ESPN 51th Annual Meeting

ESPN 2018


 
HYPOMAGNESAEMIA IN CONGENITAL NEPHROTIC SYNDROME: EVALUATION OF 12 PATIENTS
RANDULA RANAWAKA 1 MANOJI GAMAGE 2 ASHEETA GUPTA 3 DAVID MILFORD 3

1- FACULTY OF MEDICINE, UNIVERSITY OF COLOMBO
2- NUTRITION UNIT, LADY RIDGEWAY HOSPITAL FOR CHILDREN
3- BIRMINGHAM CHILDRENS HOSPITAL, UK
 
Introduction:

Infants with congenital nephrotic syndrome present at birth or within the first three months of life with heavy proteinuria, hypoalbuminaemia and oedema. Magnesium (Mg) is the fourth commonest cation within the body and is vital for many functions. Severe hypomagnesaemia can lead to seizures, arrhythmias and even sudden death.

Hypomagnesaemia is a recognised finding in children with congenital nephrotic syndrome but there are few reports of the incidence or consequences of hypomagnesaemia in these children.

 

Material and methods:

A retrospective analysis of 12 patients with congenital nephrotic syndrome presenting to paediatric nephrology referral centre, UK between January 2006 and September 2015. Plasma Mg, calcium (Ca) and albumin measured in the first week of presentation were analysed. The normal ranges for adjusted serum Ca and total serum Mg were 2.2-2.7 mmol/L and 0.7-1.0 mmol/L respectively.  Fractional excretion of Mg was measured in two patients.

 

Results:

Eight patients had serum Mg less than 0.7mmol/L. Of these 4 developed seizures (mean Mg -0.33mmol/L, range 0.22-0.42 mmol/L) and all had serum albumin level of <12g/L. Two of 4 patients who developed seizures had adjusted serum Ca less than 2.2mmol/L (1.8 and 1.9 mmol/L) and the other two patients had normal adjusted serum Ca levels. Only 4 children had genetic studies (3 nephrin mutations, one WT1 mutation).

Four patients had normal serum Mg levels. Eight patients had normal adjusted serum Ca levels. Three of 4 Patients with normal serum Mg had a serum albumin >18g/L. The fractional excretion of Mg was calculated in two patients who presented with seizures (1.07% and 0.98%, normal - <2%). 

 

Conclusions:

Hypomagnesaemia is common in congenital nephrotic syndrome. The severity of hypomagnesaemia in patients with congenital nephrotic syndrome correlates with low serum albumin levels. Hypomagnesaemia and not hypocalcaemia is an important cause of seizures in these patients.