Clinician reference tool — not medical advice. This is a clinical decision-aid intended for healthcare professionals: it gives deterministic suggestions to think with, not a diagnosis or a prescription. If you’re a patient, you’re welcome to look around — but please review anything here with your own doctor; it isn’t a substitute for personalized medical care.
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IGF-1 (insulin-like growth factor 1)

Metabolic · specimen: blood

Indicated in specific situations

Also called: insulin-like growth factor 1, somatomedin C, IGF-1 test

Chart note

Pick Ordered or Not ordered to see the note.

Indicated when

  • Clinical suspicion of acromegaly or gigantism: acral enlargement, coarsened facial features, new or worsening sleep apnea, jaw prognathism, widened tooth spacing, or other features prompting biochemical assessment on the Endocrine Society's acromegaly guideline pathway [1]
  • Suspected growth hormone deficiency in a child or adult, evaluated together with dynamic GH stimulation testing [1]

Not indicated when

  • Investigating fatigue, low energy, poor exercise recovery, or general 'anti-aging'/wellness interest in growth hormone status, without features suggestive of acromegaly or another pituitary disorder

Why not

IGF-1 is a useful biochemical marker within the specific diagnostic pathway for acromegaly and growth hormone disorders, guided by clinical features; the Endocrine Society's acromegaly guideline frames biochemical assessment as part of an evidence-based approach to that diagnosis, not as a general wellness or fatigue marker [1]. Ordering it without a reason to suspect a growth-hormone-axis disorder produces a result with no clear next step and can prompt unnecessary pituitary imaging.

Better first step

If there are no features suggesting acromegaly or growth hormone deficiency (acral or facial change, new sleep apnea, a growth concern in a child), IGF-1 is not the right first test for fatigue or general wellness concerns; more common causes of fatigue should be investigated first.

Typical ND rationale

An ND may order IGF-1 reasoning that it reflects overall growth hormone activity and could explain fatigue, poor recovery from exercise, or concerns about aging and muscle mass.

Where the ND is right

The ND is right that IGF-1 is a genuinely useful, guideline-endorsed test, but specifically for suspected acromegaly or growth hormone deficiency, conditions with recognizable discriminating features. Where a patient has those features, ordering IGF-1 is appropriate and shouldn't be delayed [1].

Ontario coverage & CONO orderability

OHIP status
uninsured
IGF-1 does not appear by name anywhere in the 2026 Schedule of Benefits for Laboratory Services, consistent with docs/research/ontario-coverage.md's listing of IGF-1 among tests absent from the community Schedule. Absence from the community Schedule doesn't rule out coverage through another pathway (for example, a specialized or hospital endocrine laboratory), so this is recorded as unverified. ND-ordered testing is patient-paid regardless (Reg. 552 s.22). Coverage update (reconciliation pass): LifeLabs' Non-OHIP Billable Test List (2025, republished by an Ontario hospital lab) lists this test as patient-paid in community labs. This is secondary evidence, not a ministry statement. Hospital-lab funding in specialist care (e.g. IGF-1 under endocrinology) was not checked.
CONO orderable
Yes — CONO list #80
CONO list item 80, blood: 'Insulin-Like Growth Factor 1.'

Linked conditions

Counselling script

“IGF-1 is a genuinely useful test, but specifically when there are features suggesting too much or too little growth hormone, like changes in hand, foot, or facial size, new sleep apnea, or a growth concern in a child. Since I'm not seeing those features today, I wouldn't add IGF-1 for fatigue alone; let's look at more common causes instead. If those specific features show up, IGF-1 is exactly the right test to order.”

Revisit if

  • New acral or facial change, new sleep apnea, jaw prognathism, or widened tooth spacing
  • Growth concern or suspected growth hormone deficiency in a child

References

  1. [1]Endocrine Society (2014). Acromegaly: An Endocrine Society Clinical Practice Guideline. linkolder guidelineEndocrine Society acromegaly guideline addresses appropriate biochemical assessment (including IGF-1) as part of an evidence-based diagnostic approach
  2. [2]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026). linkCommunity lab tests are insured only when ordered under the Schedule by an authorized prescriber
  3. [3]Government of Ontario (e-Laws) (2026). Health Insurance Act, R.R.O. 1990, Reg. 552: General, s. 22 (insured laboratory services). linkA lab test is insured only when ordered by a physician, midwife, or NP who has clinically assessed the patient
  4. [4]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026). linkTests ordered by anyone other than an authorized provider, including NDs, are not insured services
  5. [5]LifeLabs (republished by Norfolk General Hospital laboratory) (2025). LifeLabs Non-OHIP Billable Test List (republished by Norfolk General Hospital laboratory, effective 2025). linkListed as a non-OHIP (patient-paid) test at LifeLabs Ontario, 2025
Evidence notes

The Katznelson 2014 Endocrine Society acromegaly guideline's PubMed abstract does not itself name IGF-1; the abstract's conclusion refers generally to 'the appropriate biochemical assessment' as part of the guideline. That IGF-1 specifically is the recommended first-line biochemical marker for acromegaly is well-established clinical knowledge but was not confirmed by this session's own read of the guideline's full text (paywalled; not fetched within budget), so it is flagged here for the reviewer rather than treated as independently verified beyond the abstract's general statement. No condition id for acromegaly/pituitary disorders exists yet in docs/plan.md's condition batches; linked_conditions uses 'tired' as the closest existing entry point (fatigue is often what prompts an ND visit and IGF-1 order), but a dedicated pituitary/acromegaly condition page is not currently planned and may be out of scope for this program given how rare the condition is.