Electrolyte imbalance

Includes:
Sodium
Potassium
Calcium

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

  1. 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

  2. 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:

    Management

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


    Dependent on cause
    1. if no hypovolemia: restriction on salt and water (and diuretics)
    2. 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

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

    Potassium

    Hyperkalemia

    (potassium > 5,5 mmol/l)

    Causes

    Clinical signs

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

    Management (Depends on availability)

    Hypokalemia

    (Potassium < 3 mmol/l)

    Causes

    Clinical signs

    Management

    if > 2 mmol/L, able to feed and not having severe ongoing losses
    1. oral Potassium 1-4 mmol/mmol/kg/d
    2. Bananas, nuts, oranges

    if < 2 mmol/L or symptomatic

    emergency: arrythmias

    Cave supplementation can lead to hyperkalemia

  • treat underlying cause
  • Calcium

    ACUTE symptomatic Hypocalcemia

    CAVE common cause of neonatal seizures

    Causes

    Clinic

    Management