Laboratory Monitoring in Panhypopituitarism on Hormone Replacement Therapy

Initial Baseline Assessment

• The American College of Endocrinology recommends obtaining a complete pituitary axis evaluation, including 9 AM cortisol and ACTH, TSH and free T4, LH, FSH, testosterone, estradiol, IGF-1, prolactin, glucose, and HbA1c, before initiating hormone replacement therapy, with a strength of evidence level of high 1, 3
• The Endocrine Society suggests assessing thyroid axis with TSH and free T4, gonadal axis with LH, FSH, testosterone, and estradiol, and growth hormone status with IGF-1, with a strength of evidence level of moderate 1, 3, 2

Monitoring Schedule After Initiating Replacement

Thyroid Function Monitoring

• The American Thyroid Association recommends checking TSH and free T4 every 1-2 weeks initially after starting thyroid hormone replacement, with a strength of evidence level of high 1, 3
• The Endocrine Society suggests continuing frequent monitoring until stable, then transitioning to routine follow-up, with a strength of evidence level of moderate 1

Adrenal Function Monitoring

• The American College of Endocrinology recommends monitoring early morning ACTH and cortisol monthly for the first 6 months, every 3 months for the next 6 months, and every 6 months thereafter, with a strength of evidence level of high 2

Growth Hormone Axis

• The Endocrine Society suggests monitoring IGF-1 levels at regular intervals if on growth hormone replacement, with a strength of evidence level of moderate 2

Gonadal Axis

• The American College of Endocrinology recommends monitoring testosterone levels in men and estradiol in premenopausal women periodically to ensure adequate replacement, with a strength of evidence level of high 1, 3, 2

Metabolic Parameters

• The American Diabetes Association suggests regular glucose and HbA1c monitoring to assess glycemic control, with a strength of evidence level of high 2

Critical Interpretation Principles

Central Hypothyroidism Pattern

• The Endocrine Society suggests that low free T4 with low or normal TSH is indicative of central hypothyroidism, with a strength of evidence level of moderate 2

Central Adrenal Insufficiency Pattern

• The American College of Endocrinology recommends that low cortisol with low or normal ACTH is indicative of central adrenal insufficiency, with a strength of evidence level of high 2

Hypogonadotropic Hypogonadism Pattern

• The Endocrine Society suggests that low testosterone or estradiol with low or normal FSH and LH is indicative of hypogonadotropic hypogonadism, with a strength of evidence level of moderate 2

Essential Clinical Pitfalls to Avoid

• The American College of Endocrinology recommends never starting thyroid hormone replacement before ensuring adequate cortisol replacement, with a strength of evidence level of high 1, 3, 2
• The Endocrine Society suggests not using TSH alone to guide thyroid replacement dosing in central hypothyroidism, with a strength of evidence level of moderate 2
• The American College of Endocrinology recommends ensuring patient education on "sick day rules" and providing prescription for intramuscular steroids for emergency use, with a strength of evidence level of high 1, 3