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GnRH Stimulation Test

Indication:

In case of delayed or premature puberty. Further diagnostic workup in hypogonadotropic hypogonadism: the GnRH test distinguishes between hypothalamic (tertiary) or hypophyseal (secondary) hypogonadism.

Test method:

Measurement of LH and FSH in serum before administration of 100 μg GnRH i.v. (for children 60 μg per m² BSA, maximum 100 μg GnRH), after 30 min LH and FSH are measured again.

Normal values in puberty:

Basal LH <2 U/l, FSH <2 U/l, after stimulation LH rises >5 U/l, FSH rises too but to a smaller extent compared to LH. The extent of LH surge correlates with maturity during puberty.

Interpretation in hypogonadotropic hypogonadism:

LH should increase to 2–4 fold, FSH to 1.5–2 fold. The regular increase excludes a pituitary cause and suggests a hypothalamic disease (Kallmann syndrome).

Interpretation in precocious puberty:

Low basal concentrations of LH and FSH without a significant increase after stimulation suggest peripheral hormone production (especially gonadotropin-independent tumors). Central precocious puberty is characterized by elevated basal gonadotropins, which increase disproportionately after stimulation.

Prolactin test

Index

PSA test

Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

References

Guder, W. G. & Nolte, J. Das Laborbuch für Klinik und Praxis
Urban + Fischer, 2009

Köhn, F.-M. (2004). [diagnosis and therapy of hypogonadism in adult males].
Urologe A, 43(12):1563-81; quiz 1582–3.

Trottmann, M., Dickmann, M., Stief, C. G., and Becker, A. J. (2010). [laboratory workup of testosterone].
Urologe A, 49(1):11–15.

Deutsche Version: GnRH Stimulationstest