What is the immediate management for a newborn with panhypopituitarism, presenting with low thyroid hormone, low cortisol, and low growth hormone levels?

Immediate Management of Neonatal Panhypopituitarism

Give hydrocortisone immediately—this is the critical first step that must be initiated before any other hormone replacement to prevent life-threatening adrenal crisis. 1

Priority: Glucocorticoid Replacement First

Hydrocortisone must be started immediately upon diagnosis at 8-10 mg/m²/day divided into 2-3 doses. 1 This is non-negotiable because:

• Cortisol deficiency is the primary cause of excess mortality in hypopituitarism 1, 2
• Acute adrenal crisis can be fatal if untreated 1
• Hypoglycemia in this setting requires immediate exclusion and treatment of cortisol deficiency 1, 3
• The newborn with panhypopituitarism is at immediate risk for hypotension, hypoglycemia, and hyponatremia 1

Sequential Hormone Replacement Protocol

After stabilizing with hydrocortisone, follow this specific sequence:

Step 1: Hydrocortisone (Day 1)

• Start immediately at diagnosis 1
• Monitor for signs of adrenal crisis in the first 2-4 weeks 1

Step 2: Levothyroxine (After 1 Week Minimum)

• Wait at least 1 week after starting hydrocortisone before initiating thyroid replacement 1
• Target free T4 in the upper half of the reference range 1
• Check free T4 at 2 and 4 weeks after starting levothyroxine 1
• Monitor feeding tolerance and weight gain 1

Step 3: Growth Hormone (Defer 2-3 Months)

• Growth hormone is NOT an emergency and should be deferred 1
• Consider initiation after 2-3 months of age once cortisol and thyroid replacement are optimized 1
• GH deficiency diagnosis in neonates is based on auxology, MRI findings, and low growth factor concentrations rather than dynamic testing 3

Critical Pitfall to Avoid

Never start thyroxine before hydrocortisone—this can trigger fatal adrenal crisis. 1 Starting thyroid hormone increases metabolic demand and accelerates cortisol clearance, which can precipitate acute adrenal insufficiency in an already cortisol-deficient patient 1.

Monitoring Requirements

In the acute phase (first 2-4 weeks):

• Watch for hypotension, hypoglycemia, and hyponatremia 1
• Assess feeding tolerance and weight gain 1
• Use free T4 (not TSH) to guide thyroid replacement in central hypothyroidism 1

Answer to the Question

The correct answer is A: Give hydrocortisone. This newborn requires immediate glucocorticoid replacement to prevent adrenal crisis and death. Thyroxine (option B) must wait at least 1 week, growth hormone (option C) should be deferred for months, and waiting to repeat labs (option D) is dangerous and inappropriate when the diagnosis is already established 1, 2.