. 2023 Aug 2;30(8):7315–7334. doi: 10.3390/curroncol30080531

Table 2.

Presentation and management of metabolic emergencies.

Syndrome	Presentation	Management
Syndrome of inappropriate antidiuretic hormone (SIADH)	❖ Urine osmolarity > 100 mOsm (coincident with euvolemic hypotonic hyponatremia) ❖ Corresponding serum Na levels: - Mild: 130–134 mEq/dL - Moderate: 125–129 mEq/dL - Severe: <125 mEq/dL ❖ Acute hyponatremia with headaches or neurocognitive slowing. ❖ Severe hyponatremia can be associated with seizures or death. REMEMBER: ❖ Must be distinguished from hypovolemic hyponatremia (urine osmolarity > 300 mOsm; urine sodium < 20 mEq/L). Main cause: excessive gastrointestinal loss.	❖ Symptomatic hyponatremia: 100 mL 3% normal saline bolus to acutely raise serum sodium by 2–3 mEq/L. ❖ Chronic hyponatremia: Free water restriction and sodium chloride tablets. REMEMBER: ❖ Total increase in serum sodium by no more than 4–6 mEq/L in 24 h to avoid central pontine myelinolysis. ❖ Correction of hyponatremia is usually necessary prior to initiating systemic therapy.
Hypercalcemia	❖ Corresponding serum Ca levels: - Mild: 10.5–11.9 mg/dL - Moderate: 12.0–13.9 mg/dL - Severe: ≥14.0 mg/dL ❖ In the case of hypoalbuminemia, observed serum calcium must be further increased by 0.8 * (4.0—serum albumin) mg/dL. ❖ Presentation: altered mental status, muscle weakness, constipation, dehydration with ensuing acute kidney injury, urolithiasis (in subacute presentations).	❖ Immediate aggressive intravenous hydration with normal saline (1–2 L in the first hour, followed by 2 L at 200 mL/hr with close monitoring of volume status). ❖ Early intravenous bisphosphonate administration (most commonly zolendronic acid). ❖ Supplemental calcitonin can be administered during the first 48 h while the bisphosphonate is not yet at peak efficacy. Denosumab is alternatively administered in bisphosphonate-refractory cases. ❖ Loop diuretics are generally now avoided as they can exacerbate hypercalcemia and kidney injury in inadequately hydrated patients.

Syndrome

Presentation

Management

Syndrome of inappropriate antidiuretic hormone (SIADH)

❖
Urine osmolarity > 100 mOsm (coincident with euvolemic hypotonic hyponatremia)
❖
Corresponding serum Na levels:
- -
  Mild: 130–134 mEq/dL
- -
  Moderate: 125–129 mEq/dL
- -
  Severe: <125 mEq/dL
❖
Acute hyponatremia with headaches or neurocognitive slowing.
❖
Severe hyponatremia can be associated with seizures or death.

REMEMBER:

❖
Must be distinguished from hypovolemic hyponatremia (urine osmolarity > 300 mOsm; urine sodium < 20 mEq/L). Main cause: excessive gastrointestinal loss.

❖
Symptomatic hyponatremia: 100 mL 3% normal saline bolus to acutely raise serum sodium by 2–3 mEq/L.
❖
Chronic hyponatremia: Free water restriction and sodium chloride tablets.

REMEMBER:

❖
Total increase in serum sodium by no more than 4–6 mEq/L in 24 h to avoid central pontine myelinolysis.
❖
Correction of hyponatremia is usually necessary prior to initiating systemic therapy.

Hypercalcemia

❖
Corresponding serum Ca levels:
- -
  Mild: 10.5–11.9 mg/dL
- -
  Moderate: 12.0–13.9 mg/dL
- -
  Severe: ≥14.0 mg/dL
❖
In the case of hypoalbuminemia, observed serum calcium must be further increased by 0.8 * (4.0—serum albumin) mg/dL.
❖
Presentation: altered mental status, muscle weakness, constipation, dehydration with ensuing acute kidney injury, urolithiasis (in subacute presentations).

❖
Immediate aggressive intravenous hydration with normal saline (1–2 L in the first hour, followed by 2 L at 200 mL/hr with close monitoring of volume status).
❖
Early intravenous bisphosphonate administration (most commonly zolendronic acid).
❖
Supplemental calcitonin can be administered during the first 48 h while the bisphosphonate is not yet at peak efficacy.

Denosumab is alternatively administered in bisphosphonate-refractory cases.

❖
Loop diuretics are generally now avoided as they can exacerbate hypercalcemia and kidney injury in inadequately hydrated patients.