Testosterone gel contamination has been suspected as a cause for higher testosterone concentrations observed in capillary (fingerstick) relative to venipuncture specimens in some patients . Target serum testosterone concentration ranges for TRT or GAHT are a matter of debate, but society guidelines commonly promote the goal of serum testosterone concentrations within the male physiologic range, which is approximately between 400 and 700 ng/dl or 13.9–24.3 nmol/L , , . The diagnosis of hypogonadism is made in men with clinical symptoms and signs of testosterone deficiency (e.g., fatigue, low libido, loss of body hair, loss of muscle mass, erectile dysfunction) plus persistently low serum total testosterone and/or free testosterone concentrations 11,12. Ideally, serum testosterone concentrations should be measured at least 8 h since last application of the gel. Additionally, patients receiving testosterone by injection attained desired physical changes faster than patients in testosterone therapy with topical gel formulations.
This assay has an AMR of 1.0–2000 ng/dL (0.03–69.4 nmol/L), CRR up to 10,000 ng/dL (347 nmol/L; with dilution), and total imprecision less than 6.0 % . In older men, the diurnal pattern is blunted, along with an observed rate of testosterone concentration decline of around 1 %–2 % annually . The main goals of testosterone therapy in this population are to reduce gender dysphoria and promote desired masculinization such as increased muscle mass, deepened voice, and male pattern hair growth. This difference between arms could not be reproduced when applying gel distal to the venipuncture site. In 10 volunteers we compared T/E ratios between gel-exposed and unexposed arms where the gel was applied on the venipuncture site or distal of the venipuncture site.
The testosterone dose was reduced to 25 mg daily, but the patient then reported worsening of sexual symptoms despite adhering to this therapy. His physician emphasized the importance of medication adherence and advised against applying testosterone gel within 8 h before any blood draw. Thus, the high testosterone value was registered in the patient's records as ‘‘erroneously elevated due to contamination of the sample with testosterone from patient's skin’’. The patient denied any symptoms or adverse effects attributable to testosterone excess and stated he had not been on any other testosterone medications or over-the-counter supplements of any kind. "All other testosterone medications" includes testosterone pellets, oral formulation, subcutaneous injection, or unknown (a small number of medication lists for patients documented testosterone but without specifying formulation). The analytical measurement range (AMR) and clinical reportable range (CRR) are 12–1500 ng/dL (0.4–52.1 nmol/L). We did not have data on fasting status or the exact timing of serum measurement relative to last dose of testosterone.
Testosterone is a vital hormone that supports male characteristics and overall health. If you rub the gel in yourself, then make sure to wash your hands immediately afterwards.4 However, be sure to follow the steps discussed below to ensure you are doing everything you can to reduce the risk. The study also discovered that using a t-shirt could effectively reduce the risk of transfer by almost 50%.9 If post-application measures are not taken, adverse effects may occur.7 It’s important to remain cautious and take the necessary measures to reduce the risk. Again, if someone were to come into contact with the area of skin exposed to testosterone, then it may transfer onto another individual.4
Overall, we present 7 cases where contamination of the phlebotomy site by testosterone gel was strongly suspected to have caused spuriously high serum testosterone concentrations. Their study showed that 62 transgender men receiving GAHT with transdermal testosterone (patch or topical gel) had significantly lower median concentrations of serum total testosterone (326 ng/dL) when compared with those receiving injectable preparations (525 ng/dL). We think it is likely that testosterone gel contamination was the underlying cause for at least some of the 41 remaining subjects who had one or more serum testosterone concentrations of 1000 ng/dL or higher.
‍TRT gels can noticeably improve your quality of life, but a common concern is the risk of secondary transfer.6 They have minimal side effects, with the most commonly reported being itchy, irritated skin around the area the gel was applied.3 If you have low testosterone and symptoms (also known as hypogonadism), your doctor may prescribe you testosterone replacement therapy (TRT).1
Another study demonstrated that patients prescribed injectable testosterone therapy had higher serum testosterone concentrations at the beginning of treatment compared to patients prescribed topical gel, with stable serum testosterone concentrations over time . We compared overall distribution of total testosterone serum concentrations among patients who were prescribed testosterone by intramuscular injection, topical gel, or transdermal patch or not prescribed testosterone at all (Fig. 2). Documentation in the electronic health record revealed 7 patients where contamination of the phlebotomy site by topical gel was strongly supported as the cause of supraphysiologic testosterone serum concentrations. The present study shows that supraphysiological testosterone serum concentrations from topical gel testosterone contamination is a factor that can affect multiple patients, particularly at centers that frequently prescribe testosterone topical gel. To try to identify possible cases of testosterone topical gel contamination, we focused chart review on those prescribed topical gel who had at least one serum total testosterone concentration exceeding 1000 ng/dL, the range described in previous case reports of testosterone gel contamination of phlebotomy sites 20,21.
In the retrospective timeframe, there was a total of 19,623 unique patients with 40,979 total serum testosterone measurements. Testosterone topical gels generally show less variability in serum concentrations compared to transdermal patch . Testosterone concentrations in patients receiving intramuscular testosterone ester injections are influenced by timing of blood sample relative to last injection, with peak concentrations between 2 and 4 days after injection and a total duration of action of approximately 2 weeks. However, there is debate on the requirement for a fasting specimen, as some studies have not shown a significant impact of fasting status on serum testosterone concentrations . When monitoring testosterone therapy, it is important to recognize that a variety of factors (e.g., age, genetic polymorphisms, drug-drug interactions, medication adherence or misuse, contamination of sample, fasting status) can influence measured serum testosterone concentration. Overall, we present 7 cases of spuriously high testosterone concentrations strongly suspected to be due to venipuncture performed near or at the location of prior testosterone gel application.