Clinical Hypogonadism and Androgen Replacement Therapy: An Overview

Dana A. Ohl; Susanne A. Quallich

Disclosures

Urol Nurs. 2006;26(4):253-259,269. 

In This Article

Laboratory Evaluation

The most practical laboratory test in the diagnosis of hypogonadism is the serum testosterone level. There are controversies concerning which levels are most relevant. The various assays that can be used include total testosterone, bioavailable testosterone, and free testosterone.

Many argue that free testosterone or bioavailable testosterone levels give the best information about a man's androgen status. These tests give an accurate picture of the amount of testosterone available for biological effects, negating problems associated with variations in SHBG. Disadvantages of these tests include the difficulty in achieving accurate results due to differing methods of assays, and the increased cost of obtaining these more complicated tests. Arguments for utilizing total testosterone levels include lower cost, and practitioners in favor of this method argue that there are very few conditions where SHBG levels are abnormal enough to cause a clinically significant change in the level of bioavailable testosterone. The laboratory tests should be drawn between 8:00 am and 11:00 am, due to the circadian rhythm of testosterone secretion. Laboratory standards are defined by morning blood draws.

Additional testing may include gonadotropin levels, and these tests can help in determining whether the individual's hypogonadism is primary (low testosterone, with elevated LH) or secondary (low testosterone with normal or low LH). Men with an inappropriate gonad otropin response to a low testosterone should be evaluated for pituitary pathology, possibly including pituitary gland imaging studies. A serum prolactin level may be obtained to assure hyperprolactinemia is not the etiology of the hypogonadism. If the patient is obese, a baseline estradiol level can be of value. Some authors (Morales et al., 2000) suggest that measurement of the SHBG level can be helpful as part of the initial workup. However, the value of this measurement is less well-defined in planning treatment, as SHBG levels are influenced by both hormonal and nonhormonal factors (Vermeulen, 2001). Bone densitometry may be considered in those men at high risk for osteoporosis.

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