return to T index  

return to index page

PTD - 298

Test Directory -  Testosterone

Synonyms

Total testosterone

Clinical Indications

In females, testosterone is produced in the ovaries and adrenal glands and is primarily measured to exclude androgen excess as a result of adrenal or ovarian tumours. In males, testosterone is usually measured as a part of the investigation of impotence/infertility or suspected hypopituitarism.

Request Form 

Combined Pathology Blood form (Yellow/Black or Blue for GP's)

Availability

On request. 

Specific Criteria

Assessment of androgen status.

Patient Preparation

Samples should ideally be collected early morning between 7 and 10 am in males. Patients should be fasting.

Turnaround Time

Same Day

Specimen

Serum

Volume

0.5 ml

Container

Yellow top (SST) tube or

Paediatric orange top (lithium-heparin)

Causes for Rejection

Unlabelled sample

Reference Ranges

 

Testosterone (nmol/L)

Age

Males

Females

< 6 months

Less than 6.0

<0.2

6 months - 1 yr

< 0.2

<0.2

1 - 5 years

< 0.9

< 0.4

5 - 7 years

< 1.0

< 0.4

7 - 8 years

See table below

< 0.4

8 - 18 years

See table below

18 - 49 years

8.6 - 29.0

0.3 - 1.7

> 49 years

6.7 - 25.7

0.1 - 1.4

 

 

Testosterone (nmol/L)

Tanner Stage

Males (aged 7-18 yrs)

Females (aged 8-18 yrs)

1

Less than 0.09

< 0.21

2

< 15.0

< 0.36

3

2.3 - 27.0

< 0.82

4

6.2 - 26.5

< 0.93

5

6.5 - 30.6

0.16 - 1.33

Reference: Roche method insert.

Interpretation

 

Female: Studies show that a total testosterone less than 5.0 nmol/L is rarely associated with serious pathology. Levels above 5.0 nmol/L may indicate a serious ovarian or adrenal disorder, but are also seen in some cases of PCOS. In such cases, raised androstenedione and raised DHEA-S suggest adrenal involvement, whereas increased androstenedione and normal DHEA-S suggest ovarian pathology.

Male: Please note diurnal rhythm: levels are highest at 711am and lowest around 6.00pm. Levels decrease with age (due to decrease in SHBG) and some normal men will have levels at the lower end of the reference range. Eating may transiently lower testosterone levels.  If a patient has a low result the test should be repeated on a 9 a.m. fasting sample. Patients with testicular failure will have low testosterone levels with raised LH and FSH levels.

Testosterone levels may be low in erectile dysfunction BUT do not correlate with erectile dysfunction (or impotence / libido) i.e. may have normal levels.

Lab Handling

Processing: Analysed from primary tube and stored at 4C in the cold room (CB23)

top


Version 1.1 / July 2015                                                                                                          Approved by: Consultant Biochemist