Hyponatraemia common in epileptics, tied to low bone mineral density
A low sodium concentration in the blood is commonly observed in patients with epilepsy, with moderate and severe hyponatraemia associated with reduced bone mineral density in the lumbar spine, a study has found.
The study included 695 patients with epilepsy (median age, 49 years; 53.8 percent female) who underwent a dual energy x-ray absorptiometry scan. Plasma sodium (p-Na) was measured prior to or a maximum of 14 days after the scan.
Of the patients, 72 (10.4 percent) had hyponatraemia, defined as p-Na ≤135 mmol/L. This group of patients weighed less, were older at the time of the scan, had significantly more frequent focal epilepsy, more frequently used ≥2 antiepileptic drugs (AEDs) and were also more frequently treated with enzyme-inducing AEDs compared with the group of those with p-Na >135 mmol/L.
Furthermore, hyponatraemic patients showed significantly lower T-scores in the lumbar spine, femoral neck and total femur (p<0.023). Those with moderately and severely low sodium concentration (p-Na <129 mmol/L) in the blood had even lower T-scores in the lumbar spine (p=0.030).
Hyponatraemia contributed to a significantly increased risk of osteoporosis (odds ratio, 2.91; 95 percent CI, 1.61–5.27; p=0.001).
Patients with epilepsy frequently develop hyponatraemia due to treatment with AEDs and are at increased risk of developing metabolic bone disease, researchers said. The present data highlight the need to further examine those with low sodium concentration in the blood for bone loss and osteoporosis.