Electrolyte imbalance

Sodium

Hypernatremia

(Sodium > 150 mmol/l)

Causes

Loss of water in excess of sodium	Inadequate water intake, renal water loss	Gain of sodium in excess of water
Diarrhea/ vomiting Burns Pyrexia	Diabetes insipidus central (stroke, meningitis, head trauma) or renal Hyperglycaemia Diuretics Renal disease	Oral ingestion/ salt poisoning Excessive IV administration/ nasogastric feeds Drugs Cushing syndrome/ Conn’s disease, CAH

Clinical signs

Lethargy, irritability, tachycardia, hypotension, dry mucous membranes, doughy feel to skin
Severe symptoms if > 160: seizures (especially in acute hypernatremia), confusion, coma

Complications

acute hypernatremia: CNS hemorrhages, mental retardation
death: especially if > 2 days duration

Management

Aim: gradual lowering of sodium level to prevent cerebral oedema, central pontine myelinosis

Hypernatremic dehydration

if > 155 need IV fluids, use Normal saline. Normal hydration should be achieved slowly over 48 hours, the sodium shouldn’t be reduced by > 0,5 mmol/h
Online fluid calculator: www.medcalc.com/sodium.html
Hypernatremia due to salt excess

Will correct spontaneously if renal function is normal
Frusemide and replacement of water

Ensure nutrition as soon as possible (no longer than 2 days on I.v. fluids only), may need NGT feeds

Hyponatremia

(Sodium < 130 mmol/l)

Causes

Hypovolemic Hyponatremia	Hypervolemic Hyponatremia	Euvolemic Hyponatremia	Pseudohyponatremia
GI loss: vomiting, diarrhea Third spacing: peritonitis, paralytic ileus, pancreatitis, burns, rhabdomyeolysis Renal loss (diuretics,tubular damage, adrenal pathology: Tb, Addison, hemorrhage) Skin loss: cystic fibrosis, CAH Cerebral salt wasting (CNS trauma, infection, bleed, tumor)	nephrotic syndrome cirrhosis congestive heart failure chronic renal failure	Hypothyreodism primary polydypsia SIADH Iatrogenic (hypotonic IV fluid)	hyperlipidemia or hyperproteinemia lab problem

Clinical signs

mild (120-130): nausea, vomiting, malaise, weakness, muscle cramps, anorexia, decreased muscle reflexes

severe (110-120): headache, lethargy, restlessness, disorientation, cranial nerve palsies

severe/ rapid developed hyponatremia can cause seizures, coma, respiratory arrest, death

also examine:

Volume status, HR, JVP, BP
check for underlying illness: CHF, cirrhosis, hypothyreoidism

Management

caution with rapid correction of severe hyponatremia associated with central pontine myelinolysis (irreversible)

Dependent on cause

if no hypovolemia: restriction on salt and water (and diuretics)
if hypovolemia: normal saline 0,9% iv, do not exceed 0,5 mmol/h.
Online fluid calculator: www.medcalc.com/sodium.html

treat underlying condition

in SIADH: fluid restriction (consider diuretics)
in cerebral salt wasting: normal saline iv

Potassium

Hyperkalemia

(potassium > 5,5 mmol/l)

Causes

Impaired excretion
1. renal failure
2. addisons disease
transcellular shift
1. metabolic/ respiratory acidosis, hyperglycemia (i.e. ketoacidosis)
2. tissue damage (rhabdomyolysis, burns, trauma)
3. tumor lysis syndrome
medication-induced
1. potassium supplements
2. NSAIDs, Cotrimozazol and others
endocrine

congenital adrenal hyperplasia/hypoplasia
primary hypoaldosteronism

Cave: pseudohyperkalemia. Related to red cell lysis during collection and transport of sample, spherozytosis, traumatic venipuncture

Clinical signs

(generally not manifest until potassium > 7 mmol/l)

Muscle weakness, bradycardia, obstipation, decreased tendon reflexes, flaccid paralysis or extremities
Cardiac arrhythmia
ECG changes: Peaked T-waves, loss of P-wave, widened QRS, ST-depression
Cardiac arrest (K >9 mmol/l)

Management (Depends on availability)

Salbutamol nebulizer 2.5-5 mg, repetitively
Discuss with senior if severe for
1. Calcium gluconate 10% 0,5ml/kg in 5 minutes
2. if plus metabolic acidosis: Sodium bicarbonate 1-2 mmol/kg iv over 30 minutes
3. Glucose 0,5 g/kg (Glucose 20% 2,5 ml/kg and insulin 0,1 units/kg as a bolus. Monitor glucose
4. Peritoneal dialysis

Hypokalemia

(Potassium < 3 mmol/l)

moderate: 2.5- 3 mmol/L
severe: < 2.5 mmol/L

Causes

decreased intake
1. malnutrition
2. prolonged IV fluid administration
Intestinal losses
1. Vomiting, diarrhea
2. malabsorption i.e. HIV enteropathy
intracellular shift of potassium
1. metabolic alkalosis
2. acute stress
3. Insulin treatment
renal loss
1. drugs: diuretics, aminoglycosides, steroids, high dose salbutamol
2. hyperaldosteronism
3. osmotic diuresis (i.e. poorly controlled diabetes)
4. glomerulonephritis, Pyelonephritis, tubulopathy

Clinical signs

apathy → coma
muscle weakness, paralysis, including respiratory muscles
GI hypomotility → constipation, paralytic ileus
cardiovascular:
1. Arrhythmia: ECG-changes - flat T-waves, ST-depression
2. hypotension
3. cardiac arrest
hyperglycemia

Management

if > 2 mmol/L, able to feed and not having severe ongoing losses

oral Potassium 1-4 mmol/mmol/kg/d
Bananas, nuts, oranges

if < 2 mmol/L or symptomatic

IV: maintenance 2 mmol/kg Potassium plus deficit (3,5 mmol- measured potassium)/kg

for example:
7 kg infant potassium 1,5 mmol/L in lab:
2x 7 + (3,5-1,4) x 7 = 28 mmol
do not exceed 0,2 mmol/kg/h

emergency: arrythmias

0,5 mmol/kg potassium in 20 mls normale saline over 30 minutes. Concentrations should not exceed 80 mmol/L.

Cave supplementation can lead to hyperkalemia

treat underlying cause

Calcium

ACUTE symptomatic Hypocalcemia

CAVE common cause of neonatal seizures

Causes

respiratory alkalosis due to hyperventilation
acute kidney disease
infection: sepsis, acute pancreatitis
rhabdomyelysis, tumor lysis syndrome, burns
congenital

Clinic

fatigue, circumoral or distal extremity paresthesiasis, neuropsychiatric symptoms muscle cramps, seizures
latent tetany: Chvostek's and Trousseau's signs

Management

normoventilation
treat underlying cause
only if severe symptoms/seizures:
Calcium gluconate 10% (940mg/ 10 ml = 2,1 mmol) 20mg/ kg (=0,2ml/ kg)
diluted 1:1 with Normale saline over 10-15 minutes
Can be given 1-2 times/day
Do not run faster than 4 ml of this solution (0,45 mmol Calcium) per minute