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Endocrine & Metabolic System

Fluid & Electrolyte Imbalances (Overview)

Disturbances in the body's total water volume, electrolyte concentration (e.g., Sodium, Potassium), or distribution between fluid compartments. Common in various illnesses and require careful assessment and management.

Also known as: Dehydration, Fluid Overload, Electrolyte Disturbance

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Referral and warning signs

When to refer

Refer to hospital (H/RR) / Specialist for: Severe electrolyte disturbances (esp. Na <125, K <3.0 or >6.0), Symptomatic imbalances (seizures, arrhythmias, severe weakness), Acute kidney injury, Severe acidosis/alkalosis, Need for IV fluid resuscitation or intensive monitoring, Diagnostic uncertainty regarding cause.

Red flags

  • Altered mental status, seizures, coma
  • Signs of severe dehydration or shock
  • Signs of severe fluid overload / Pulmonary oedema
  • Significant ECG changes suggestive of electrolyte imbalance (esp. K+)
  • Severe electrolyte values (e.g., Na <120 or >155, K <2.5 or >6.5)
  • Anuria / Oliguria

Signs and symptoms

  • Volume Depletion (Dehydration / Hypovolemia): Thirst, dry mucous membranes, decreased skin turgor, sunken eyes, tachycardia, postural hypotension, dizziness, reduced urine output, lethargy, confusion, shock (severe).
  • Volume Overload (Hypervolemia): Peripheral oedema, pulmonary oedema (dyspnoea, crackles), raised JVP, hypertension, weight gain, ascites.
  • Hyponatremia (Low Sodium): Nausea, malaise, headache, lethargy, confusion, seizures, coma (severity depends on level and rapidity of onset).
  • Hypernatremia (High Sodium): Thirst, dry mucous membranes, altered mental status (lethargy, irritability, weakness), seizures, coma.
  • Hypokalaemia (Low Potassium): Muscle weakness, fatigue, cramps, constipation, ileus, palpitations, ECG changes (U waves, flat T waves), arrhythmias.
  • Hyperkalaemia (High Potassium): Muscle weakness, paralysis, palpitations, ECG changes (peaked T waves, wide QRS, sine wave pattern), cardiac arrest.
  • Acid-Base Disturbances (Acidosis/Alkalosis): Symptoms often related to underlying cause and compensatory mechanisms (e.g., Kussmaul breathing in metabolic acidosis, altered mental status).

Risk factors

  • Volume Depletion: Vomiting, diarrhoea, haemorrhage, excessive sweating, inadequate fluid intake, diuretic use, burns, third-spacing (sepsis, pancreatitis, obstruction).
  • Volume Overload: Heart failure, Liver cirrhosis, Kidney failure (AKI/CKD), Nephrotic syndrome, Excessive IV fluid administration.
  • Hyponatremia: Excessive water intake (psychogenic polydipsia), SIADH (Syndrome of Inappropriate ADH), Diuretic use (thiazides), Adrenal insufficiency, Hypothyroidism, Severe HF/Cirrhosis/Renal failure (dilutional), MDMA use.
  • Hypernatremia: Inadequate water intake (impaired thirst, inability to access water), Excessive water loss (diabetes insipidus, osmotic diuresis - hyperglycemia, fever, burns), Excessive sodium intake (rare).
  • Hypokalaemia: Diarrhoea, vomiting, Diuretic use (loop/thiazide), Hyperaldosteronism, Cushing's syndrome, Certain medications (insulin, beta-agonists), inadequate intake.
  • Hyperkalaemia: Kidney failure (AKI/CKD), Medications (ACEi/ARBs, Spironolactone, NSAIDs, Potassium supplements), Adrenal insufficiency, Rhabdomyolysis, Tumour lysis syndrome, Massive tissue injury, Metabolic acidosis.

Diagnosis

Clinical assessment

Assess volume status (hydration, JVP, oedema, postural BP). Assess neurological status. Identify potential underlying causes based on history and examination.

Investigations

  • Serum Electrolytes (Sodium, Potassium, Chloride, Bicarbonate): Essential for diagnosis.
  • Urea and Creatinine: Assess renal function.
  • Blood Glucose.
  • Serum Osmolality & Urine Osmolality/Electrolytes: Help differentiate causes of sodium/water imbalance (specialist interpretation).
  • Arterial or Venous Blood Gas (ABG/VBG): Assess acid-base status (pH, HCO3, PCO2).
  • ECG: Crucial if potassium abnormalities suspected (esp. hyperkalaemia).
  • Further tests based on suspected underlying cause (e.g., cortisol for Addison's, TFTs for thyroid).

Diagnostic criteria

Diagnosis based on abnormal laboratory values for electrolytes, osmolality, or acid-base status, interpreted in clinical context.

Management

Non-pharmacological management

  • Treat the Underlying Cause.
  • Fluid Management:
  • - Volume Depletion: Oral Rehydration Solution (ORS) if mild/moderate and able to drink. IV fluids (Normal Saline 0.9% or Ringer's Lactate) for severe dehydration/shock. Rate depends on severity.
  • - Volume Overload: Fluid restriction, Sodium restriction.
  • Dietary modification (e.g., potassium restriction for hyperkalaemia).

Pharmacological treatment

  • Correct electrolyte imbalances carefully:
  • - Hyponatremia: Treatment depends on severity, duration, volume status, symptoms. May involve fluid restriction (if hypervolemic), Normal Saline (if hypovolemic), Hypertonic Saline (3% NaCl) ONLY for severe symptomatic hyponatremia in ICU setting with slow correction rate to avoid osmotic demyelination.
  • - Hypernatremia: Correct water deficit slowly, primarily with oral water or IV Dextrose 5% (D5W) or 0.45% NaCl. Avoid rapid correction (risk of cerebral oedema). Treat underlying cause (e.g., Desmopressin for central DI).
  • - Hypokalaemia: Oral potassium supplements (KCl) preferred if mild/moderate. IV KCl if severe (<2.5-3.0 mmol/L) or unable to take oral. Infuse SLOWLY via peripheral or central line (max rate ~10-20 mmol/hr), with ECG monitoring if rapid/high dose. Correct magnesium deficiency if present.
  • - Hyperkalaemia: Emergency if severe (>6.0-6.5) or ECG changes. 1) Stabilize membrane (IV Calcium Gluconate). 2) Shift K+ into cells (IV Insulin + Glucose, Nebulized Salbutamol, IV Sodium Bicarbonate if acidosis). 3) Remove K+ from body (Loop diuretics - Furosemide, Potassium-binding resins - Calcium Resonium, Dialysis). Stop offending drugs.
  • Manage Acid-Base Disorders: Treat underlying cause. Sodium Bicarbonate IV for severe metabolic acidosis (pH <7.1-7.2) - specialist guidance.
  • Diuretics (Furosemide) for fluid overload.

Monitoring

Frequent monitoring of clinical status, vital signs, fluid balance (I/O chart), weight. Frequent monitoring of electrolytes (esp. Na, K) and renal function during correction. ECG monitoring if significant potassium abnormalities.

Complications

  • Related to specific imbalance (e.g., Cardiac arrhythmias from K+ disorders, Seizures/coma from Na+ disorders, Cerebral oedema/osmotic demyelination from rapid correction).
  • Complications of underlying disease.
  • Complications of treatment (e.g., fluid overload).

Prevention

  • Adequate fluid intake, especially during illness/hot weather.
  • Appropriate management of underlying diseases (HF, CKD, Diabetes).
  • Judicious use of diuretics and other medications affecting electrolytes/fluids.
  • Monitoring electrolytes in patients at risk.

Patient education

  • Explanation of the imbalance and its cause.
  • Importance of fluid/dietary recommendations.
  • Medication adherence if prescribed.
  • Symptoms requiring urgent attention.
  • Importance of follow-up monitoring.

Uganda-specific notes

Dehydration from diarrhoeal illness is a major cause of fluid/electrolyte imbalance, especially in children (ORS is critical). Hyperkalaemia in CKD/AKI difficult to manage due to limited dialysis access. Careful IV fluid management crucial.

References

  • Uganda Clinical Guidelines (UCG) 2023

    Chapter 1, Section 1.1.4

For learning and professional reference. Use current local guidance and clinical judgement.

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