A 28-year-old man stops his testosterone cycle. Three months later, his blood work looks normal — total testosterone 14 nmol/L, LH and FSH in range. His doctor tells him everything recovered. But a biomarker almost no one measures tells a different story: his Leydig cells — the testosterone factories inside his testicles — are permanently damaged. His INSL3 sits at 0.39 µg/L, right at the threshold of Leydig cell insufficiency. The hormone his body makes today hides a capacity his body has lost.
This is the reality of Prolonged Post-Androgen Abuse Hypogonadism — PPAAH — a condition that finally received a formal name and diagnostic criteria in 2025. It describes what happens when the HPG axis doesn't fully recover after anabolic-androgenic steroid (AAS) use, and it reveals that "normal" blood work can mask serious, lasting damage.
The Scale of the Problem
Anabolic steroid use is not rare. A 2014 meta-analysis by Sagoe and colleagues across 187 studies found a global lifetime prevalence of 6.4% in males — roughly 1 in 16 men. Among recreational gym-goers, the figure climbs to 18–20%. An estimated 3–4 million American males aged 13–50 have used AAS, with 30–35% at doses high enough to risk withdrawal symptoms.
No updated global meta-analysis has been published since 2014, despite widespread reports of rising use driven by social media, telehealth testosterone prescribing, and a cultural shift toward physique optimization. The epidemic is growing, but the epidemiology hasn't caught up.
What Happens During a Cycle
When a man takes exogenous testosterone or other AAS, the body detects supraphysiological androgen levels and shuts down its own production. The hypothalamus stops releasing GnRH. The pituitary stops releasing LH and FSH. The testes, deprived of their stimulatory signals, go dormant.
The HAARLEM study — a landmark prospective cohort of 100 male amateur athletes in the Netherlands — documented what this looks like in practice:
- During the AAS cycle, 77% had sperm counts below 40 million
- 66% were oligo- or azoospermic at the end of the cycle
- Every subject reported at least one negative health effect
- Four subjects experienced serious adverse events: congestive heart failure, acute pancreatitis, suicidal ideation, and exacerbation of ulcerative colitis
The damage isn't limited to reproductive function. During active use, LDL cholesterol rises, HDL crashes, blood pressure increases, and the heart begins to remodel. These cardiovascular effects have consequences that extend far beyond the cycle.
The Recovery Myth
The conventional wisdom in bodybuilding communities is straightforward: you cycle off, maybe run some post-cycle therapy (PCT), and your hormones bounce back. The HAARLEM data tells a more complicated story.
Three months after stopping AAS:
- Testosterone levels had normalized in most men
- But sperm counts were still 61.7 million below baseline
At one year:
- 11% still had low testosterone
- 34% still had sperm counts below 40 million
- Prior AAS users recovered more slowly than first-time users
- Estimated full sperm recovery: 56 weeks for first-time users, 69 weeks for repeat users
So testosterone recovers relatively quickly — usually within 3 months. But fertility recovery lags significantly, and prior use makes each subsequent recovery slower. This alone undermines the "just cycle off" narrative. But the real revelation came from looking deeper than testosterone.
INSL3: The Biomarker That Reveals What Testosterone Hides
Insulin-like factor 3 (INSL3) is a hormone produced constitutively by mature Leydig cells — the same cells that make testosterone. But unlike testosterone, INSL3 isn't pulsatile. It doesn't surge and crash with circadian rhythms. Its diurnal variation is only ±11%, compared to ±26% for testosterone. It reflects something more fundamental: the number and maturity of functional Leydig cells, not just their momentary output.
Think of it this way: testosterone tells you how hard the factory is working right now. INSL3 tells you how many machines the factory actually has.
The reference range established by Anand-Ivell (2024) from the EMAS cohort of 3,369 men sets a Leydig cell insufficiency threshold at ≤0.4 ng/mL. Below this, even if testosterone appears normal, the Leydig cell population is meaningfully compromised. INSL3 declines about 15% per decade from age 35, shows no ethnicity effect, and has good inter-assay concordance — making it an ideal clinical biomarker. Except almost no one orders it.
What INSL3 Shows in Former Steroid Users
Rasmussen and colleagues (JCEM, 2021) measured INSL3 in 44 controls, 46 current AAS users, and 42 former users (median 32 months post-cessation):
| Group | INSL3 (µg/L) | Interpretation |
|---|---|---|
| Controls | 0.59 | Normal Leydig cell capacity |
| Former users (~2.5 years post) | 0.39 | Right at insufficiency threshold |
| Current users | 0.04 | Near-complete suppression |
The former users' median INSL3 of 0.39 µg/L sits right at the Leydig cell insufficiency threshold. Approximately half of former users fell below 0.4 ng/mL — detectable Leydig cell damage even when their testosterone appeared "normal."
Crucially, cumulative AAS duration correlated with reduced INSL3 (p=0.022). Longer use means more damage. Neither testosterone nor INSL3 had fully recovered even 2.5 years after cessation. Inhibin B normalized by ~21 months, LH by ~12 months — but the Leydig cells themselves did not.
The hCG Stimulation Test Confirms It
Bulut and colleagues (JCEM, 2025) took this further. They gave former AAS users (approximately 2 years post-cessation) an hCG stimulation test — essentially asking: if we send the strongest possible signal to your testicles, can they respond?
The answer was no. Former users showed:
- Blunted testosterone response to hCG stimulation
- No rise in 17-OHP or estradiol (steroidogenic pathway not engaging)
- Persistently reduced INSL3
- Normal GnRH stimulation response (pituitary is fine)
The problem is testicular, not central. The pituitary works. The hypothalamus works. The Leydig cells are damaged. And this damage persists years after stopping.
PPAAH: A Diagnosis Takes Shape
In July 2025, van Os, Smit, Bond, and de Ronde published a landmark paper in Frontiers in Endocrinology proposing a standardized diagnosis for this condition: Prolonged Post-Androgen Abuse Hypogonadism (PPAAH).
Diagnostic Criteria
- Definition: Persistent hypogonadism ≥6 months after cessation of ≥150 mg/week AAS for ≥6 months
- Biochemical marker: Fasting morning free testosterone <225 pmol/L (65 pg/mL)
- Symptom requirement: ≥1 hypogonadal symptom
- Exclusions: Other causes ruled out (labs + pituitary MRI)
A critical insight from the van Os paper: PPAAH typically presents as hypogonadotropic (low LH/FSH) rather than hypergonadotropic — even though INSL3 data shows Leydig cell damage exists. This means both central and peripheral damage coexist. The hypothalamus and testes are both affected, but the central dysfunction dominates the biochemical picture.
Why Free Testosterone, Not Total?
AAS suppress SHBG — the protein that binds and carries testosterone in the blood. This suppression persists long after cessation. Handelsman (2022) showed that SHBG remained significantly lower in testosterone-treated men throughout 64 weeks post-injection. When SHBG is low, total testosterone looks artificially normal because more testosterone is "free" — creating a false sense of recovery. Free testosterone is the better diagnostic marker for PPAAH because it isn't confounded by this SHBG artifact.
The Seven Mechanisms
The van Os paper explores seven potential mechanisms for PPAAH, finding four plausible and three unlikely:
Plausible:
- Prolonged androgen depot activity — long-acting esters can continue suppressing the axis for months after the "last injection"
- Hypothalamic-pituitary alterations — prolonged supraphysiological androgens may durably alter KNDy neuron function (they express androgen and estrogen receptors)
- Testicular damage — Leydig cell dedifferentiation from prolonged LH deprivation; adult Leydig cells do not divide after full maturation, so damage is permanent
- Genetic predisposition — some men may carry subclinical GnRH pathway variants that make their axis more vulnerable to disruption
Less likely:
- SHBG suppression as sole explanation (contributes but doesn't explain symptoms)
- Ongoing undisclosed use (should be considered but doesn't explain all cases)
- Unrelated coincident pathology
The Fragile Axis Connection
The genetic predisposition mechanism connects directly to what I've previously described as the fragile axis hypothesis. The core idea: men who carry subclinical variants in GnRH pathway genes (GNRHR, KISS1R, TAC3, TACR3, and others) have reduced KNDy neuron buffer capacity. Under normal conditions, they're fine — you need to lose approximately 80% of KNDy neuron function before clinical hypogonadism manifests. But under the extreme stress of prolonged supraphysiological androgen exposure, these men may be the ones whose axis breaks and doesn't recover.
This would explain a persistent clinical puzzle: why do some men recover fully from identical AAS regimens while others develop PPAAH? Same drug, same dose, same duration — different outcomes. The fragile axis model predicts exactly this pattern. The van Os paper lists genetic predisposition as one of their four plausible mechanisms but doesn't provide the mechanistic detail. The evidence from Caronia (NEJM, 2011) — showing 12.7% of women with functional hypothalamic amenorrhea carry rare CHH variants — and Bonomi (2019) — showing enrichment in adult-onset isolated hypogonadotropic hypogonadism — supports the thesis. AAS abuse may be creating acquired fragile axes in genetically predisposed men.
Does Post-Cycle Therapy Work?
The PCT industry sells a comforting story: take clomiphene, tamoxifen, hCG, and your hormones will recover. The evidence is more nuanced.
For Short-Term Users: Possibly
İbis and colleagues (BJU Int, 2026) published the first comparative cohort study on PCT effectiveness. They followed 79 men with ≤6 months of AAS use and documented normal pre-cycle hormones:
| Outcome at 12 months | No Treatment | Clomiphene alone | Clomiphene + hCG |
|---|---|---|---|
| Normozoospermia | 58.6% | 69.2% | 87.5% |
| ≥20% testicular volume increase | 6.9% | — | 70.8% |
Clomiphene plus hCG independently predicted normozoospermia (OR 6.23) and motility recovery (OR 4.85). But note: hormonal recovery occurred by month 6 across all groups, including the untreated group. The main PCT benefit was accelerating fertility recovery, not hormonal recovery. Testosterone came back on its own.
For Long-Term Users: Probably Not
The CloTASH study (Henriksen and Havnes, 2024) — the first longitudinal clomiphene trial in long-term AAS users (mean 11 years of use) — painted a bleaker picture:
- Only 5 out of 10 reached normal testosterone range (9–30 nmol/L)
- HPG axis response varied enormously and didn't correlate with symptom severity
- 7 of 10 also received hCG — still poor response
Long-term users likely have irreversible Leydig cell damage and possibly durable KNDy neuron dysfunction that SERMs simply cannot overcome. The İbis data (short-term users) and CloTASH data (long-term users) together suggest a dose-response relationship: brief exposure allows recovery; prolonged exposure causes permanent damage.
The Black Market Danger
Even when men attempt PCT, they may not be taking what they think. Blazewicz and colleagues (Front Chem, 2025) analyzed 63 PCT drug samples seized from the Polish black market between 2020 and 2024:
- 34.9% did not contain the declared active ingredient
- 6.4% contained undeclared additional compounds
- The most commonly claimed PCT drugs were clomiphene (77%), tamoxifen (75%), and hCG (74%)
Men self-administering PCT are frequently taking nothing — or taking unknown substances. The entire recovery protocol many users rely on is built on products with no quality assurance.
Beyond Hormones: The Cardiovascular and Psychiatric Toll
PPAAH is not the only lasting consequence of AAS use. The damage extends to the heart and the mind.
Cardiovascular
A Danish national cohort study (Circulation, 2025) tracked 1,189 AAS users matched to 59,450 controls over a mean of 11 years:
- Substantially increased cardiovascular disease incidence
- 3× higher mortality — predominantly cardiac death and suicide
A forensic autopsy review (Front Cardiovasc Med, 2025) of 19 AAS-related deaths found left ventricular hypertrophy in 14 of 19 cases, myocardial fibrosis, and sudden cardiac death even without coronary artery disease. The mechanism: AAS-induced hypertrophy plus fibrosis creates a substrate for fatal arrhythmias.
Psychiatric
Data presented at ENDO 2025 revealed:
- 34% of current users and 22% of past users had psychiatric diagnoses, versus 5% of non-users
- Suicidal depression is the most life-threatening withdrawal complication
- The strongest predictor of severe withdrawal is psychiatric comorbidity, not hormonal levels
Researchers described an "underground, invisible epidemic of body image disorders and AAS use" — a population suffering in silence, rarely presenting to endocrinologists, and often concealing their use from physicians.
What This Means
The PPAAH framework changes how we should think about AAS-related hypogonadism in several ways:
1. Normal testosterone doesn't mean normal recovery. INSL3 reveals Leydig cell damage that persists years after cessation. A man whose testosterone reads 14 nmol/L may have half the Leydig cell capacity he should — leaving him vulnerable to premature age-related decline with no reserve to draw on.
2. The damage is dose-dependent and cumulative. Short-term users (≤6 months) have a reasonable chance of full recovery, especially with PCT for fertility parameters. Long-term users face a much grimmer prognosis. Every additional cycle degrades recovery potential.
3. Both the brain and the testes are damaged. PPAAH is not purely testicular (that would show elevated LH/FSH) or purely central (that wouldn't explain the INSL3 findings). It's both. The HPG axis sustains damage at multiple levels simultaneously.
4. Genetic vulnerability matters. Not everyone who uses AAS develops PPAAH. The fragile axis hypothesis — men with subclinical GnRH pathway variants — may explain who is most at risk. But we have no way to identify these men prospectively because the genetic testing doesn't exist in clinical practice.
5. PCT has limited value for the highest-risk group. The men who most need recovery assistance — long-term users with the most Leydig cell damage — are precisely the ones for whom PCT is least effective. SERMs can't regenerate Leydig cells that no longer exist.
The Diagnostic Gap
PPAAH highlights a fundamental problem in how we evaluate hormonal recovery after AAS use. The standard panel — total testosterone, LH, FSH — misses the key information. What clinicians should be measuring but almost never do:
- INSL3 — the only circulating biomarker that directly reflects Leydig cell number and maturation state
- Free testosterone (not just total) — because SHBG suppression creates a false sense of recovery
- hCG stimulation test — to assess testicular reserve capacity, not just resting output
Until INSL3 enters routine clinical practice, PPAAH will remain systematically underdiagnosed. Men will be told their hormones have recovered when their factories are running at half capacity.
A Note on Language
The term "abuse" in PPAAH is the authors' choice and reflects the clinical literature's framing. It's worth noting that many AAS users don't see their use as abuse — they see it as an informed choice about their own bodies. Whether one agrees with that framing doesn't change the biology. The HPG axis doesn't care about intent. It responds to pharmacology. And the pharmacology, in a dose-dependent and cumulative fashion, can cause lasting damage that no amount of post-cycle therapy can fully reverse.
The price of shortcuts is measured in Leydig cells — and unlike testosterone levels, Leydig cells don't bounce back.