Does stress increase growth hormone secretion?

Does Stress Increase Growth Hormone?

Yes, stress does increase growth hormone (GH) secretion, but the response depends critically on the type, intensity, and duration of the stressor, with acute severe stressors producing robust GH elevations while commonplace daily stressors typically do not significantly alter GH levels.

Mechanism of Stress-Induced GH Secretion

The stress-induced increase in GH occurs through hypothalamic pathways that are distinct from but coordinated with the HPA axis response 1:

• Acute severe stress triggers a 3.5-fold increase in growth hormone-releasing hormone (GHRH) secretion into hypophysial portal blood, which directly stimulates pituitary GH release 2
• The hypothalamus simultaneously increases somatostatin secretion during stress, though GHRH elevation predominates to produce net GH increases 2
• This neuroendocrine response occurs concomitantly with corticotropin-releasing hormone (CRH) and cortisol elevation, indicating coordinated activation of multiple stress pathways 2

Type and Intensity of Stressor Matters

The GH response is highly dependent on stressor characteristics, with important clinical implications 3, 4:

Stressors That Reliably Increase GH:

• Hypoglycemia produces robust and repeatable GH responses, even when applied sequentially, as the metabolic threat overrides normal feedback inhibition 3
• Acute physical stress (isolation-restraint, intense exercise) induces rapid and significant GH elevation in most individuals 2, 3
• Severe metabolic challenges including prolonged food restriction, pregnancy, and obesity trigger substantial GH increases to restore homeostasis 4

Stressors With Minimal GH Effect:

• Commonplace psychological stress (academic examinations) does not significantly alter mean daytime or nocturnal GH concentrations despite elevated perceived stress scores 5
• Sequential identical stressors (repeated exercise or hyperthermia) show attenuated or absent GH responses due to feedback inhibition 3

Clinical Context: Low Energy States

In conditions of metabolic stress, particularly low energy availability, GH responses become paradoxically altered 6:

• Energy deficiency in female athletes causes increased GH levels but with concurrent growth hormone resistance, resulting in decreased IGF-1 despite elevated GH 6
• Low energy availability produces a constellation of hormonal changes including increased cortisol and increased GH (with resistance), alongside decreased IGF-1 6
• This GH/IGF-1 dysregulation may contribute to stunted linear growth in energy-deficient individuals 6

Physiological Purpose of Stress-Induced GH

The metabolic effects of stress-induced GH serve specific homeostatic functions 4:

• Glucose mobilization: GH increases blood glucose levels and induces insulin resistance to preserve glucose for critical organs during metabolic challenges 4
• Fat mobilization: GH stimulates lipolysis to provide alternative energy substrates when glucose availability is threatened 4
• Hunger stimulation: GH increases hunger perception and food intake to accelerate recovery of energy stores after energy-demanding activities 4
• Metabolic coordination: GH affects neuronal populations controlling metabolism and stress response to orchestrate multiple adaptations that restore homeostasis 4

Important Clinical Caveats

Several factors complicate the interpretation of stress-GH relationships:

• Feedback mechanisms: The GH response to sequential stress stimuli depends on the stimulus type, with hypoglycemia overcoming usual feedback inhibition while exercise and hyperthermia do not 3
• Seasonal variation: GH secretion shows significant seasonal effects, with consistently higher daytime and nocturnal levels in fall compared to spring, independent of stress 5
• Synergistic effects: Psychological stress combined with pharmacological stimuli (TRH) produces significantly higher GH responses than either stimulus alone, suggesting potentiation rather than simple additive effects 7
• Age and duration: In acromegaly (chronic GH excess), aging and long duration of exposure to elevated GH are important determinants of cardiac abnormalities, suggesting cumulative effects of sustained elevation 6

Diagnostic Implications

When evaluating patients with suspected GH disorders 6:

• Stress-related prolactin elevation must be excluded through serial measurements at 20-60 minute intervals using an indwelling cannula, as prolactin (not GH) rises acutely with venipuncture stress 6
• Age-specific and sex-specific reference ranges are essential for interpreting GH and IGF-1 levels, as normal values vary substantially across development 6
• Testing for GH excess or deficiency is indicated in patients with dilated cardiomyopathy who have other signs and symptoms of those clinical disorders 6