Testosterone Deficiency (Male Hypogonadism)
Testosterone deficiency is over-diagnosed and over-treated, so the guideline is strict about how you make the diagnosis: it requires both low levels AND symptoms, confirmed on two early-morning measurements — not a single low number in a man who feels fine.
The big picture
Testosterone deficiency is over-diagnosed and over-treated, so the guideline is strict about how you make the diagnosis: it requires both low levels AND symptoms, confirmed on two early-morning measurements — not a single low number in a man who feels fine. Before treating, you must consider fertility (testosterone is contraceptive) and counsel risks. The discipline of diagnosis is the high-yield point.
The framework: diagnose properly (symptoms + two morning levels, ~300 ng/dL cutoff) → work out the cause (primary vs secondary) → consider fertility → treat and monitor (hematocrit, symptoms, PSA).
Mechanism pathway
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Diagnostic algorithm
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Board traps
Diagnosis needs BOTH symptoms AND low T on two early-morning measurements (~300 ng/dL cutoff) — not one low number.
Check LH/FSH to separate primary (high) from secondary (low/normal) hypogonadism.
Never give exogenous testosterone to a man who wants fertility — it's a contraceptive; use hCG/clomiphene/gonadotropins.
Monitor hematocrit (polycythaemia) and PSA on therapy.
Treat the symptoms, not just the number.