International Urology and Nephrology

, Volume 44, Issue 3, pp 673–681 | Cite as

Calculated free testosterone and radioimmunoassay free testosterone as a predictor of subnormal levels of total testosterone

  • Graziele HalmenschlagerEmail author
  • Ernani Luis Rhoden
  • Charles Edison Riedner
Urology – Original Paper



To evaluate the relationship among aFT, cFT, and total testosterone (TT) and the best method in diagnosing subnormal levels of TT.


A total of 213 men were analyzed. Fasting blood samples were drawn for the determination of the lipid profile as well as of plasmatic glucose and serum levels of albumin, TT, aFT, and sex hormone-binding globulin (SHBG). The values of cFT were determined by Vermeulen’s formula.


No correlation between aFT and cFT was observed (r = 0.062; P = 0.368), except after controlling for confounders (r = 0.188; P = 0.007). Only 44.8% of hypogonadal men (TT ≤ 300 ng/dL) were classified by aFT, whereas 72.4% of hypogonadal men were classified by both TT and cFT. Sensitivity, specificity, positive and negative predictive values, and positive likelihood ratio were greater in cFT when compared with aFT.


Our results suggest that cFT is more accurate in diagnosing subnormal levels of TT. Furthermore, we do not recommend using aFT due to its lack of accuracy. Further studies should be performed in order to evaluate the correlation between aFT and cFT with clinical signs and symptoms of androgen deficiency.


Analog free testosterone Calculated free testosterone Androgen deficiency 



Halmenschlager is supported by Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorCAPES. We thank Federal University of Health Sciences of Porto Alegre (UFCSPA) for financial support.

Conflict of interest

The authors declare that they have no conflict of interest. This article is intended for publication in the Urology section.


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Copyright information

© Springer Science+Business Media, B.V. 2011

Authors and Affiliations

  • Graziele Halmenschlager
    • 1
    Email author
  • Ernani Luis Rhoden
    • 2
    • 3
  • Charles Edison Riedner
    • 4
  1. 1.Curso de Pós-Graduação em Ciências da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA)Porto AlegreBrazil
  2. 2.Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA)Porto AlegreBrazil
  3. 3.Médico do Hospital Moinhos de VentoPorto AlegreBrazil
  4. 4.Urology Unit of Militar Hospital of Porto AlegrePorto AlegreBrazil

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