| name | icsm-repeat-testosterone-low |
| description | Recommends repeating total testosterone measurement on at least two separate occasions when the initial result is below 12 nmol/L before starting testosterone therapy. Triggered when a clinician finds a low total testosterone (<12 nmol/L) and questions whether confirmation is needed prior to treatment. |
Repeat testosterone measurement if low before therapy
STEP 1 — Gather Information
Collect a morning (07:00–11:00) fasting total testosterone level using a reliable assay, and document symptoms suggestive of hypogonadism (e.g., low libido, erectile dysfunction, fatigue). Ensure the sample was not drawn during acute illness.
STEP 2 — Rule In / Rule Out
Is the initial total testosterone <12 nmol/L?
- Yes → Proceed to repeat testing.
- No → Consider other diagnoses; no repeat needed for testosterone deficiency confirmation.
STEP 3 — Classify or Stratify
Are both repeat total testosterone measurements (taken on separate days) <12 nmol/L?
- Yes → Confirm biochemical hypogonadism.
- No → Consider functional causes, assay variability, or transient suppression; repeat testing may be deferred.
STEP 4 — Decide
If hypogonadism is confirmed (≥2 low results), discuss testosterone therapy initiation after shared decision‑making.
If not confirmed, evaluate for reversible factors (obesity, opioids, illness) and consider lifestyle optimization before retesting.
Clinical Guardrails / Mimics / Pitfalls
Do not base therapy on a single low testosterone; avoid testing during acute illness or non‑fasting states; recognize that obesity, opioids, glucocorticoids, and acute illness can cause transient low total testosterone; ensure assay reliability and proper timing.
Concrete Clinical Example
A 48‑year‑man presents with decreased libido and morning fatigue. Initial fasting total testosterone is 10 nmol/L. Repeat measurements on two separate mornings yield 9 nmol/L and 11 nmol/L. Biochemical hypogonadism is confirmed, and testosterone therapy is discussed after evaluating symptoms and preferences.
Source: Male hypogonadism: recommendations from the Fifth International Consultation on Sexual Medicine (ICSM 2024), International Society for Sexual Medicine, 2025, https://doi.org/10.1093/sxmrev/qeaf036
