Sodium correction formula

hyponatremia and hypernatremia correction formula explained with example

1. SODIUM CORRECTION FORMULA
DR. RAVIKIRAN H M
HYPONATREMIA
STEPS:
1. Change in S. Na
+
with 1lt infusate (Adrogus-Madias equation) in meq/lit
=
??????����??????�� ???????????? −����� ????????????
��??????+1

2. Volume required in lit
=
������� ����� ????????????−����� ????????????
��??????��� �� ����� �?????? ���� 1��� �����??????��

=
140−����� ????????????
��??????��� �� ����� �?????? ���� 1��� �����??????��

3. Time required in hrs
=
������� ����� ????????????−����� ????????????
�??????�� �� ����������

=
140−����� ????????????
�??????�� �� ����������

4. Run rate in ml/hr
=
������ ��������
���� ��������


Note:
FLUID Na
+
in meq/lit
3% NS 513
0.9% NS 154
RL 130
0.45% NS 77
5D 0

Total body water (TBW) =0.6xBW in men

2. =0.5xBW in women
Na
+
deficit=0.6xBWx[140-Na
+
]
H2O deficit=0.6xBWx[
????????????−140
140
]
Example:
70kg Male, Serum Na
+
110, rate of correction 1meq/hr, using 3% NS
1. Change in S Na
=
513−110
0.6�70 +1
=
403
43
=9.37���/���
2. Volume
=
140−110
9.37
=
30
9.37
=3.2���
3. Time
=
140−110
1
=30��
4. Run rate
=
3200
30
=106��/��
Thus correction is: 3%NS at 106ml/hr for 30hrs.

3. HYPERNATREMIA


Example:
70kg male, serum Na 160, rate of correction 0.5meq/hr, using 5D
First method:
Change in Serum Na
=
0−160
0.6�70 +1
=
−160
43
=−3.72���/���
Volume required
=
140−160
−3.72
=
−20
−3.72
=5.37���
Time required
=
140−160
0.5
=
20
0.5
=40���
Run rate
Two methods
same steps as hyponatremia H2O deficit formula

4. =
5370
40
=134��/��
Thus rate of correction is 5D at 134ml/hr for 40hrs.

H2O deficit method
=0.6×70(
160−140
140
)=6���
So 6lit over 48hrs
=
6000
48
=125��/��