Where to Buy IGF-1 LR3: 7 Purity and Identity Checks for a Compound With No Verifiable Reference Mass

Every vendor page for IGF-1 LR3 quotes the same molecular weight, and we could not find a source for it. That matters at the point of purchase, because mass spectrometry is the one test that would tell you what is in the vial.

This page is the sourcing walkthrough. IGF-1 LR3 sits in the growth hormone peptides category, vendor listings and per-milligram pricing sit on the IGF-1 LR3 compound page, and the full evidence picture — the unsourceable specification, the approved parent drug's label, the zero registered trials — is in IGF-1 LR3: the molecular weight nobody can source. Read that one for the science. Read this one before you pay.

What is IGF-1 LR3, and why does source quality matter?

IGF-1 LR3 is a recombinant analogue of human insulin-like growth factor 1, built on a parent chain of 70 residues, three intramolecular disulfide bridges and 7,649 daltons per FDA's mecasermin label, with an N-terminal extension added and a substitution at position 3. Source quality matters for one specific reason: the specification vendors quote for the finished analogue — 83 amino acids, roughly 9,111 daltons — has no source we could find, so the identity test has nothing authoritative to check against.

Two rows in that table decide how you shop. The verified ones describe the parent molecule and the design rationale, and both are solid: native IGF-1 in blood is almost entirely bound to IGF binding proteins, principally IGFBP-3, and the LR3 modifications are intended to reduce that binding so more of the molecule stays free. FDA's own mecasermin label puts numbers on how much binding protein governs clearance — 0.04 L/hr/kg at 0.5 micrograms/mL of IGFBP-3, and 0.01 L/hr/kg at 3 micrograms/mL — a four-fold difference driven by binding protein alone. There is nothing fraudulent about the concept.

The unsourceable rows describe the thing you are actually buying. A full-text Europe PMC search for the extension sequence on those vendor pages returns zero hits across the indexed biomedical literature, and the founding paper describes something different. The quoted half-life appears on our own compound page and we could not source it independently either, which is why this page flags it rather than repeating it.

That the product is recombinant has a practical consequence worth carrying into the checkout page. An 80-odd-residue disulfide-bonded protein sits at or beyond the edge of solid-phase peptide synthesis, so this is not a compound anyone makes on a peptide synthesiser — folding three correct disulfide bridges is a manufacturing problem, not a coupling problem, and how peptides are made is the relevant background. The truncated sibling, IGF-1 DES, sits in the same position with the same absence of human data.

What is the regulatory status of IGF-1 LR3?

IGF-1 LR3 is approved nowhere, and ClinicalTrials.gov returns zero registered studies for it. As of August 2026 no compounding route exists: LR3 appears on neither of FDA's compounding tables, and as a distinct molecule rather than a component of any approved drug it satisfies none of the three statutory routes for 503A compounding. WADA prohibits it at all times under section S2.3, which names "Insulin-like growth factor 1 (IGF-1, mecasermin) and its analogues."

We enumerated both tables on the FDA bulk drug substances page current 22 April 2026 in full — 14 substances in active Category 2, 17 in the nominated-but-withdrawn table — because absence from a list is only meaningful if you have read the list. No member of the IGF-1 family is on either. That absence is not clearance. Because mecasermin is an approved product, plain IGF-1's status under the component-of-an-approved-drug prong is arguable; LR3 and DES are distinct molecules, so the argument does not reach them. Our FDA peptide regulation timeline tracks where each determination stands, and are peptides legal covers the country-by-country picture.

On sport, this is a named class rather than a catch-all inference. Section S2.3, "Growth factors and growth factor modulators," prohibits "Insulin-like growth factor 1 (IGF-1, mecasermin) and its analogues" and "Mechano growth factors (MGFs)," alongside FGFs, HGF, PDGF, thymosin-β4 and VEGF, at all times. "And its analogues" captures LR3 and DES without ambiguity. A 2022 method paper on probing for peptidic drugs in blood samples names "long-R3-IGF-I, R3-IGF-I and Des 1–3-IGF-I" specifically, so testing laboratories are looking for these compounds by name — a materially different position from being covered by a category, as do peptides show up on drug tests explains.

The approved parent drug is the only member of this family with numbers attached to it, and buyers should know what those numbers are. Mecasermin (INCRELEX) is BLA 021839, approved 30 August 2005, sponsored by Ipsen, deemed a BLA on 23 March 2020, indicated for growth failure in paediatric patients 2 years and older with severe primary IGF-1 deficiency. Its terminal half-life is 5.8 hours after a single 0.12 mg/kg subcutaneous dose.

Two rows there are corrections rather than gaps, and one of them corrects our own earlier working notes. Increlex does not carry a boxed warning. We checked three independent label sources — the Ipsen label revised July 2025, the Eton Pharmaceuticals label revised October 2025, and the FDA-approved label PDF revised January 2019 — and hypoglycaemia is Warnings and Precautions section 5.1. The correction cuts both ways, because the numbers in 5.1 are not reassuring: hypoglycaemia was reported by 30 subjects (42%), five had severe episodes requiring assistance, and four experienced hypoglycaemic seizures or loss of consciousness, under paediatric endocrinology supervision with glucose monitoring. Malignant neoplasia is a contraindication on that label, not merely a warning.

Why can't mass spectrometry confirm IGF-1 LR3's identity?

Mass spectrometry cannot confirm IGF-1 LR3's identity because no reference mass exists that we could verify. A full-text Europe PMC search for the extension sequence quoted on vendor pages, MFPAMPLSSLFVN, returns zero hits, and the founding 1992 paper describes the first 11 amino acids of methionyl porcine growth hormone — eleven, not thirteen, which gives 81 residues rather than 83. A second failure sits behind the first: three disulfide bridges must pair correctly, and a misfolded protein has exactly the same mass.

We are not saying the market specification is wrong. We are saying we could not find a source for it, and that the primary paper appears to disagree with it. Those are different statements, and the difference is the whole of a buyer's problem here: a wrong number can be corrected, while an unsourceable number cannot be checked at all. The founding group's own words are that their analogues comprise "an IGF-I sequence and the first 11 amino acids of methionyl porcine growth hormone." Not one paper in the indexed literature contains the thirteen-residue sequence that vendors quote.

That is a different and worse position than a compound whose mass is known but hard to measure. Here, a certificate of analysis reporting a mass has nothing authoritative to be checked against, because the usual comparator is the same unsourced 9,111 daltons circulating on the vendor pages you are trying to audit.

Read the first two rows together. A truncated or misfolded product may pass inspection, because an 80-residue chain has roughly 80 coupling or expression steps and three disulfide bonds that must form in the correct pairing, and mass spectrometry cannot see pairing at all. Substitution is the other live route: native IGF-1 at 7,649 daltons is a substantial mass difference and easily detected if you know the LR3 target, but without a verified target an MS result reading "approximately 9,000 daltons" is not an identity confirmation. For the underlying methods, see mass spectrometry for peptides, what HPLC testing can and cannot tell you and how to read peptide lab test results.

7 things to check before ordering IGF-1 LR3

Seven checks cover IGF-1 LR3, and the first is unusual enough to state plainly: ask the vendor where the 9,111-dalton figure comes from, because we could not source it. After that come a mass spectrum that at minimum excludes native IGF-1 at 7,649 daltons, whatever the vendor will say about disulfide pairing, the words "recombinant" and an expression system on the page, third-party HPLC read against the platform's 98.51% average, fill quantity as a separate line, and a shop and price check.

1. Ask where the 9,111-dalton figure comes from, and treat silence as an answer. This check runs on the vendor's paperwork rather than on the vial, and it is first because everything downstream depends on it. A full-text Europe PMC search for the quoted extension sequence returns zero hits, so a vendor who can produce a primary source has told you something genuinely new, and a vendor who repeats the number without one has told you they copied a specification rather than characterised a product. Neither answer is a purity question.

2. A batch-matched mass spectrum that at minimum excludes native IGF-1 at 7,649 daltons. You cannot confirm LR3 by mass, but you can exclude the most plausible substitution, because 7,649 daltons is FDA's figure from an approved label and is far enough from any plausible LR3 mass to be unambiguous. Insist the result is tied to your lot rather than a specimen certificate from an earlier batch, which red flags in peptide certificates of analysis covers, and treat "approximately 9,000 Da" as a measurement rather than a confirmation.

3. Ask what the vendor does about disulfide pairing, and expect nothing. Three intramolecular bridges must form in the correct pairing for the molecule to work, incorrectly folded IGF-1 has the same mass as correctly folded IGF-1 and is biologically inactive, and no routine certificate of analysis reports folding at all. The point of asking is not to obtain the document. It is to know, before you pay, that the most likely defect in an 80-residue recombinant protein is the one defect nothing on your certificate will detect.

4. The word "recombinant" and a named expression system on the product page. IGF-1 LR3 is a recombinant fusion protein — Francis and colleagues expressed it in E. coli in 1992 and a 2023 paper describes Pichia pastoris — and an 80-odd-residue disulfide-bonded protein sits at or beyond the edge of solid-phase peptide synthesis. A page describing LR3 as a synthetic peptide made by SPPS is describing a manufacturing route that does not produce this molecule, which is a characterisation failure visible before any money changes hands.

5. Third-party HPLC from a named laboratory, read against the platform record and read for its limits. The Purity Index records 98.51% average across 125 tests with individual results running 94.29% to 99.90% (verified August 2026), so a vendor claiming a house standard well above that floor should be able to produce a named laboratory's document rather than their own, as third-party peptide testing labs sets out. Then hold the ceiling in mind: HPLC measures homogeneity, and a homogeneous sample of misfolded protein returns a clean chromatogram.

6. Fill quantity as its own line, plus an LAL endotoxin result on the same batch. Quantity variance on this compound runs +1% to +72%, and purity is a proportion while net content is a quantity — the distinction net peptide content exists to make. Ask for a quantitative content figure separately from the purity figure. Ask for an LAL endotoxin result on the same batch too, because it is rarely reported on this compound and an absent result means untested rather than passed.

7. Shop record and price, plus what no certificate can establish. Trust scores weight community reviews and independently verified HPLC purity equally at 50% each, so read community-verified shop reviews alongside the documents and screen the vendor with what to look for in a peptide shop. Price data shows 42 shops in stock at a median of $75.00/mg (verified August 2026). Then note the ceiling on all seven checks: no document available to a buyer establishes that this vial contains the molecule its label names.

Rows one, three and four contain no laboratory result at all. They are read off the vendor's paperwork and product page before you pay, and on this compound they carry more weight than the rows that do, because the laboratory rows cannot reach the two failure modes that matter most here.

Where does IGF-1 LR3 rank on Peptigrity's lab test database?

The Purity Index records IGF-1 LR3 at 98.51% average across 125 tests (verified August 2026) from ILS Laboratories, Kovera, Bioviridian and Liquilabs, across 220 verified shops — the lowest purity index of any well-tested compound on this platform. Individual results run 94.29% to 99.90%, quantity variance runs +1% to +72%, and price data shows 42 shops in stock, median $75.00/mg, lowest $30.00/mg on a 1 mg vial (verified August 2026).

One vendor's June 2026 sample tested 72% over label. A 72% overage is not generosity. It is direct evidence that fill quantity is uncontrolled, and on a compound whose parent drug's signature adverse effect is hypoglycaemia — 42% incidence in a monitored paediatric population — a 72% dosing error has an obvious mechanism for harm. That is why the fill-quantity row in the table above sits alongside the identity rows rather than below them.

Read the price scale as information rather than as a warning. $75 per milligram against $3–5 for typical synthetic peptides is roughly what a recombinant, disulfide-folded protein costs to make properly — and it is also a strong incentive to cut corners, which is the reason the fill-quantity and folding checks matter more here than the purity check. Those figures exclude shipping, taxes and customs, coupon codes, bulk tiers, multi-vial kits and account-gated pricing.

Every result behind the purity average is browsable in the independent lab tests database, batch by batch, and trust scores weight community reviews and independently verified HPLC purity equally, at 50% each, with no financial relationship influencing the ranking. Those figures sit inside a platform tracking 530 shops and 11,852 independent lab tests across 118 peptides, with 1,283 community reviews (verified August 2026).

The dataset carries a standing caveat with unusual force on this compound. Published certificates are the ones vendors chose to publish, which makes the sample selection-biased rather than a random market survey — and here a certificate reporting HPLC purity does not establish that the vial contains IGF-1 LR3 at all.

The trial that would settle this has a first row that is not a trial requirement at all.

The first row blocks the rest. You cannot run a trial of a molecule whose specification is not established, and no sponsor has published one — which means the requirement a trial would place on its own investigational material is a requirement no buyer can currently meet either.

Frequently Asked Questions

What purity standard should IGF-1 LR3 meet?

The platform average is 98.51% across 125 tests with individual results from 94.29% to 99.90%, and a 94.29% floor on an injectable is a real signal rather than a rounding artefact. Treat that as the benchmark for the HPLC line, then treat the HPLC line as the least informative document in the file. Purity reports the proportion of a single species, not which species, and on a misfolded recombinant protein it reports a clean chromatogram.

How much does IGF-1 LR3 cost, and why is it so much more expensive than other peptides?

Price data shows 42 shops in stock at a median of $75.00/mg and a low of $30.00/mg on a 1 mg vial (verified August 2026), against $3–5/mg for typical synthetic peptides. The gap is not markup for its own sake: an 80-odd-residue disulfide-bonded protein has to be expressed in a living system and folded correctly, which costs what it costs. Compare within a single vial-size band, since fixed per-vial costs push per-milligram figures down as fill size rises.

Is IGF-1 LR3 legal to buy, and is it banned in sport?

It is not approved for human use anywhere, and as of August 2026 no compounding route exists — it appears on neither of FDA's compounding tables, and as a distinct molecule rather than a component of an approved drug it satisfies none of the three statutory routes for 503A compounding. On sport it is explicitly prohibited: WADA section S2.3 covers "insulin-like growth factor 1 (IGF-1, mecasermin) and its analogues" at all times, and published doping-control methods name long-R3-IGF-I as an analyte directly.

How do I know my vial is really IGF-1 LR3?

You cannot fully establish it, and that is the honest answer rather than a cautious one. Mass spectrometry confirms identity by comparison against an authoritative expected mass, and for LR3 no such figure exists that we could verify. What you can do is exclude the most plausible substitution — native IGF-1 at 7,649 daltons, FDA's figure from the mecasermin label — and note that even a matching mass says nothing about whether the three disulfide bridges paired correctly.

Does the 20-plus-hour half-life figure tell me how to dose it?

No. That figure appears on our own compound page and we could not source it independently, so it is flagged here rather than repeated as fact. No human pharmacokinetic study of IGF-1 LR3 has ever been published and ClinicalTrials.gov returns zero registered studies, so no dosing interval derives from measured human data. The peptide dosing calculator and the reconstitution calculator convert a chosen dose into a syringe volume; they are arithmetic, not a recommendation.

If the purity average is 98.51%, why is this the platform's lowest-ranked well-tested compound?

Because the ranking reflects the whole certificate rather than the headline figure. Individual results run down to 94.29%, quantity variance reaches +72% with a June 2026 sample on record at that level, and endotoxin results are rarely reported. Underneath all of it, the purity number describes homogeneity on a molecule whose reference mass we could not verify — so the one figure that looks reassuring is also the one figure that cannot establish what is in the vial.

Browse the growth hormone peptides category, or our complete peptide guide with 118 compounds (verified August 2026). For reconstitution and per-injection volume, use the peptide dosing calculator alongside the reconstitution calculator. Compare shops through independent lab tests and community-verified shop reviews.

This article is for educational and informational purposes only and does not constitute medical advice. Peptides discussed may be investigational compounds not approved by the FDA (or equivalent regulators in your jurisdiction) for human use. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.