SERUM SODIUM, CALCIUM AND MAGNESIUM LEVELS IN NEONATES WITH CONVULSION IN AHMADU BELLO UNIVERSITY TEACHING HOSPITAL, ZARIA, NIGERIA
Abstract
Abnormalities of biochemical elements including those of sodium, calcium and magnesium are known causes of convulsions in neonates with attendant sequelae in the neonatal period and beyond. Early detection and prompt correction of these biochemical abnormalities in cases of neonatal convulsions have been associated with favourable neurological outcomes.1, 5 Biochemical abnormalities can occur in isolation or coexist with other disease conditions as causative factors of neonatal convulsions.2, 5 Available Nigerian studies3, 4 which revealed biochemical abnormalities (including sodium, calcium and magnesium) among aetiological factors of neonatal convulsions were carried out two decades ago. None of them was a case control study. There is also no available work on the abnormalities of serum sodium, calcium and magnesium in neonates with convulsion in ABUTH, hence, the need for the present study.
METHODS
The present study was a hospital based case control work that spanned from January to December 2009 and was aimed at determining the serum levels of sodium, calcium and magnesium in neonates with convulsion in ABUTH, Zaria. The study included 96 neonates with convulsions irrespective of diagnosis and 96 age and sex matched apparently healthy neonates as controls. There were 62 males and 34 females in each group. Venous blood samples were collected inside plain sample bottles using the drop method. Estimation of serum sodium was by flame spectrophotometry method, serum calcium by O-Cresolphthalein method and serum magnesium by Megon dye method.
RESULTS
There was a male predominance among patients with a male:female ratio of 1.8:1. The mean gestational age for patients was 39.34 weeks and 39.36 weeks for controls (p=0.408). The mean weight at time of recruitment was 3000g for patients and 3144g for controls (p=0.836). The mean serum sodium level among subjects was 140±8mmo/l with a range of 123-190mmol/l while being 139±3mmol/l with a range of 130-146mmo/l in controls. The mean serum total calcium level among subjects was 2.38±0.20mmo/l with a range of 1.67-2.70mmol/l while in controls, the mean was 2.46±0.10mmol/l with a range of 2.23-2.85mmol/l. Mean serum magnesium level was 0.68±0.15mmol/l with a range of 0.30-1.00mmol/l for subjects and a mean
of 0.74±0.15mmol/l with a range of 0.40-1.10mmo/l for controls. The mean serum sodium levels did not differ significantly (p=0.636) between cases and controls whereas the mean serum levels of total calcium and magnesium were significantly higher among controls when compared to cases (p<0.05).
The prevalence of hyponatraemia among neonates with convulsions in the present study was 3.1%, for hypernatraemia 3.1%, hypocalcaemia 1.0%, while that of hypomagnesaemia was 31.3%, irrespective of diagnosis. There was no patient with hypercalcaemia or hypermagnesaemia. None of the controls had abnormal serum sodium, calcium or magnesium levels.
The commonest type of convulsion irrespective of sodium, calcium or magnesium levels was generalised clonic (52.0%), followed by generalised tonic (26.0%) with the least being the focal tonic type of convulsion (1.0%). The coexistence of abnormal serum levels of sodium, calcium and magnesium with other disease conditions such as acute bacterial meningitis, neonatal sepsis and birth asphyxia, contributed significantly to the occurrence of neonatal convulsions (p=0.01, p<0.002 and p=0.003 respectively). Out of the 96 patients studied, 22 (22.9%) died and 7 (31.8%) of them had abnormal serum levels of sodium, calcium or magnesium.
The present study has shown that mean serum calcium and magnesium levels were significantly higher in normal babies compared with those who had convulsions. Also hypomagnesaemia occurred in 31.3%, hyponatraemia in 3.1%, hypernatraemia in 3.1% and hypocalcaemia in 1% of babies with neonatal convulsions. Therefore in line with the findings of this study, it is recommended that estimation of serum sodium, calcium and magnesium be done routinely for all neonates with convulsion in ABUTH and prompt treatment of abnormalities be instituted following well established protocol. Also, multicentre or community studies should be carried out in future in Kaduna State and across the nation to establish normal reference values of these elements in Nigerian neonates.
