What is the treatment approach for hyponatremia associated with an adrenal mass?

Treatment of Hyponatremia with Adrenal Mass

The immediate priority is to determine if the adrenal mass is causing adrenal insufficiency, as this fundamentally changes hyponatremia management—glucocorticoid replacement will correct the hyponatremia and is life-saving, whereas standard hyponatremia treatments (fluid restriction, hypertonic saline) will fail if adrenal insufficiency is the underlying cause. 1, 2, 3, 4

Immediate Diagnostic Evaluation

Assess for primary adrenal insufficiency (PAI) before treating hyponatremia, as treatment must never be delayed by diagnostic procedures if acute adrenal crisis is suspected 1:

• Draw blood immediately for paired serum cortisol and plasma ACTH, serum sodium, potassium, creatinine, and glucose 1
• Hyponatremia is present in 90% of newly diagnosed PAI cases, making this a critical diagnostic consideration with an adrenal mass 1
• Serum cortisol <250 nmol/L with increased ACTH in acute illness is diagnostic of PAI; cortisol <400 nmol/L with increased ACTH raises strong suspicion 1
• Normal basal cortisol does NOT exclude adrenal insufficiency in hyponatremic patients—the level may be inappropriately low for the stress state 1, 3, 4

Critical Laboratory Patterns in PAI with Hyponatremia

• Hyponatremia is caused by sodium loss in urine plus impaired free water clearance from elevated vasopressin and angiotensin II 1
• Hyperkalaemia occurs in only ~50% of PAI cases at diagnosis 1
• Plasma renin activity is increased while aldosterone and DHEAS are low 1
• The combination may mimic SIADH, but the presence of an adrenal mass should immediately raise suspicion for PAI 2, 3, 4

Emergency Treatment Algorithm

If Acute Adrenal Crisis is Suspected (severe symptoms, hypotension, shock)

Do not delay treatment for diagnostic confirmation 1:

1. Administer hydrocortisone 100 mg IV bolus immediately to saturate mineralocorticoid receptors 1
2. Infuse 1 L of 0.9% saline over 1 hour, then continue at slower rate for 24-48 hours 1
3. Continue hydrocortisone 100-300 mg/day as continuous infusion or 6-hourly boluses 1
4. Taper parenteral glucocorticoids over 1-3 days to oral replacement once stable 1
5. Restart fludrocortisone when hydrocortisone dose falls to <50 mg/day 1

If Hyponatremia Without Crisis Features

The treatment approach depends on confirming or excluding adrenal insufficiency:

• If PAI is confirmed: Hydrocortisone replacement normalizes serum sodium without additional hyponatremia-specific treatment 2, 3, 4
• If PAI is excluded: Treat hyponatremia based on volume status and severity following standard protocols 5

Hyponatremia Correction Principles (When PAI is Excluded)

Maximum correction must not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 5:

• For severe symptomatic hyponatremia: Correct 6 mmol/L over first 6 hours or until symptoms resolve 5
• For chronic hyponatremia: Aim for 4-8 mmol/L per day 5
• Patients with advanced liver disease, alcoholism, or malnutrition require even slower correction (4-6 mmol/L per day) 5

Treatment Based on Volume Status (If PAI Excluded)

Hypovolemic hyponatremia: Discontinue diuretics and administer isotonic saline for volume repletion 5

Euvolemic hyponatremia (SIADH): Fluid restriction to 1 L/day; add oral sodium chloride 100 mEq three times daily if no response 5

Hypervolemic hyponatremia: Fluid restriction to 1-1.5 L/day for sodium <125 mmol/L; consider albumin infusion in cirrhotic patients 5

Adrenal Mass Evaluation

All patients with adrenal incidentalomas should be screened for autonomous cortisol secretion using 1 mg dexamethasone suppression testing 1:

• Screen for primary aldosteronism if hypertension or hypokalaemia present 1
• Screen for pheochromocytoma if mass >10 HU on non-contrast CT or signs of catecholamine excess 1
• Multidisciplinary review by endocrinologists, surgeons, and radiologists is indicated when imaging suggests non-benign features or hormone hypersecretion 1

Common Pitfalls to Avoid

• Never assume SIADH without excluding adrenal insufficiency when an adrenal mass is present 2, 3, 4
• Basal cortisol levels may appear "normal" but be inadequate for the stress state in hypopituitarism or PAI 3, 4
• Recurrent hyponatremia should prompt re-evaluation for undiagnosed hypopituitarism or PAI 4
• Overly rapid correction (>8 mmol/L in 24 hours) risks osmotic demyelination syndrome 5
• Treatment of suspected acute adrenal insufficiency should never be delayed by diagnostic procedures 1