Hypernatremia

Serum Na >150mEq/L

Types of hypernatremia

Low total body sodium – hypernatremic dehydration

Normal Total Body Na – central and nephrogenic DI

DI Criteria: think tons of pee

1) High serum NA (>145)

2) Polyuria (>5 ml/kg/hr). SG <1.010

3) Urine osm<<<serum osm (serum osm >290)

Correction:

1) NS bolus if dry, free water

2) Vasopressin (drip 0.5 mU/kg/hr, dbl q 30 min to max 10 mU/kg/hr)

3) DDAVP 0.4 mcg/kg IM or Sub Cut

Increased Total body Na - Primary hyperaldosteronism, Cushing’s syndrome, salt
poisoning

Diagnosis:

Obtain urine osmolality and urine sodium to obtain diagnosis

Management:

• Avoid rapid correction can cause cerebral edema
• Treat immediately symptomatic hypovolemia ie – poor peripheral pulses, delayed capillary refill, orthostatic changes with 20 ml/kg NS
  • Low total body sodium- Normal saline boluses until perfusion restores, then replace deficit over next 48hr . Goal is to drop the sodium by 0.5 to 1.0 mEq/l/hr.
    Must do hourly measurements
  • Normal Total Body Na- Maintenance fluids along with D5W one half the excess urine output and treat DI with vasopressin. Consult endocrine.
  • Increased Total body Na- Dialysis if >200 mEq/L or seizures, comatose.Otherwise give normal saline at maintenance with lasix 1mg/kg IV to achive net loss of Na
• Lower the serum sodium concentration by about 0.5 mEq/L per hour and to replace no more than half the water deficit in the first 24 hours.
• Free water deficit = body weight(kg) x percentage of total body water (TBW) x [(serum Na/140) – 1]
• ex. A serum sodium level of 155 in a 60 kg young men represents a fluid deficit of

  60 X 0.6 X ([155/140 ] – 1) or 3.9 L

• This should be replaced over 48hr