Clinical Chemistry 63:8 1326–1330 (2017)
Clinical Case Study
Hypogonadism with Normal Serum Testosterone Ingrid Borovickova,1* Naomi Adelson,1 Ananth Viswanath,2 and Rousseau Gama1
CASE DESCRIPTION A 69-year-old man was referred to the endocrine clinic with a 3-year history of erectile dysfunction, reduced libido, and lack of nocturnal tumescence with no response to phosphodiesterase type 5 inhibitors (sildenafil and tadalafil). The symptoms troubled him to such an extent that he asked his general practitioner to be referred to a specialist clinic. The patient had been through a normal puberty. Although he fathered no children, he was unconcerned about this and never sought fertility investigation or treatment. His past medical history was clinically significant for newly diagnosed interstitial lung disease owing to hypersensitivity pneumonitis, osteoarthritis, and gastroesophageal reflux; his only medications were ibuprofen gel and lansoprazole. He was never prescribed steroids, ketoconazole, or spironolactone. He had not undergone ionizing radiation and denied using over-thecounter or recreational drugs. He was an ex-smoker who drank 8 units of alcohol weekly. He did not recall a prior history of mumps or testicular trauma. He was unaware of any family members who had an autoimmune disorder or fertility issues. On examination he was 178 cm tall and obese [body mass index (BMI) 37.3 kg/m2]. His arm-span-to-height ratio was ⬍1.05 and his cardiovascular examination did not reveal heart murmurs. He had a normal hair pattern and no gynecomastia. Testicular volume was reduced bilaterally at 12–15 mL (reference interval ⱖ15 mL). Testosterone, measured by a 1-step chemiluminescent immunoassay (Abbott Architect, second generation testosterone assay) was 16.0 nmol/L (reference interval 4.9 –32 nmol/L); his sex hormone– binding globulin (SHBG)3 was increased at 153 nmol/L (13.5–71.4 nmol/L) as were luteinizing hormone (LH) and folliclestimulating hormone (FSH) at 33.4 IU/L (0.6 –12.0
Departments of 1 Biochemistry and 2 Endocrinology, New Cross Hospital, The Royal Wolverhampton NHS Trust, Wolverhampton, UK. * Address correspondence to this author at: Biochemistry Department, New Cross Hospital, The Royal Wolverhampton NHS Trust, Tallaght Dublin 24, Ireland. Fax +353-014143931; e-mail:
[email protected]. Received August 23, 2016; accepted October 26, 2016. DOI: 10.1373/clinchem.2016.265124 © 2016 American Association for Clinical Chemistry 3 Nonstandard abbreviations: SHBG, sex hormone–binding globulin; LH, luteinizing hormone; FSH, follicle-stimulating hormone; bioT, bioavailable testosterone; FT, free testosterone; LOH, late-onset hypogonadism.
1326
QUESTIONS TO CONSIDER 1. What are the criteria for LOH? 2. What are the pitfalls of measuring serum total testosterone concentration? 3. What common conditions cause increased SHBG? 4. What methods should be used to determine FT and bioT?
IU/L) and 54.7 IU/L (1.0 –11.9 IU/L), respectively (Table 1). These results, which indicated hypergonadotropic hypogonadism, were confirmed on repeated testing 3 weeks later. At that time, testosterone was also measured by LC-MS/MS and the results confirmed a normal total testosterone, thus excluding a positive immunoassay interference. Low calculated values of bioavailable testosterone (bioT) [2.05 nmol/L (2.29 –14.5 nmol/L)] and free testosterone (FT) [0.106 nmol/L (0.174 – 0.729 nmol/L)] were consistent with hypogonadism. Further blood tests showed normal results for the routine metabolic panel, complete blood count, transferrin saturation, estrogen, thyroid tests, and prolactin. Plasma glucose, adjusted calcium, vitamin B12, and morning cortisol results were also unremarkable, making an autoimmune condition unlikely. After discussion with the patient, transdermal testosterone replacement was initiated. At follow-up 3 months later, his total testosterone had increased to 39 nmol/L; this was mirrored by a reduction in SHBG (73 nmol/L) and gonadotropins (FSH 16.0 IU/L, LH 8.9 IU/L). His libido, general well-being, and erectile function improved substantially. The etiology of his hypergonadotropic hypogonadism could not be further elucidated because of unexpectedly rapid progression of his interstitial lung disease leading to oxygen dependency. He declined further investigations and eventually stopped taking testosterone replacement upon learning of a poor prognosis of his rapidly progressing lung disease. DISCUSSION Male hypogonadism, which results from failure of the testes to produce adequate testosterone and spermatozoa, is caused by disruption of the hypothalamic–pituitary– gonadal axis (1 ). Serum testosterone measurement is rec-
Clinical Case Study
Table 1. Relevant patient results.a Standard international units
US customary units
Patient results Reference interval
Baseline
Testosterone (4.9–32 nmol/L)
a
3 Months
Reference interval
Baseline
39
Testosterone (141–922 ng/dL)
BioT (2.29–14.5 nmol/L)
2.05
12.1
BioT (66–417 ng/dL)
FT (0.174–0.729 nmol/L)
0.106
0.6
SHBG (13.5–71.4 nmol/L)
16
Patient results
153
FSH (1.0–11.9 IU/L)
54.7
LH (0.6–12 IU/L)
33.4
Albumin (35–55 g/L)
37
3 Months
461
1124
59
349
FT (5–21 ng/dL)
3.05
73
SHBG (13.5–71.4 nmol/L)
16
FSH (1.0–11.9 mIU/mL)
54.7
LH (0.6–12 mIU/mL)
33.4
8.9
3.7
3.9
8.9 39
153
17.3
Albumin (3.5–5.5 g/dL)
73 16
Follow-up testosterone, SHBG, LH, and FSH were measured while the patient was on testosterone treatment 3 months after the presentation.
ommended if features of hypogonadism are present, including reduced libido, erectile dysfunction, small testicles, gynecomastia, hot flushes, loss of body hair, infertility, reduced bone density, and loss of muscle strength, and should also be considered in those individuals with reduced energy, low mood, sleep disturbance, mild anemia, and diminished physical performance (1 ). Hypogonadism may be hypergonadotropic (primary testicular failure with loss of feedback inhibition leading to increased LH and FSH) or hypogonadotropic (hypothalamic–pituitary disease causing absolute or relative gonadotropin deficiency). Some conditions may act
at both sites. These are often chronic, multisystem diseases, including iron overload, chronic renal failure, diabetes mellitus, or age-related changes in male gonadal function (2 ). Failure of descent of the testes into the scrotum is a cause of hypergonadotropic hypogonadism, which is attributed to the raised temperature within the abdominal cavity. A similar mechanism has been noted in varicoceles (2 ). Acquired hypergonadotropic hypogonadism may arise from testicular torsion or iatrogenic castration in the management of prostate or testicular cancer. Inflammatory and autoimmune disorders (Table 2) should be excluded by appropriate history and investigations.
Table 2. Etiology of male hypergonadotropic hypogonadism. Testicular damage
Testicular trauma Injury
Genetic and developmental
Chromosomal Klinefelter (47 XXY)
Drugs
Alcohol Drugs interfering with androgen synthesis
Surgical complications
47XXY/46 XY mosaicism
Aminoglutethimide
Torsion
XX/X0 (mixed gonadal dysgenesis)
Etomidate
XYY syndrome
Ketoconazole
Y chromosome microdeletions
Steroids
Infection/inflammation Mumps orchitis HIV Granulomatous conditions
Noonan syndrome Developmental
Drugs blocking action at the androgen receptor Spironolactone
Lepromatous leprosy
Maldescended testes
Cyproterone acetate
Autoimmune conditions
Congenital anorchia
Flutamide
Polyglandular syndrome Cancer Testicular cancer Ionizing radiation
Testicular agenesis Androgen synthesis problems 46 XY disorders of sexual development
Alkylating agents (damaging to seminiferous tubules) Cyclophosphamide Busulphan Chlorambucil
Clinical Chemistry 63:8 (2017) 1327
Clinical Case Study Men experience an age-related decline in circulating testosterone concentration commencing in early adult life and continuing into old age. This decline is associated with reduced testicular reserve and diminished hypothalamo-pituitary drive. This leads to late-onset hypogonadism (LOH). The exact relationships between falling circulating hormones and age-related symptoms, morbidity, and health outcomes are unclear. It is recognized that older men with conditions such as obesity, type 2 diabetes, chronic obstructive pulmonary disease, inflammatory disease, liver disease, or cardiac or renal failure have a higher prevalence of borderline low serum testosterone. These associations are stronger than the effects of aging alone on testosterone. Symptoms of hypogonadism in older individuals lack clinical specificity because they overlap with normal aging. Diagnosis of LOH therefore requires clinical features of androgen deficiency, consistently low testosterone concentration (on at least 2 occasions) (1 ), and the exclusion of other causes of hypogonadism. The prevalence of LOH is low—the European Male Ageing Study reported a prevalence of 2.1% in men over the age of 40 years (3 ). The key measurement in assessment of male hypogonadism is serum testosterone. The variability in performance in testosterone assays makes it impossible to set a universal diagnostic testosterone cutoff for male hypogonadism. Automated immunoassays are subject to interferences that can be overcome by the use of mass spectrometry– based technologies. Serum testosterone is affected by the circadian rhythm, which may exceed 30% difference between the peak morning values (before 10 AM) and those obtained later in the day (2 ). Acute illness may cause a transient testosterone decrease. Borderline testosterone results, therefore, must be repeated in the morning and upon recovery and performed with a reliable assay. There are no specific recommendations regarding the type of assay or time frame requirement for repeat testing. In healthy men, approximately 44% of the circulating testosterone is specifically bound to SHBG, 54% is nonspecifically bound to albumin, and 2% is unbound or free (4 ). SHBG binding makes hormone unavailable for diffusion into cells, so the physiologically relevant components of total testosterone are the non–SHBG-bound fractions. Abnormal SHBG may indicate that the FT is lower or higher than would have been expected from the total testosterone, potentially leading to under- or overdiagnosis of hypogonadism in situations with higher SHBG or lower SHBG, respectively. SHBG is higher in older individuals and in patients with hyperthyroidism, liver cirrhosis, HIV, malnutrition, or caloric restriction (anorexia nervosa), or those using anticonvulsants or estrogen-containing medications. A genetic variant, Asp327-⬎Asn, affecting 10%– 1328
Clinical Chemistry 63:8 (2017)
POINTS TO REMEMBER • Diagnosis of male LOH requires clinical features of androgen deficiency, consistently low testosterone concentration, and exclusion of classical causes of hypogonadism. • Interpretation of serum total testosterone is affected by many factors, including circadian rhythm, acute illness, age, adiposity, variations in analytical techniques, and SHBG concentration. SHBG should always be measured along with total serum testosterone. • Assessment of gonadotropins (LH, FSH) is helpful for determining the cause of established gonadal failure because their increase is usually clear cut. • Reliance on total serum testosterone can lead to over- or underdiagnosis of hypogonadism in men with abnormal SHBG concentrations. When total testosterone is near the lower limit of the reference interval or SHBG is outside the reference interval, FT or bioT may aid the diagnosis. • Analytical methods are established for direct measurement of bioT and FT but these are time-consuming and may be inaccurate. Algorithms to calculate bioT and FT are assay dependent and not simply transferable to other assays without careful revalidation.
20% of the population, results in increased SHBG glycosylation associated with reduced clearance and increased serum concentration (2 ). Low SHBG is found in obesity, hypothyroidism, type 2 diabetes/insulin resistance, nephrotic syndrome, acromegaly, and treatment with steroids or progestins (1, 2, 5 ). Our patient’s increased SHBG could have been attributable to age, longstanding hypogonadism, or a genetic variant. When total testosterone concentration is borderline and/or when variations in SHBG concentrations are expected, serum FT (non-SHBG–non–albumin-bound testosterone) and nonspecifically bound bioT (free ⫹ albumin-bound testosterone) reflect the clinical situation more accurately. FT and bioT are well correlated and usually interchangeable (6 ). BioT can be measured with the ammonium sulfate precipitation technique. The gold standard for FT is the equilibrium dialysis method, although a mass spectrometry– based assessment of FT in ultrafiltrates has been proposed as a candidate comparison method (7 ). These techniques are time-consuming and not commonly available. Immunoassay involving an analog ligand has been found to correlate poorly with equilibrium dialysis and has substantial problems with accuracy (6, 7 ). FT and bioT may also be calculated by use of one of several published algorithms. The 2 most widely used equations for calculating bioT and FT are those described
Clinical Case Study by Vermeulen et al. (6 ) and Sodergard et al. (4 ). These calculations depend on the concentrations of total testosterone, SHBG, albumin, and the constants for the binding of testosterone to SHBG and albumin. These equations have been shown to correlate well with equilibrium dialysis FT, but care must be taken because various values for the binding constants have been reported with various methods. Three other algorithms based on the concentrations measured with a gold standard technique in large numbers of samples have been recently proposed for estimating FT and bioT (8, 9 ). FT and bioT in all 3 equations, however, were significantly associated with SHBG concentrations, which is particularly undesirable in older men in whom accurate estimations of FT and bioT are needed to support a clinical diagnosis of hypogonadism. The results of FT and bioT depend on the total testosterone and SHBG results, which differ considerably for commercially available assays, and these algorithms are assay dependent and not transferrable to other assays. Testosterone supplementation for LOH remains controversial. Longer-term studies of sufficient power to document clinical outcomes are lacking and there are unresolved concerns about cardiovascular side effects and the potential for an occult prostate cancer to become a clinical cancer. Testosterone replacement has been shown to improve all domains of sexual function even in older men with reduced libido and testosterone concentration (10 ) but the risks and benefits must be carefully weighed.
Author Contributions: All authors confirmed they have contributed to
the intellectual content of this paper and have met the following 3 requirements: (a) significant contributions to the conception and design, acquisition of data, or analysis and interpretation of data; (b) drafting or revising the article for intellectual content; and (c) final approval of the published article. Authors’ Disclosures or Potential Conflicts of Interest: No authors declared any potential conflicts of interest.
References 1. Bhasin S, Cunningham GR, Hayes FJ, Matsumoto AM, Snyder PJ, Swerdloff RS, Montori VM. Testosterone therapy in adult men with androgen deficiency syndromes: an Endocrine Society clinical practice guideline. J of Clin Endocrinol Metab 2010;95: 2536 –59. 2. Belchetz PE, Barth JH, Kaufman JM. Biochemical endocrinology of the hypogonadal male. Ann Clin Biochem 2010;47:503–15. 3. Wu FCW, Tajar A, Beynon JM, Pye SR, Silman AJ, Finn JD, et al. Identification of late-onset hypogonadism in middle aged and elderly men. N Engl J Med 2010;363: 123–35. 4. Sodergard R, Backstrom T, Shanbhag V, Carstensen H. Calculation of free and bound fractions of testosterone and estradiol-17 to human plasma proteins at body temperature. J Steroid Biochem 1982;16:801–10. 5. Vermeulen A, Kaufman JM, Giagulli VA. Influence of some biological indexes on sex hormone-binding globulin and androgen levels in aging or obese males. J Clin Endocrinol Metab 1996;81:1821– 6. 6. Vermeulen A, Verdonck L, Kaufman JM. A critical evaluation of simple methods for the estimation of free testosterone in serum. J Clin Endocrinol Metab 1999;84: 3666 –72. 7. Van Uytfanghe K, Stockl D, Kaufman JM, Fiers T, De Leenheer A, Thienpont LM. Validation of 5 routine assays for serum free testosterone with a candidate reference measurement procedure based on ultrafiltration and isotope dilution–gas chromatography–mass spectrometry. Clin Biochem 2005;38:253– 61. 8. Emadi-Konjin P, Bain J, Bromberg IL. Evaluation of an algorithm for calculation of serum “bioavailable” testosterone (BAT). Clin Biochem 2003;36:591– 6. 9. International Society for the Study of the Aging Male. Free & bioavailable testosterone calculator. http://www.issam.ch/freetesto.htm (Accessed May 2017). 10. Cunningham GR, Stephens-Shields AJ, Rosen RC, Wang C, Bhasin S, Matsumoto AM, et al. Testosterone treatment and sexual function in older men with low testosterone levels. J Clin Endocrinol Metab 2016;101:3096 –104.
Commentary Kiang-Teck Jerry Yeo*
This case illustrates the importance of correlating pertinent laboratory results to the patient’s clinical presentation in the assessment of male hypogonadism. Because the common symptoms associated with hypogonadism (e.g., low libido, erectile dysfunction, decreased vitality, depressed mood) are nonspecific, serum testosterone determination is important in the workup and diagnosis of
Department of Pathology, The University of Chicago, Chicago, IL. * Address correspondence to the author at: Department of Pathology, The University of Chicago, 5841 S Maryland Ave., Chicago, IL 60615. Fax 603-702-6268; e-mail
[email protected]. Received January 9, 2017; accepted January 31, 2017. DOI: 10.1373/clinchem.2016.269472 © 2017 American Association for Clinical Chemistry
hypogonadism. However, there is not a consensus diagnostic cutoff for serum testosterone for male hypogonadism. Various professional societies recommend lower reference limits for adult men ranging from 200 to 300 ng/dL (6.9 – 10.4 nmol/L). This patient showed classic symptoms of hypogonadism, yet a baseline serum total testosterone was well within the reference interval. The authors point out important factors that must be considered for an apparently “discordant” testosterone value, including sampling time to potential immunoassay interferences. However, taken in conjunction with increased LH and FSH concentrations, and the finding of an increased SHBG concentration (typical of older men), this patient’s calculated FT and bioT indicated that the bioactive fraction of testosClinical Chemistry 63:8 (2017) 1329
