When is bioavailable testosterone a redundant test in the diagnosis of hypogonadism in men?
OBJECTIVE
Total testosterone (TT) is frequently prescribed with an SHBG and/or free or bioavailable testosterone measurement. Our objective was to identify a TT range for which subsequent SHBG measurement/calculation adds no additional clinical information.


METHODS
Study data were composed of 3955 sets of TT, SHBG and calculated bioavailable testosterone (cBAT) results from unscreened ambulatory male subjects, aged 18-99.


RESULTS
90% of mismatches between TT and cBAT were observed with TT levels between 6.5 and 13.0 nmol/L, with only slight age variation and no important change with albumin level. SHBG measurement restricted to male patients with TT between 6.5 and 13.0 nmol/L should enable reagent cost savings of over 55%.


CONCLUSIONS
We suggest that a TT level below 6.5 nmol/L or above 13.0 nmol/L provides sufficient useful information for ruling out hypogonadism in ambulatory adult males. This strategy of BAT testing should lead to significant time and cost savings.
Gheorghiu
Ionela
I
Collaborative Research for Effective Diagnostics (CRED), Centre Hospitalier Universitaire de Sherbrooke, 3001 13e Avenue Nord, Sherbrooke, Quebec, Canada J1H 5N4.
Moshyk
Andriy
A
Lepage
Raymond
R
Ahnadi
Charaf E
CE
Grant
Andrew M
AM
D000293:Adolescent; D000328:Adult; D000368:Aged; D000418:Albumins; D001682:Biological Availability; D003955:Diagnostic Tests, Routine / Q000191:economics / Q000379:methods* / Q000592:standards; D006801:Humans; D007006:Hypogonadism / Q000175:diagnosis* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013739:Testosterone / Q000032:analysis / Q000378:metabolism*
D000418:Albumins; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone