Hormone Journal

Growth hormone deficiency

Also known as: GHD, adult GHD

Medically reviewed by Hormone Journal Editorial Team · Last reviewed 2026-05-22

Growth hormone deficiency (GHD) is a pituitary disorder affecting roughly 2–3 per 10,000 adults, causing fatigue, increased abdominal fat, reduced muscle mass, low mood, and elevated cardiovascular risk.

What it is

Growth hormone deficiency (GHD) is a condition in which the pituitary gland produces insufficient growth hormone (GH), affecting an estimated 2–3 per 10,000 adults and carrying significant consequences for body composition, bone density, cardiovascular health, and quality of life if left untreated. Also called adult GHD or AGHD, the condition is distinct from childhood GHD — where stunted linear growth is the dominant feature — and is frequently underdiagnosed because its symptoms overlap with depression, hypothyroidism, and general fatigue.

GHD can be classified along two axes. By onset, it is either childhood-onset (congenital or structural causes present from early life) or adult-onset (acquired, usually following pituitary damage). By scope, it is either isolated GHD (only GH is deficient) or part of panhypopituitarism (multiple pituitary hormone axes are affected). Pituitary adenomas and craniopharyngiomas together account for approximately 57% of adult-onset cases.

In Canada, diagnosis and treatment are managed through endocrinology, and recombinant human growth hormone (rhGH) is available by prescription. Coverage varies by province: some provincial drug benefit programs cover rhGH for confirmed adult GHD, but prior authorization is typically required and criteria differ across jurisdictions. Patients can clarify eligibility through their provincial formulary or a pharmacist.

Classification axisCategoryKey features
OnsetChildhood-onsetOften congenital or structural; GH treatment may have been stopped at final height
OnsetAdult-onsetAcquired; pituitary tumor, TBI, radiation, or surgery most common
ScopeIsolated GHDOnly GH axis affected
ScopePanhypopituitarismMultiple pituitary hormones deficient; GHD often the last to develop

Causes and mechanism

GH is secreted by somatotroph cells in the anterior pituitary in a pulsatile pattern, predominantly at night. It acts directly on tissues and indirectly through insulin-like growth factor 1 (IGF-1), which is produced by the liver in response to GH and mediates many of GH's anabolic effects. When GH output falls, IGF-1 drops, and the downstream effects on muscle, bone, fat metabolism, and mood follow.

The most common causes of adult-onset GHD are:

  1. Pituitary adenoma — the tumour itself, or the surgery and radiation used to treat it, can damage somatotroph cells. GHD is the most radiation-sensitive pituitary function.
  2. Craniopharyngioma — a tumour arising near the hypothalamus and pituitary stalk; a leading cause in both children and adults.
  3. Traumatic brain injury (TBI) — damage to the pituitary stalk or hypothalamic portal circulation. GHD is the most common pituitary hormone deficiency after moderate-to-severe TBI, estimated to affect 20–30% of survivors.
  4. Subarachnoid haemorrhage — disruption of pituitary blood supply.
  5. Cranial radiation — dose-dependent hypothalamic-pituitary axis damage; GH axis is affected at lower doses than other axes.
  6. Infiltrative and infectious diseases — sarcoidosis, Langerhans cell histiocytosis, tuberculosis.
  7. Idiopathic — no structural cause identified in a subset of patients.

Symptoms and diagnosis

Adult GHD produces a cluster of non-specific symptoms that are easy to attribute to other causes:

  • Persistent fatigue and reduced stamina
  • Increased central (abdominal) adiposity
  • Reduced lean muscle mass and strength
  • Reduced bone mineral density, raising fracture risk
  • Low mood, anxiety, and impaired sense of wellbeing
  • Cognitive slowing and poor concentration
  • Poor sleep quality
  • Elevated LDL cholesterol and unfavourable cardiovascular risk markers
  • Dry skin and reduced sweating

Diagnostic pathway:

Because GH is secreted in pulses and is undetectable for most of the day, a random serum GH level is not useful. The standard approach is:

  1. IGF-1 measurement — the primary screening test. A low IGF-1 in a patient with relevant clinical history and risk factors raises suspicion. IGF-1 must be interpreted against age- and sex-matched reference ranges; LifeLabs and Dynacare both offer IGF-1 testing in Canada.
  2. GH stimulation testing — required to confirm the diagnosis. The insulin tolerance test (ITT) is the gold standard: a peak GH below 3 µg/L during insulin-induced hypoglycaemia is diagnostic in most guidelines. The ITT requires medical supervision and is contraindicated in patients with seizure disorders or ischaemic heart disease. The glucagon stimulation test is a widely used alternative.
  3. Pituitary MRI — to identify structural causes.
  4. Full anterior pituitary panel — GHD frequently coexists with deficiencies of other pituitary hormones (TSH, ACTH, LH/FSH, ADH); all axes should be assessed.

Treatment options

The primary treatment for confirmed adult GHD is recombinant human growth hormone (rhGH), given as a once-daily subcutaneous injection, typically at bedtime to approximate the natural nocturnal GH surge. Dosing is individualized and titrated upward based on IGF-1 levels, symptom response, and side effect tolerance — not by weight, as weight-based dosing leads to over-treatment.

Documented benefits of rhGH replacement include:

  • Reduction in visceral fat and increase in lean body mass
  • Improved bone mineral density (effects on fracture risk take years to accrue)
  • Improved energy, exercise capacity, and quality-of-life scores
  • Favourable shifts in LDL cholesterol and cardiovascular risk markers

Common side effects — fluid retention, joint or muscle aches, carpal tunnel syndrome — are dose-dependent and typically resolve with dose reduction. Monitoring includes periodic IGF-1 measurements (to keep levels within the age- and sex-appropriate normal range), bone density scans, and cardiovascular risk factor review.

Where GHD results from a pituitary tumour, treating the tumour (surgically or with radiation) is the primary step; hormone replacement addresses residual deficiencies.

Canadian patients seeking assessment and prescription management can access endocrinology through referral from a family physician. Some virtual endocrinology and hormone-health platforms operating in Canada — including Felix, Maple, and others — may facilitate initial assessment, though formal GH stimulation testing requires in-person medical supervision.

When to see a clinician in Canada

Seek an endocrinology referral if you have:

  • A history of pituitary tumour, pituitary surgery, or cranial radiation
  • A history of moderate-to-severe traumatic brain injury with unexplained persistent fatigue, weight gain, or mood changes
  • A childhood diagnosis of GHD that was stopped at final height and has never been formally reassessed in adulthood (transition testing is recommended)
  • Unexplained significant fatigue, reduced exercise capacity, increased abdominal fat, and low mood alongside a known deficiency in another pituitary hormone

GHD is frequently missed after TBI and pituitary surgery. If you have experienced either and have not been tested, it is worth raising with your GP or requesting a referral to an endocrinologist.

Limitations and open questions

Research is still emerging on several aspects of adult GHD. The optimal GH stimulation test cut-off varies between guidelines and between stimulation agents, and there is no universal consensus on the best alternative to the ITT for patients in whom it is contraindicated. The long-term effect of rhGH replacement on fracture rates — as opposed to bone density — remains incompletely characterized. Evidence on GHD following mild TBI (as opposed to moderate-to-severe) is limited and inconsistent; routine screening after mild TBI is not currently recommended by most guidelines.

Health Canada has not issued a standalone clinical guidance document on adult GHD management; Canadian clinicians generally follow the Endocrine Society (2011) and AACE/ACE (2019) guidelines. Provincial pharmacare coverage criteria for rhGH in adults differ and are not uniformly published, so patients should verify eligibility directly with their provincial drug benefit program. The question of whether treating idiopathic adult GHD (no structural cause identified) produces the same benefits as treating structural GHD remains an area of active study.

FAQs

Is growth hormone deficiency only a childhood condition?

No. While GHD in children causes growth failure and is well recognized, it also occurs in adults and produces a distinct syndrome: fatigue, increased abdominal fat, reduced muscle mass, low mood, and elevated cardiovascular risk. Adult-onset GHD typically follows damage to the pituitary gland from a tumour, surgery, radiation, or traumatic brain injury. It is a recognized, treatable medical condition that is unfortunately underdiagnosed because its symptoms are non-specific and mimic depression, hypothyroidism, and burnout.

Can traumatic brain injury cause growth hormone deficiency?

Yes, and this connection is increasingly recognized. GHD is the most common pituitary hormone deficiency following moderate-to-severe traumatic brain injury, estimated to affect 20–30% of survivors. It frequently goes undetected because fatigue, cognitive difficulties, and mood changes are attributed entirely to the brain injury itself. Anyone with a history of moderate-to-severe TBI who has persistent, unexplained fatigue, weight gain, or difficulty concentrating should ask their physician about pituitary function testing.

How is adult GHD diagnosed — is it just a blood test?

Diagnosis requires more than a single blood test. Because GH is secreted in pulses and is undetectable for most of the day, a random GH level is not useful. The standard approach starts with an IGF-1 blood test — available through LifeLabs and Dynacare across Canada — and, if IGF-1 is low and clinical suspicion is high, proceeds to a GH stimulation test. The insulin tolerance test is the gold standard, with a peak GH below 3 µg/L being diagnostic, but it requires in-person medical supervision. The glucagon stimulation test is a common alternative for patients in whom the ITT is contraindicated.

Is growth hormone therapy safe for adults, and does it increase cancer risk?

When prescribed and monitored by an endocrinologist for confirmed GHD, rhGH replacement is generally considered safe. Side effects — fluid retention, joint or muscle aches, carpal tunnel syndrome — are dose-dependent and typically resolve with dose adjustment. Current evidence from long-term surveillance studies does not show that physiological GH replacement at doses titrated to keep IGF-1 within the normal range increases cancer risk. That said, rhGH is not appropriate for patients with active malignancy, and ongoing monitoring is standard practice.

Is growth hormone replacement covered by provincial drug plans in Canada?

Coverage varies by province and is not uniform. Some provincial drug benefit programs do cover recombinant human growth hormone for adults with confirmed GHD, but prior authorization is typically required and the eligibility criteria differ across jurisdictions. Patients should contact their provincial formulary directly — for example, the Ontario Drug Benefit program or BC PharmaCare — or ask their endocrinologist or pharmacist to clarify what documentation is needed. Without coverage, rhGH can be expensive, so confirming benefit eligibility before starting treatment is an important practical step.

Sources

All glossary termsUpdated 2026-05-22