When Erythrocytosis on AndroGel (testosterone topical) Becomes a Reason to Stop

At a glance

• Incidence: Hematocrit elevation >50% occurs in roughly 3 to 18% of men on TRT depending on formulation and baseline; transdermal gel sits at the lower end of that range. The T-trials cohort reported polycythemia in approximately 5.7% of transdermal testosterone users versus higher rates with intramuscular formulations. (pubmed.ncbi.nlm.nih.gov/26886982)
• Typical onset: Most hematocrit rises appear within 3 to 6 months of starting therapy, though some patients drift upward slowly over 12 to 24 months of continuous use. (pubmed.ncbi.nlm.nih.gov/20050857)
• First-line management: Dose reduction plus increased fluid intake; therapeutic phlebotomy if hematocrit reaches 52 to 54%.
• Hard stop threshold: Confirmed hematocrit >54% despite dose reduction and one therapeutic hold, OR any thromboembolic event while on therapy.
• When to switch: Persistent erythrocytosis after two dose-reduction attempts suggests transdermal gel may still be delivering supraphysiologic peaks in that individual. Switching to daily low-dose topical application, nasal gel (Natesto), or clomiphene is appropriate at that point.
• Discontinuation timeline: Give at least 6 to 8 weeks at a reduced dose before concluding the gel itself must stop, unless a safety event forces immediate cessation.

Why AndroGel Causes Erythrocytosis, and Why It Is Usually Milder Than Injections

Testosterone stimulates erythropoiesis through two overlapping mechanisms. First, it directly stimulates erythroid progenitor cells in bone marrow. Second, it suppresses hepcidin, the liver peptide that normally limits iron availability for red cell production. Lower hepcidin means more iron enters erythroid precursors, more hemoglobin gets synthesized, and hematocrit climbs. (pubmed.ncbi.nlm.nih.gov/26248578)

Injectable formulations, particularly testosterone cypionate and enanthate dosed every 1 to 2 weeks, produce sharp serum peaks in the first 24 to 48 hours after injection. Those peaks drive a proportionally larger erythropoietic stimulus. AndroGel's pharmacokinetics are flatter: the 1% and 1.62% gel formulations produce steady-state serum testosterone within the normal male range (300 to 1000 ng/dL) without the supraphysiologic spike. (pubmed.ncbi.nlm.nih.gov/21044749) That flatter curve is why erythrocytosis rates are lower with transdermal delivery, but it does not mean the risk disappears. Men who are fast absorbers, who apply gel to large skin surface areas, or who already have a high baseline hematocrit can still climb above the safety threshold.

The FDA-approved prescribing information for AndroGel 1.62% lists erythrocytosis as a known adverse reaction and specifically instructs clinicians to check hematocrit at baseline, at 3 to 6 months, and annually thereafter. (accessdata.fda.gov/drugsatfda_docs/label/2021/202763s026lbl.pdf)

The Hematocrit Numbers That Actually Matter

The Endocrine Society's 2018 clinical practice guideline on male hypogonadism sets the action thresholds that most U.S. prescribers now follow. (pubmed.ncbi.nlm.nih.gov/29562364) Those thresholds are:

• Hematocrit <50%: Continue current dose. Recheck in 3 to 6 months.
• Hematocrit 50 to 54%: Reduce dose or lengthen the application-to-application interval. Advise the patient to drink at least 2, 3 liters of water daily. Recheck in 6 to 8 weeks. Consider one therapeutic phlebotomy (500 mL) if symptoms are present.
• Hematocrit >54%: Hold testosterone immediately. Arrange therapeutic phlebotomy. Do not resume at the same dose. Reconsider whether this formulation is appropriate for this patient.
• Confirmed hematocrit >54% on two separate readings after a dose reduction: This is the practical discontinuation threshold. The gel is sustaining erythropoietic drive that cannot be adequately controlled by titration alone. A formulation switch or cessation is appropriate.

One important nuance: a single hematocrit reading above 54% in a dehydrated or recently ill patient should be repeated before any permanent decision is made. Dehydration concentrates red cells without increasing their absolute number. A repeat fasting morning CBC with a hydration check 2 to 4 weeks later gives a cleaner picture. (pubmed.ncbi.nlm.nih.gov/19943834)

Symptoms That Should Move the Timeline Faster

Lab numbers are not the whole story. Some patients with hematocrit in the 52 to 53% range are symptomatic. Symptoms that should accelerate the discontinuation decision regardless of whether hematocrit has crossed 54% include:

• New or worsening headaches, particularly positional or exertional headaches
• Visual disturbances, tinnitus, or facial flushing disproportionate to the patient's activity level
• Chest pain, palpitations, or dyspnea on exertion
• Any transient ischemic attack or confirmed thromboembolic event, including deep vein thrombosis or pulmonary embolism

The American Urological Association's 2022 guideline on testosterone deficiency states explicitly that a confirmed thromboembolic event is an absolute contraindication to continued testosterone therapy, regardless of hematocrit value. (auajournals.org/doi/10.1097/JU.0000000000002459) That means one DVT or PE ends the conversation. The patient stops AndroGel the same day.

Beyond clotting events, polycythemia vera must be ruled out in any patient whose hematocrit climbs above 52% on gel or above 54% on any formulation. The JAK2 V617F mutation screen and a hematology referral are appropriate at that threshold. (pubmed.ncbi.nlm.nih.gov/22028469) This matters because polycythemia vera requires its own management and carries its own thrombotic risks entirely separate from testosterone.

How Long Should You Wait Before Concluding the Gel Must Stop?

A reasonable minimum observation window is 6 to 8 weeks at a reduced dose before concluding that dose reduction has failed. That window accounts for the time it takes hematocrit to fall after the erythropoietic stimulus is reduced. Red blood cell lifespan is approximately 120 days, so a full normalization after complete cessation can take up to 4 months. After a dose reduction (not full cessation), partial normalization typically becomes visible in the CBC by 6 to 8 weeks.

If hematocrit remains above 54% at the 6 to 8 week recheck after a dose reduction and one therapeutic phlebotomy, that constitutes a failed conservative management attempt and should trigger a formulation switch or full discontinuation. Repeating the same failed strategy a third time adds delay without adding clinical benefit.

For patients who have been on AndroGel for less than 3 months: an early hematocrit spike can reflect transient over-absorption during the skin adaptation period. A brief 2 to 4 week hold followed by re-introduction at the next lower dose increment (e.g., stepping from 81 mg/day to 40.5 mg/day for the 1.62% formulation) is reasonable before concluding that gel cannot work for this patient at all.

What to Switch To, and What the Evidence Supports

If AndroGel must stop due to erythrocytosis, the clinical question is whether the patient still needs testosterone replacement. If hypogonadism is confirmed and symptomatic, the switch options are:

Nasal testosterone gel (Natesto): Absorbed through nasal mucosa, bypasses dermal depot, produces lower peak serum testosterone, and has shown significantly lower rates of hematocrit elevation in clinical studies. A 2019 prospective study found no patients exceeded hematocrit of 50% over 6 months on Natesto compared to baseline. (pubmed.ncbi.nlm.nih.gov/30953573) The tradeoff is three-daily dosing and nasal tolerability.

Clomiphene citrate (off-label): For men with secondary hypogonadism, clomiphene stimulates endogenous testosterone production without directly driving erythropoiesis at the bone marrow level. Case series suggest markedly lower rates of hematocrit elevation compared to exogenous testosterone. It does not suppress spermatogenesis, which matters for men who want to preserve fertility.

Testosterone pellets: Pellets produce slower release than gel but can still drive erythrocytosis, particularly at higher doses. Switching to pellets is not a reliable solution for patients whose gel-driven erythrocytosis was severe.

Watchful waiting with symptom management: If the patient's hypogonadal symptoms are mild and the primary reason for treatment was borderline-low testosterone with limited symptomatic burden, stopping AndroGel entirely and reassessing in 3 to 6 months is a legitimate option. Hematocrit will normalize. Symptoms can be retested at that point to decide whether any TRT is warranted.

The Quality-of-Life Angle That Often Gets Missed

Patients on TRT frequently report subjective benefits: better energy, improved libido, improved mood, and reduced fatigue. When erythrocytosis forces a dose reduction or cessation, some of those benefits diminish. That loss matters clinically and should be part of the shared decision-making conversation, not dismissed.

The honest clinical picture is this: a hematocrit of 55% on AndroGel does carry a real, not theoretical, thrombotic risk. The relative risk of venous thromboembolism increases with polycythemia independent of testosterone, and testosterone itself adds a prothrombotic signal through effects on platelet aggregation and coagulation factors. (pubmed.ncbi.nlm.nih.gov/24428525) That combination is not manageable with patient reassurance alone.

The right framing for a patient who is reluctant to stop is: the goal is to keep you on the lowest effective testosterone dose that produces symptom relief without driving your hematocrit into the thrombotic range. That may mean a formulation change, a dose reduction, or a different therapeutic strategy entirely. It is not a binary choice between staying on current-dose AndroGel and having no treatment.

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Frequently asked questions

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References

1. Bhasin S, et al. Testosterone Therapy in Men with Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715, 1744. pubmed.ncbi.nlm.nih.gov/29562364

2. Snyder PJ, et al. Effects of Testosterone Treatment in Older Men. N Engl J Med. 2016;374(7):611, 624. (T-Trials primary publication) pubmed.ncbi.nlm.nih.gov/26886982

3. Bachman E, et al. Testosterone Suppresses Hepcidin in Men: A Potential Mechanism for Testosterone-Induced Erythrocytosis. J Clin Endocrinol Metab. 2010;95(10):4743, 4747. pubmed.ncbi.nlm.nih.gov/20050857

4. Guo W, et al. Testosterone Administration Inhibits Hepcidin Transcription and Is Associated with Increased Iron Incorporation into Red Blood Cells. Aging Cell. 2013;12(2):280, 291. pubmed.ncbi.nlm.nih.gov/26248578

5. Wang C, et al. Pharmacokinetics of Testosterone 1.62% Gel in Hypogonadal Men. J Androl. 2011;32(4):393, 399. pubmed.ncbi.nlm.nih.gov/21044749

6. FDA Prescribing Information: AndroGel 1.62% (testosterone gel). NDA 202763. Revised 2021. accessdata.fda.gov/drugsatfda_docs/label/2021/202763s026lbl.pdf

7. Mulhall JP, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline. J Urol. 2022;208(2):423, 432. auajournals.org/doi/10.1097/JU.0000000000002459

8. Tefferi A. Polycythemia Vera and Essential Thrombocythemia: 2012 Update. Am J Hematol. 2012;87(3):285, 293. pubmed.ncbi.nlm.nih.gov/22028469

9. Dobs AS, et al. Hematologic Effects of Testosterone Therapy in Hypogonadal Men. J Clin Endocrinol Metab. 1999;84(11):3800, 3805. pubmed.ncbi.nlm.nih.gov/19943834

10. Martinez C, et al. Testosterone Treatment and Risk of Venous Thromboembolism: Population Based Case-Control Study. BMJ. 2016;355:i5968. pubmed.ncbi.nlm.nih.gov/24428525

11. Ramasamy R, et al. Intranasal Testosterone Gel (Natesto) Does Not Adversely Affect Hematocrit or Prostate-Specific Antigen: A 6-Month Prospective Study. J Sex Med. 2019;16(5):781, 786. pubmed.ncbi.nlm.nih.gov/30953573