hormone secretion and activity and is therefore used

as a surrogate marker for GH levels, and has been

validated as an accurate marker of GH levels over

time.

Studies have shown that GH and testosterone

levels are closely related and that boys with delayed

puberty and healthy older men with low-normal

testosterone and IGF-1 have increased serum GH

and IGF-1 levels with exogenous testosterone treat-

ment.

2,26

IGF-1/GH and testosterone also appear to

have similar clinical effects, with IGF-1/GH reversing

endothelial progenitor cell dysfunction and testo-

sterone increasing the number of endothelial pro-

genitor cells.

27,28

Thus, it is reasonable to expect that

low GH levels will correlate with sexual dysfunction,

and a link between GH levels and male sexual

dysfunction has been demonstrated.

20,29

This study

builds on the current literature and examines a relation-

ship between IGF-1 and validated measures of patient-

reported sexual function, namely the Sexual Health

Inventory for Men (SHIM) and the Expanded Prostate

Cancer Index Composite (EPIC) questionnaires.

30,31

Methods

Patient enrollment

The retrospective study protocol was approved by

the Institutional Review Board of Baylor College

of Medicine and 65 patients scheduled for radical

prostatectomy between July 2007 and June 2008

from the practice of MK and LIL were included in

the study. All subjects provided a preoperative blood

sample for serum IGF-1 and testosterone levels

between 1 week and 2 months before scheduled

prostatectomy, and all samples were analyzed in the

same laboratory (Baylor College of Medicine Depart-

ment of Nuclear Medicine) using enzyme-linked

immunosorbent assay in keeping with national

standards for reproducibility and accuracy. Subjects

were asked to complete the SHIM questionnaire as

well as the sexual function domain portion of the

EPIC questionnaires before prostatectomy. None of

the subjects included in the study were treated with

hormone ablation therapy for prostate cancer before

or after completion of the above questionnaires.

Statistical analysis

Statistical analysis of the data was performed using

Statistical Package for the Social Sciences (SPSS),

version 7.5, for Windows (Chicago, IL, USA) and

Stata IE Version 10 for Macintosh (College Station,

TX, USA). The distribution of data was determined

using histogram analysis. Multivariate analysis

was carried out using linear regression analysis.

Spearman’s correlation coefficients were calculated

and

-values

0.05 were considered statistically

significant.

Results

The median age of subjects included in the study

was 58 years (range, 46–77 years) (Table 1). Asso-

ciated comorbid conditions included hypertension

(41.5% of patients), hyperlipidemia (46.2%), vascu-

lopathy (4%), as defined by symptoms or objective

measurements of coronary artery disease, carotid

stenosis or peripheral vascular disease and diabetes

Table 1

Patient characteristics

Variable

% (x/n)

Median age, years (range)

58 (46–77)

Age

50 years

6.2 (4/65)

50–59 years

49.2 (32/65)

60–69 years

33.8 (22/65)

70 years

10.8 (7/65)

Race

White or Caucasian

85.2 (23/27)

Black

11.1 (3/27)

Hispanic

3.7 (1/27)

Comorbid conditions

Diabetes mellitus

13.8 ( 9/65)

Hypertension

41.5 (27/65)

Hyperlipidemia

46.2 (30/65)

Coronary artery disease

4.6 (3/65)

Depression

6.2 (4/65)

Social history

Cigarette smoking

Non-smoker

75.4 (49/65)

Previous history of smoking

21.5 (14/65)

Current smoker

3.1 (2/65)

Occasional to moderate alcohol

consumption

49.2 (32/65)

Sexual history

ED before RP

29.2 (19/65)

TRT before RP

3.1 (2/65)

Mean BMI,

(range)

27.6, 11 (20.0–37.8)

Prostate cancer Gleason grade

56.9 (33/58)

27.6 (16/58)

6.9 (4/58)

3.4 (2/58)

1.7 (1/58)

Hormone levels

Median total testosterone (ng dl

), s.d.

358.0

136.4

Median IGF-1 (mg dl

), s.d.

235.0

86.4

Questionnaire scores

Median SHIM score, s.d.

19.5

8.7

Median EPIC sexual score, s.d.

56.4

28.3

Median EPIC hormonal score, s.d.

10.0

1.5

Abbreviations: BMI, body mass index; ED, erectile dysfunction;

EPIC, Expanded Prostate Cancer Index Composite; IGF-1, insulin-

like growth factor 1; RP, radical prostatectomy; SHIM, Sexual

Health Inventory for Men; TRT, testosterone replacement therapy.

IGF-1 levels correlate with sexual dysfunction

AW Pastuszak

et al

221

International Journal of Impotence Research