Metabolic Emergencies

Hypercalcaemia of malignancy

Syndrome of inappropriate antidiuretic hormone (SIADH)

Tumour lysis syndrome

HYPERCALCAEMIA OF MALIGNANCY

See Hypercalcaemia, including primary hyperparathyroidism.

SYNDROME OF INAPPROPRIATE ANTIDIURETIC HORMONE (SIADH)

E22.2

DESCRIPTION

• Patients present with: anorexia, nausea, vomiting, constipation, muscle weakness, myalgia, polyuria, polydipsia, neurologic symptoms (e.g. seizures, coma).
• For management, see Hyponatraemia.

REFERRAL

• Refer to Oncology Unit for management of underlying malignancy producing Antidiuretic Hormone (ADH)

TUMOUR LYSIS SYNDROME

E88.3

DESCRIPTION

• Rapid destruction of malignant cells can result in the release of cellular breakdown products and intracellular ions, causing potentially lethal metabolic derangements including acute renal failure.
• Commonly seen in cancers with rapidly growing tumours and high tumour burdens, particularly acute leukaemias, chronic myeloid leukaemia and high-grade lymphoma, generally following chemotherapy.

Presentation: (Cairo-Bishop definition)

• azotaemia
• acidosis
• hyperphosphataemia >1.45 mmol/L
• hyperkalaemia >6.0 mmol/L
• hypocalcaemia <1.75 mmol/L
• uric acid >0.476 mmol/L

GENERAL MEASURES

• There is an increased risk of arrhythmias.
• Monitor urine output.
• Monitor urine and electrolytes, creatinine and uric acid levels.

MEDICINE TREATMENT

Fluid resuscitation:

• IV hydration 2-3 L/m²/day. The urine output needs to be monitored and maintained within 80-100 mL/m²/hour.
• Diuretics are not indicated in patients with normal renal and cardiac function; and are contraindicated in patients with hypovolemia.
• Sodium chloride 0.9%, IV, 1000 mL 6-8 hourly.
  - If patient is hypernatraemic or fluid overloaded, consult a specialist.

LoE:III¹

For control of uric acid:

• Allopurinol, oral, 100 mg 8 hourly.
  - Maximum dose: 300 mg 8 hourly.
  - Adjust dose to 50 mg 8 hourly, if eGFR <20 mL/minute.

LoE:III²

Correct electrolyte imbalances:

• For hyperkalaemia, see Hyperkalaemia.
• For hypocalcaemia, see Hypocalcaemia.

REFERRAL

• Transfer to oncology unit.

Standard Treatment Guidelines and Essential Medicines List for South Africa, Hospital Level, Adults 2019 Edition