupo FE em relação ao CT. CONCLUSÃO: O uso prolongado do fenobarbital interfere no reparo ósseo após lesões, diminui a osseointegração de implantes de HAP e torna os ossos menos resistentes.

Monomeric serum calcitonin and bone turnover during anticonvulsant treatment and in congenital hypothyroidism

Decreased basal and calcium-stimulated calcitonin serum levels have been found in children with congenital hypothyroidism and in those receiving anticonvulsant drugs. The purpose of our investigation was to confirm these results using a new technique for calcitonin measurement and to study the effect on bone turnover. Calcitonin serum levels were measured with two different antibodies before and after a low-dose Ca infusion in patients receiving phenytoin, primidone, carbamazepine, or valproate and in patients with congenital hypothyroidism receiving L-thyroxine. In comparison with control values, basal and Ca-stimulated extractable calcitonin, representing the monomeric and biologically active form of the hormone, were moderately decreased in patients with epilepsy receiving phenytoin and primidone, and severely decreased in patients with hypothyroidism. Ca and bone metabolism were normal, except for an elevated renal threshold for phosphate (indicating phosphate conservation) in patients receiving phenytoin and primidone, and increased fasting urinary excretion of Ca and hydroxyproline (indicating increased bone resorption) in patients with hypothyroidism. The secretory capacity of the C cells for monomeric calcitonin is decreased in children receiving treatment with some, but not all, anticonvulsant drugs, and lacking in patients with hypothyroidism. Patients with calcitonin deficiency may be prone to osteopenia if the tendency to increased osteoclastic activity is aggravated by secondary hyperparathyroidism in patients with epilepsy receiving phenytoin and primidone or by inappropriate thyroid replacement therapy in patients with hypothyroidism.

A survey of 37 cases with basal ganglia calcification (BGC): CT-scan findings of BGC and its relationship to underlying diseases and epilepsy

Thirty-seven cases that showed bilateral basal ganglia calcification (BGC) were found in 5987 patients. These cases (0.6%) were studied in relation to their CT findings, underlying diseases and epilepsy. CT findings of BGC were divided into "localized" type (33 cases) and "diffuse" type (4 cases). The number of patients with the "localized" type clearly seemed to increase with age. The M:F ratio of the "localized" type was 1:2. The "localized" type was seen in both idiopathic BGC and familial BGC. The "diffuse" type was seen in hypoparathyroidism only. The specific relationship of these two types of BGC to underlying diseases, however, does not fully agree with results so far reported. We experienced a case with familial BGC during this study that appears to be only the 15th so far reported. Partial epilepsy occurred in 75% of epilepsy with BGC, but there seemed to be no direct relationship between BGC and epileptogenicity.

Decreased bone density in severely handicapped children and adults, with reference to the influence of limited mobility and anticonvulsant medication

Bone density and related biochemical parameters were investigated in institutionalised children and adults with severe handicaps, who were classified according to the degree of limited mobility (group 1, bed-ridden; group 2, capable of crawling; group 3, capable of walking) and according to whether or not they were receiving anticonvulsants. As determined by microdensitometric analysis of radiograms of the second metacarpal bone, bone width (D), bone pattern area (sigma GS) and bone salt density (sigma GS/D) were decreased in the patients, the decreases being most prominent in group 1, followed by groups 2 and 3, in that order. Significant decreases of sigma GS and sigma GS/D, but not of D, were found in patients on anticonvulsant treatment in comparison to patients without therapy. Serum alkaline phosphatase (Al-p) and parathyroid hormone (iPTH) as well as urinary calcium and cyclic adenosine-3',5'-monophosphate (cAMP) excretion were significantly increased in group 1. In comparison to patients without therapy, anticonvulsant-treated children showed significantly decreased levels of serum calcium (Ca), ionised Ca (Ca2+), 25-hydroxy vitamin D3 and urinary phosphate (PO4) excretion, and elevated levels of Al-p, iPTH and calcitonin (iCT). It is suggested that limited physical activity results in a mild hyperparathyroid state, which is aggravated in patients on anticonvulsant treatment.

Reduced bone growth in rats treated with anticonvulsant drugs: a type II pseudohypoparathyroidism?

The effect of anticonvulsant drugs on bone growth and calcium metabolism was studied in Wistar strain rats. Animals were treated for 40-48 days with diphenylhydantoin (DPH) or sodium valproate (SV), or were thyroparathyroidectomized (TPTX) and maintained with thyroxine supplements. Bone growth, measured radiographically as increase in bone length, was reduced by up to 12% in the drug-treated and TPTX groups. Plasma iPTH concentrations were raised twofold- to threefold by DPH and SV. Total plasma calcium was not significantly altered in the DPH-treated rats but was elevated by SV treatment. Similarly, elevated iPTH and normal calcium values were also found in carbamazepine-treated and diazepam-treated rats in a separate experiment. Plasma alkaline phosphatase was reduced by high doses of the drugs. These results imply that anticonvulsant drugs induce end-organ resistance to PTH (a feature of pseudohypoparathyroidism), which may be responsible for some of the skeletal and dental abnormalities found in patients treated with anticonvulsants.