"Testosterone total LC‑MS/MS" means total testosterone measured by liquid chromatography–tandem mass spectrometry. LC‑MS/MS separates and precisely quantifies testosterone with high specificity and sensitivity, reducing cross‑reactivity and false results seen with many immunoassays. It is the reference method for diagnosing low or high testosterone, assessing replacement therapy, and monitoring treatment, especially when accurate low‑level measurement is needed.

A high total testosterone (measured by mass spectrometry) means your circulating testosterone is above the lab reference range. Causes include testosterone therapy or steroid use, androgen-secreting tumors (testicular or adrenal), PCOS in women, or other endocrine disorders. Symptoms can be acne, hair changes, menstrual irregularity or infertility. Repeat morning tests, check free testosterone, SHBG and pituitary hormones, and see an endocrinologist.

The testosterone assay is a morning blood test measuring total testosterone in serum, usually collected between 7–10 AM. Common lab methods include automated immunoassays (chemiluminescent) and the more accurate gold-standard liquid chromatography–tandem mass spectrometry (LC-MS/MS). Free testosterone can be measured by equilibrium dialysis or calculated from SHBG and albumin. Two morning samples are often recommended for confirmation.

LC‑MS/MS stands for liquid chromatography–tandem mass spectrometry. It’s a laboratory technique that first separates compounds (liquid chromatography) then measures their mass and fragmentation patterns (tandem mass spectrometry). It’s highly sensitive and specific, commonly used to confirm and quantify drugs and metabolites at very low concentrations, reducing false positives and providing reliable forensic or clinical toxicology results.

A good total testosterone depends on sex and age. For adult men, typical desirable levels are roughly 300–1000 ng/dL (10–35 nmol/L). For adult women, normal total testosterone is much lower, about 15–70 ng/dL (0.5–2.4 nmol/L). Reference ranges vary by lab and age; levels are best measured in the morning and interpreted with symptoms by a clinician.

High reverse T3 (rT3) measured by LC‑MS/MS—an accurate lab method—means increased levels of the inactive T3 metabolite. It suggests reduced conversion of T4 to active T3, often seen with acute or chronic illness, stress, fasting, certain medications, or high cortisol. Isolated high rT3 needs correlation with TSH, free T4/T3 and symptoms; discuss results with your clinician.