The ratio of serum prolactin to testosterone can help in the evaluation of a male with hypogonadism and mild hyperprolactinemia. It can aid the decision to perform MRI of the pituitary. The authors are from the Cleveland Clinic.
Patient selection: male with hypogonadism and mild hyperprolactinemia
Outcome: pituitary abnormality seen on MRI
Parameters:
(1) serum prolactin in ng/mL
(2) serum testosterone in ng/dL (presumably total testosterone)
(3) serum LH in mU/mL
(4) serum FSH in mU/mL
prolactin to testosterone ratio =
= (serum prolactin in ng/mL) / (serum testosterone in ng/dL)
LH to FSH ratio =
= (serum LH) / (serum FSH)
If prolactin is significantly elevated (> 50 ng/mL), then a pituitary abnormality should be suspected.
Panels for evaluating a patient with a mild elevation in serum prolactin (15-50 ng/mL):
|
PRL/Test ratio
|
Prolactin
|
Percent Abnormal MRI
|
|
>= 0.10
|
NA
|
47% (order MRI)
|
|
< 0.10
|
< 25 ng/mL
|
8% (do not order MRI)
|
|
< 0.10
|
> 25 ng/mL
|
19% (order MRI)
|
The above is the approach used in Figure 3.
|
PRL/Test ratio
|
LH
|
Percent Abnormal MRI
|
|
>= 0.10
|
NA
|
47%
|
|
< 0.10
|
LH < 5 mU/mL
|
21%
|
|
< 0.10
|
>= 5 mU/mL
|
5%
|
|
PRL/Test ratio
|
LH/FSH Ratio
|
Percent Abnormal MRI
|
|
>= 0.10
|
NA
|
46%
|
|
< 0.10
|
< 0.8
|
29%
|
|
< 0.10
|
>= 0.8
|
4%
|
Performance:
• The area under the ROC curve is 0.75.
