The Increase of Leukocytes as a New Putative Marker of Low-Grade Chronic Inflammation and Early Cardiovascular Risk in Polycystic Ovary Synd
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《临床内分泌与代谢杂志》
Abstract
White blood cell (WBC) count is a known risk factor for atherosclerotic vascular disease in adult women. Polycystic ovary syndrome (PCOS) is potentially a risk factor for atherosclerosis and cardiovascular disease. The aim of the present study was to investigate leukocyte count in PCOS. One hundred and fifty PCOS women matched for age and body mass index with 150 healthy women were enrolled. WBC count, C-reactive protein, and a complete anthropometrical, metabolic, and hormonal evaluation were performed in both groups. Serum insulin, glucose level, and lipid profile were also measured in each subject. WBC count was significantly higher (P < 0.0001) in PCOS with (interquartile range in parentheses) 7260 (393) cells/mm3, compared with controls with 5220 (210) cells/mm3. C-reactive protein levels were significantly increased (P < 0.0001) in PCOS with 2 (1) mg/liter compared with healthy women with 0.7 (0.8) mg/liter. In both groups, there was a significant (P < 0.0001) linear correlation between WBC count and homeostasis model assessment score (PCOS, r = 0.94; controls, r = 0.91). Multiple linear regression analysis showed that other hormone levels are not predictors of leukocyte count both in PCOS and control women. In conclusion, our data demonstrate that PCOS women have an increased WBC count that correlates with homeostasis model assessment values.
POLYCYSTIC OVARY SYNDROME (PCOS) is a common endocrine-metabolic disorder associated with long-term health risks, including diabetes mellitus (1, 2, 3, 4) and coronary artery disease (5, 6). In particular, insulin resistance, hyperandrogenemia, and dyslipidemia are likely to be the major risk factors for the occurrence of cardiovascular disease in PCOS (6, 7).
Inflammation is now thought to play a key role in the pathophysiological mechanism of atherosclerosis (7, 8) and cardiovascular disease (9). Several markers of inflammation, such as C-reactive protein (CRP), IL-6, soluble intercellular adhesion molecule type 1, and white blood cell (WBC) count, are found to be significant predictors of the risk of coronary heart disease (10) and future cardiovascular events (10). In particular, an elevated WBC count is a risk factor for atherosclerotic vascular disease (11) and is present in adult women with genetic predisposition to type 2 diabetes (12). Inflammation may also be associated with the metabolic syndrome (13, 14) and a raised WBC count (14). Therefore the association of leukocyte count with cardiovascular risk factors may represent a manifestation of subclinical disease, or alternatively leukocyte count could be part of a chain leading to atherosclerosis (15).
Recently, low-grade chronic inflammation has been linked to the insulin-resistance syndrome (16), and it was reported that women with PCOS have significantly increased CRP concentrations (13). The present study was performed to investigate the relationship between leukocyte count and hormonal-metabolic features in women with PCOS.
Subjects and Methods
The procedures used were in accordance with the guidelines of the Helsinki Declaration on human experimentation. The study was approved by the Institutional Review Board of the University of Naples, Italy. The purpose of the protocol was explained both to the patients and control women, and written consent was obtained at the beginning of the study.
Subjects
One hundred and fifty women with PCOS were enrolled in this study. The diagnosis of PCOS was made according to the National Institutes of Health criteria (17). One hundred and fifty women were enrolled and considered as the control group. PCOS and control groups were matched for age and body mass index (BMI). The controls were defined as age and BMI matched with PCOS cases when the differences between the cases and controls were less than 2 yr and 1 kg/m2 for age and BMI, respectively. The subjects were selected in Naples (Department of Endocrinology) and in Catanzaro (Department of Obstetrics and Gynecology). Specifically, 78% of the PCOS were enrolled in Naples, and 100% of controls were enrolled in Catanzaro. To match adequately the cases and the controls, we screened 354 healthy women who attended a cervical cancer prevention clinic (University of Catanzaro) for a routine Pap test. The healthy state of the women in the control group was determined by medical history, physical and pelvic examination, and complete blood chemistry. Their normal ovulatory state was confirmed by transvaginal ultrasonography (TV-USG) and plasma progesterone (P) assay. Both procedures were performed during the luteal phase of the menstrual cycle (7 d before the expected menses). The presence of fluid in the cul-de-sac at TV-USG and a plasma P assay greater than 31.8 nmol/liter (>10 ng/ml, metric units) were considered criteria for ovulation having occurred (18).
For all subjects, exclusion criteria included pregnancy, hypothyroidism, hyperprolactinemia, Cushing’s syndrome, congenital adrenal hyperplasia, and current or previous (within the last 6 months) use of oral contraceptives, glucocorticoids, antiandrogens, ovulation induction agents, antidiabetic and antiobesity drugs, or other hormonal drugs. None of the patients were affected by neoplastic, metabolic, or cardiovascular disorder or other concurrent medical illness (including diabetes or kidney, liver, thyroid, autoimmune, cerebrovascular, and ischemic heart disease). All subjects were nonsmokers and had normal glucose tolerance (19) and normal physical activity, and none drank alcoholic beverages. Moreover, acute and chronic inflammation was excluded on the basis of medical history, physical examination, and routine laboratory tests, including measurement of oral temperature, WBC count, and urinalysis. In each woman, weight and height were measured to calculate the BMI. The waist/hip ratio (WHR) was also calculated as previously described (20).
Protocol
At study entry, all subjects underwent venous blood samples for complete hormonal assays, WBC count, lipid profile, oral glucose tolerance test, and measurement of insulin values. All blood samples were obtained in the morning between 0800 and 0900 h after an overnight fast and resting in bed during the early follicular phase (d 2–5) of a spontaneous or P-induced menstrual cycle.
During the same visit, all subjects underwent TV-USG and anthropometric measurements, including BMI and WHR.
Biochemical and hormonal analysis
Basal blood samples were obtained to evaluate complete hormonal assays. The following hormonal serum levels were measured: LH, FSH, 17?-estradiol E2, 17-hydroxyprogesterone (17-OHP), testosterone (T), androstenedione (A), dehydroepiandrosterone sulfate (DHEAS), prolactin (PRL), and sex-hormone-binding globulin (SHBG). All blood samples for each woman were assayed in duplicate and immediately centrifuged, and the serum was then stored at –80 C until analysis.
In each woman, the free androgen index and the homeostasis model assessment (HOMA) score were calculated as previously described (20).
Leukocyte count was determined within 2 h after venipuncture with an automatic workstation cell counter, Technicon H3 (Bayer Diagnostics, Munich, Germany). The instrument was calibrated with the Setpoint hematology calibrator (Bayer Diagnostics) with mean values for each parameter of five replicates counted. The calibration obtained was successfully verified with Testpoint hematology control normal (Bayer Diagnostics) and with three levels of Emacheck quality hematology reference controls (Hematronix, Concord, CA): low abnormal level, normal level, and high abnormal level. The coefficient of variation (CV) determined on five replicates of each control ranged from 0.9–1.0% for leukocyte parameters. CRP was measured by latex immunoturbidometric methodology on an automated clinical analyzer system, Synchron CX4 (Beckman Diagnostics, Fullerton CA). The lower detection limit was 2 mg/liter, and the intraassay CV was 5%.
Plasma glucose levels were determined by the glucose oxidase method on a Beckman glucose analyzer (Fullerton, CA). Plasma PRL, LH, FSH, E2, P, T, A, and DHEAS were all measured by specific RIA, as previously described (21, 22). The mean of two hormonal results was calculated. Serum 17-OHP levels were determined using a RIA (Diagnostic Systems Laboratories 5000, Webster, TX) with a sensitivity of 0.5 nmol/liter and an intra- and interassay CV of 8.9 and 9.0%, respectively. SHBG levels were measured using an immunoradiometric assay (Radim, Pomezia, Rome, Italy) with a sensitivity of 2.5 nmol/liter and an intra- and interassay CV, respectively, of 5.1 and 5.2%. Serum insulin was measured by a solid-phase chemiluminescent enzyme immunoassay using commercially available kits (Immunolite Diagnostic Products Co., Los Angeles, CA). The intra- and interassay CVs were less than 5.5%.
Statistical analysis
The Kolmogorov-Smirnov statistic with a Lilliefors significance level was used for testing normality. Because of the non-Gaussian distribution of the variables, the differences between continuous variables of the two groups were analyzed using the Mann-Whitney U test. Bivariate correlations were performed calculating the Spearman coefficient. In addition, simple and multiple regression analysis was performed to determine which variables predicted WBC or CRP. In assessing the suitability of the data for a linear regression model, the collinearity diagnostics were evaluated. Data are presented as median and interquartile range, and P < 0.05 was considered statistically significant. All analyses were run using SPSS 12.0.1 (SPSS Inc., Chicago, IL).
Results
The demographic, hormonal, and biochemical data of the PCOS and control groups are reported in Table 1.
In the PCOS group, LH, 17-OHP, T, A, E2, DHEAS, SHBG, serum insulin, and insulin sensitivity (HOMA index) were significantly different in comparison with control women. The leukocyte count was significantly higher in PCOS women compared with the control group, even though no case of leukocytosis was found in either group. Analyzing the leukocyte formula, we observed a significant (P < 0.0001) increase of lymphocytes and monocytes in PCOS women vs. controls. Also, CRP levels were significantly increased in PCOS compared with the controls.
In both groups, there was a significant association between leukocyte count and HOMA index (PCOS, r = 0.94 with P < 0.0001; controls, r = 0.91 with P < 0.0001).
Simple linear regression analysis showed that for the entire population the measure of HOMA was useful to predict WBC count as expected (linear regression coefficient ? = 0.97; P < 0.0001). A multiple linear regression analysis was performed by adding to the previous model a second independent variable (PCOS status no/yes = 0/1). In this model, predictors of WBC were HOMA (? = 0.35; P < 0.0001) and PCOS status (? = 0.66; P < 0.0001). Moreover, simple linear regression analysis showed that for the entire population, the measure of HOMA was useful to predict CRP levels (? = 0.68; P < 0.0001). A multiple linear regression analysis was performed by adding to the previous model a second independent variable (PCOS status no/yes = 0/1). The predictor of CRP levels was PCOS status (? = 0.62; P < 0.0001) and not HOMA (? = 0.10; P = 0.43). Finally, multiple linear regression analysis showed that other hormone levels are not predictors of leukocyte count both in PCOS and control women.
Discussion
To the best of our knowledge, this is the first study in the literature to demonstrate an increased leukocyte count in PCOS. The results of this study show that insulin resistance is probably the main factor responsible for the increase of leukocytes in patients with PCOS.
Multiple regression analysis did not demonstrate that hormone levels are predictors of leukocyte count both in PCOS and control women, suggesting that leukocyte increase is not affected by elevated circulating concentrations of T, A, DHEAS, LH, 17-OHP, or E2. In comparison with matched controls, PCOS women had greater serum insulin concentration and HOMA index, confirming previous data (2). In our study, leukocyte count significantly correlates with either fasting insulin concentrations or estimates of insulin sensitivity, suggesting that increased insulin production affects perhaps WBC count. Furthermore, a significant linear correlation between WBC count and HOMA index, both in PCOS and controls, could explain the increase of leukocyte count in subjects with lower insulin sensitivity. A large body of evidence shows a correlative and causative relationship between inflammation and insulin resistance (23, 24) and a linear correlation between HOMA index and WBC count (12, 25, 26). Indeed, inflammation has been recognized to play a central role in both initiation and progression of the atherosclerotic process (7); therefore, elevated leukocyte count is directly associated with increased incidence of coronary heart disease, ischemic stroke, and mortality from cardiovascular disease in African-American and white men and women (9). In agreement with Kelly et al. (13), we also found increased CRP concentrations in women with PCOS, hence suggesting CRP as a predictor of cardiovascular events and independently related to insulin insensitivity (16). In fact, Festa et al. (16) reported, in a larger study, the relationship between CRP, fibrinogen, WBC count, and components of insulin resistance in a nondiabetic population. The association of leukocyte count with cardiovascular risk factors could be a manifestation of subclinical disease.
In conclusion, we suggest that women with PCOS appear to show higher levels of leukocyte count, a marker of low-grade inflammation and cardiovascular risk, than age- and BMI-matched controls.
Acknowledgments
We are indebted to Ms. Laura Carbonaro for editing the text.
Footnotes
First Published Online October 13, 2004
Abbreviations: A, Androstenedione; BMI, body mass index; CRP, C-reactive protein; DHEAS, dehydroepiandrosterone sulfate; E2, 17?-estradiol; HOMA, homeostasis model assessment; 17-OHP, 17-hydroxyprogesterone; P, progesterone; PCOS, polycystic ovary syndrome; PRL, prolactin; T, testosterone; TV-USG, transvaginal ultrasonography; WBC, white blood cell; WHR, waist/hip ratio.
Received April 2, 2004.
Accepted October 5, 2004.
References
Ovalle F, Azziz R 2002 Insulin resistance, polycystic ovary syndrome, and type 2 diabetes mellitus. Fertil Steril 77:1095–1105
Dunaif A 1997 Insulin resistance and the polycystic ovary syndrome: mechanism and implications for pathogenesis. Endocr Rev 18:774–800
Legro RS, Kunselman AR, Dodson WC, Dunaif A 1999 Prevalence and predictors of risk for type 2 diabetes mellitus and impaired glucose tolerance in polycystic ovary syndrome: a prospective, controlled study in 254 affected women. J Clin Endocrinol Metab 84:165–169
Arslanian SA, Lewy VD, Danadian K 2001 Glucose intolerance in obese adolescents with polycystic ovary syndrome and ?-cell dysfunction and risk of cardiovascular disease. J Clin Endocrinol Metab 86:66–71
Talbott E, Guzick D, Clerici A, Berga S, Detre K, Weimer K, Kuller L 1995 Coronary heart disease risk factors in women with polycystic ovary syndrome. Arterioscler Thromb Vasc Biol 15:821–826
Conway GS, Agrawal R, Betteridge DJ, Jacobs HS 1992 Risk factors for coronary artery disease in lean and obese women with the polycystic ovary syndrome. Clin Endocrinol 37:119–125
Alexander RW 1994 Inflammation and coronary artery disease. N Engl J Med 331:468–469
Wilson PW, Kannel WB, Silbershatz H, D’Agostino RB 1999 Clustering of metabolic factors and coronary heart disease. Arch Intern Med 159:1104–1109
Lee CD, Folsom AR, Nieto FJ, Chambless LE, Shahar E, Wolfe DA 2001 White blood cell count and incidence of coronary hart disease and ischemic stroke and mortality from cardiovascular disease in African-American and white men and women. Am J Epidemiol 154:758–764
Hoffman M, Blum A, Baruch R, Kaplan E, Benjamin M 2004 Leukocytes and coronary heart disease. Atherosclerosis 172:1–6
Hasegawa T, Negishi T, Deguchi M 2002 WBC count, atherosclerosis and coronary risk factors. J Atheroscler Thromb 9:219–223
Pannacciulli N, Giorgino F, Martina RA, Resta O, Giorgino R, De Pergola G 2003 Effect of family history of type 2 diabetes on white blood cell count in adult women. Obes Res 11:1232–1237
Kelly CC, Lyall H, Petrie JR, Gould GW, Connell JM, Sattar N 2001 Low grade chronic inflammation in women with polycystic ovarian syndrome. J Clin Endocrinol Metab 86:2453–2455
Ford ES 2003 The metabolic syndrome and C-reactive protein, fibrinogen, and leukocyte count: findings from the Third National Health and Nutrition Examination Survey. Atherosclerosis 168:351–358
Nieto FJ, Szklo M, Folsom AR, Rock R, Mercuri M 1992 Leukocyte count correlates in middle-aged adults: the Atherosclerosis Risk in Communities (ARIC) Study. Am J Epidemiol 136:525–537
Festa A, D’Agostino Jr R, Howard G, Mykkanen L, Tracy RP, Haffner SM 2000 Chronic subclinical inflammation as part of the insulin resistance syndrome: the Insulin Resistance Atherosclerosis Study (IRAS). Circulation 102:42–47
Zawdaki JK, Dunaif A 1992 Diagnostic criteria for polycystic ovary syndrome: towards a rational approach. In: Dunaif A, Given JR, Haseltine F, Merriam GR, eds. Polycystic ovary syndrome. Boston: Blackwell; 377–384
Barbieri RL 1999 Infertility. In: Yen SSC, Yaffe RB, Barbieri RL, eds. Reproductive endocrinology: physiology, pathophisiology, and clinical management. 4th ed. Philadelphia: WB Saunders; 562–593
Gabir MM, Hanson RL, Dabelea D, Imperatore G, Roumain J, Bennett PH, Knowler WC 2000 The 1997 American Diabetes Association and 1999 World Health Organization criteria for hyperglycemia in the diagnosis and prediction of diabetes. Diabetes Care 23:1108–1112
Orio Jr F, Lucidi P, Palomba S, Tauchmanovà L, Cascella T, Russo T, Zullo F, Colao A, Lombardi G, De Feo P 2003 Circulating ghrelin concentrations in the polycystic ovary syndrome. J Clin Endocrinol Metab 88:942–945
Orio Jr F, Palomba S, Colao A, Tenuta M, Dentico C, Petretta M, Lombardi G, Nappi C, Orio F 2001 Growth hormone secretion after baclofen administration in different phases of the menstrual cycle in healthy women. Horm Res 55:131–136
Orio Jr F, Milan G, Palomba S, Cascella T, Tauchmanovà L, Savastano S, Zullo F, Lombardi G, Colao A, Vettor R 2003 Adiponectin levels in women with polycystic ovary syndrome. J Clin Endocrinol Metab 88:2619–2623
Xu H, Barnes GT, Yang Q, Tan G, Yang D, Chou CJ, Sole J, Nichols A, Ross JS, Tartaglia LA, Chen H 2003 Chronic inflammation in fat plays a crucial role in the development of obesity-related insulin resistance. J Clin Invest 112:1821–1830
Bloomgarden ZT 2003 Inflammation and insulin resistance. Diabetes Care 26:1922–1926
Choi KM, Lee J, Lee KW, Seo JA, Oh JH, Kim SG, Kim NH, Choi DS, Baik SH 2004 Comparison of serum concentrations of C-reactive protein, TNF-, and interleukin 6 between elderly Korean women with normal and impaired glucose tolerance. Diabetes Res Clin Pract 64:99–106
Temelkova-Kurktschiev T, Siegert G, Bergmann S, Henkel E, Koehler C, Jaross W, Hanefeld M 2002 Subclinical inflammation is strongly related to insulin resistance but not to impaired insulin secretion in a high risk population for diabetes. Metabolism 51:743–749(Francesco Orio, Jr., Stef)
White blood cell (WBC) count is a known risk factor for atherosclerotic vascular disease in adult women. Polycystic ovary syndrome (PCOS) is potentially a risk factor for atherosclerosis and cardiovascular disease. The aim of the present study was to investigate leukocyte count in PCOS. One hundred and fifty PCOS women matched for age and body mass index with 150 healthy women were enrolled. WBC count, C-reactive protein, and a complete anthropometrical, metabolic, and hormonal evaluation were performed in both groups. Serum insulin, glucose level, and lipid profile were also measured in each subject. WBC count was significantly higher (P < 0.0001) in PCOS with (interquartile range in parentheses) 7260 (393) cells/mm3, compared with controls with 5220 (210) cells/mm3. C-reactive protein levels were significantly increased (P < 0.0001) in PCOS with 2 (1) mg/liter compared with healthy women with 0.7 (0.8) mg/liter. In both groups, there was a significant (P < 0.0001) linear correlation between WBC count and homeostasis model assessment score (PCOS, r = 0.94; controls, r = 0.91). Multiple linear regression analysis showed that other hormone levels are not predictors of leukocyte count both in PCOS and control women. In conclusion, our data demonstrate that PCOS women have an increased WBC count that correlates with homeostasis model assessment values.
POLYCYSTIC OVARY SYNDROME (PCOS) is a common endocrine-metabolic disorder associated with long-term health risks, including diabetes mellitus (1, 2, 3, 4) and coronary artery disease (5, 6). In particular, insulin resistance, hyperandrogenemia, and dyslipidemia are likely to be the major risk factors for the occurrence of cardiovascular disease in PCOS (6, 7).
Inflammation is now thought to play a key role in the pathophysiological mechanism of atherosclerosis (7, 8) and cardiovascular disease (9). Several markers of inflammation, such as C-reactive protein (CRP), IL-6, soluble intercellular adhesion molecule type 1, and white blood cell (WBC) count, are found to be significant predictors of the risk of coronary heart disease (10) and future cardiovascular events (10). In particular, an elevated WBC count is a risk factor for atherosclerotic vascular disease (11) and is present in adult women with genetic predisposition to type 2 diabetes (12). Inflammation may also be associated with the metabolic syndrome (13, 14) and a raised WBC count (14). Therefore the association of leukocyte count with cardiovascular risk factors may represent a manifestation of subclinical disease, or alternatively leukocyte count could be part of a chain leading to atherosclerosis (15).
Recently, low-grade chronic inflammation has been linked to the insulin-resistance syndrome (16), and it was reported that women with PCOS have significantly increased CRP concentrations (13). The present study was performed to investigate the relationship between leukocyte count and hormonal-metabolic features in women with PCOS.
Subjects and Methods
The procedures used were in accordance with the guidelines of the Helsinki Declaration on human experimentation. The study was approved by the Institutional Review Board of the University of Naples, Italy. The purpose of the protocol was explained both to the patients and control women, and written consent was obtained at the beginning of the study.
Subjects
One hundred and fifty women with PCOS were enrolled in this study. The diagnosis of PCOS was made according to the National Institutes of Health criteria (17). One hundred and fifty women were enrolled and considered as the control group. PCOS and control groups were matched for age and body mass index (BMI). The controls were defined as age and BMI matched with PCOS cases when the differences between the cases and controls were less than 2 yr and 1 kg/m2 for age and BMI, respectively. The subjects were selected in Naples (Department of Endocrinology) and in Catanzaro (Department of Obstetrics and Gynecology). Specifically, 78% of the PCOS were enrolled in Naples, and 100% of controls were enrolled in Catanzaro. To match adequately the cases and the controls, we screened 354 healthy women who attended a cervical cancer prevention clinic (University of Catanzaro) for a routine Pap test. The healthy state of the women in the control group was determined by medical history, physical and pelvic examination, and complete blood chemistry. Their normal ovulatory state was confirmed by transvaginal ultrasonography (TV-USG) and plasma progesterone (P) assay. Both procedures were performed during the luteal phase of the menstrual cycle (7 d before the expected menses). The presence of fluid in the cul-de-sac at TV-USG and a plasma P assay greater than 31.8 nmol/liter (>10 ng/ml, metric units) were considered criteria for ovulation having occurred (18).
For all subjects, exclusion criteria included pregnancy, hypothyroidism, hyperprolactinemia, Cushing’s syndrome, congenital adrenal hyperplasia, and current or previous (within the last 6 months) use of oral contraceptives, glucocorticoids, antiandrogens, ovulation induction agents, antidiabetic and antiobesity drugs, or other hormonal drugs. None of the patients were affected by neoplastic, metabolic, or cardiovascular disorder or other concurrent medical illness (including diabetes or kidney, liver, thyroid, autoimmune, cerebrovascular, and ischemic heart disease). All subjects were nonsmokers and had normal glucose tolerance (19) and normal physical activity, and none drank alcoholic beverages. Moreover, acute and chronic inflammation was excluded on the basis of medical history, physical examination, and routine laboratory tests, including measurement of oral temperature, WBC count, and urinalysis. In each woman, weight and height were measured to calculate the BMI. The waist/hip ratio (WHR) was also calculated as previously described (20).
Protocol
At study entry, all subjects underwent venous blood samples for complete hormonal assays, WBC count, lipid profile, oral glucose tolerance test, and measurement of insulin values. All blood samples were obtained in the morning between 0800 and 0900 h after an overnight fast and resting in bed during the early follicular phase (d 2–5) of a spontaneous or P-induced menstrual cycle.
During the same visit, all subjects underwent TV-USG and anthropometric measurements, including BMI and WHR.
Biochemical and hormonal analysis
Basal blood samples were obtained to evaluate complete hormonal assays. The following hormonal serum levels were measured: LH, FSH, 17?-estradiol E2, 17-hydroxyprogesterone (17-OHP), testosterone (T), androstenedione (A), dehydroepiandrosterone sulfate (DHEAS), prolactin (PRL), and sex-hormone-binding globulin (SHBG). All blood samples for each woman were assayed in duplicate and immediately centrifuged, and the serum was then stored at –80 C until analysis.
In each woman, the free androgen index and the homeostasis model assessment (HOMA) score were calculated as previously described (20).
Leukocyte count was determined within 2 h after venipuncture with an automatic workstation cell counter, Technicon H3 (Bayer Diagnostics, Munich, Germany). The instrument was calibrated with the Setpoint hematology calibrator (Bayer Diagnostics) with mean values for each parameter of five replicates counted. The calibration obtained was successfully verified with Testpoint hematology control normal (Bayer Diagnostics) and with three levels of Emacheck quality hematology reference controls (Hematronix, Concord, CA): low abnormal level, normal level, and high abnormal level. The coefficient of variation (CV) determined on five replicates of each control ranged from 0.9–1.0% for leukocyte parameters. CRP was measured by latex immunoturbidometric methodology on an automated clinical analyzer system, Synchron CX4 (Beckman Diagnostics, Fullerton CA). The lower detection limit was 2 mg/liter, and the intraassay CV was 5%.
Plasma glucose levels were determined by the glucose oxidase method on a Beckman glucose analyzer (Fullerton, CA). Plasma PRL, LH, FSH, E2, P, T, A, and DHEAS were all measured by specific RIA, as previously described (21, 22). The mean of two hormonal results was calculated. Serum 17-OHP levels were determined using a RIA (Diagnostic Systems Laboratories 5000, Webster, TX) with a sensitivity of 0.5 nmol/liter and an intra- and interassay CV of 8.9 and 9.0%, respectively. SHBG levels were measured using an immunoradiometric assay (Radim, Pomezia, Rome, Italy) with a sensitivity of 2.5 nmol/liter and an intra- and interassay CV, respectively, of 5.1 and 5.2%. Serum insulin was measured by a solid-phase chemiluminescent enzyme immunoassay using commercially available kits (Immunolite Diagnostic Products Co., Los Angeles, CA). The intra- and interassay CVs were less than 5.5%.
Statistical analysis
The Kolmogorov-Smirnov statistic with a Lilliefors significance level was used for testing normality. Because of the non-Gaussian distribution of the variables, the differences between continuous variables of the two groups were analyzed using the Mann-Whitney U test. Bivariate correlations were performed calculating the Spearman coefficient. In addition, simple and multiple regression analysis was performed to determine which variables predicted WBC or CRP. In assessing the suitability of the data for a linear regression model, the collinearity diagnostics were evaluated. Data are presented as median and interquartile range, and P < 0.05 was considered statistically significant. All analyses were run using SPSS 12.0.1 (SPSS Inc., Chicago, IL).
Results
The demographic, hormonal, and biochemical data of the PCOS and control groups are reported in Table 1.
In the PCOS group, LH, 17-OHP, T, A, E2, DHEAS, SHBG, serum insulin, and insulin sensitivity (HOMA index) were significantly different in comparison with control women. The leukocyte count was significantly higher in PCOS women compared with the control group, even though no case of leukocytosis was found in either group. Analyzing the leukocyte formula, we observed a significant (P < 0.0001) increase of lymphocytes and monocytes in PCOS women vs. controls. Also, CRP levels were significantly increased in PCOS compared with the controls.
In both groups, there was a significant association between leukocyte count and HOMA index (PCOS, r = 0.94 with P < 0.0001; controls, r = 0.91 with P < 0.0001).
Simple linear regression analysis showed that for the entire population the measure of HOMA was useful to predict WBC count as expected (linear regression coefficient ? = 0.97; P < 0.0001). A multiple linear regression analysis was performed by adding to the previous model a second independent variable (PCOS status no/yes = 0/1). In this model, predictors of WBC were HOMA (? = 0.35; P < 0.0001) and PCOS status (? = 0.66; P < 0.0001). Moreover, simple linear regression analysis showed that for the entire population, the measure of HOMA was useful to predict CRP levels (? = 0.68; P < 0.0001). A multiple linear regression analysis was performed by adding to the previous model a second independent variable (PCOS status no/yes = 0/1). The predictor of CRP levels was PCOS status (? = 0.62; P < 0.0001) and not HOMA (? = 0.10; P = 0.43). Finally, multiple linear regression analysis showed that other hormone levels are not predictors of leukocyte count both in PCOS and control women.
Discussion
To the best of our knowledge, this is the first study in the literature to demonstrate an increased leukocyte count in PCOS. The results of this study show that insulin resistance is probably the main factor responsible for the increase of leukocytes in patients with PCOS.
Multiple regression analysis did not demonstrate that hormone levels are predictors of leukocyte count both in PCOS and control women, suggesting that leukocyte increase is not affected by elevated circulating concentrations of T, A, DHEAS, LH, 17-OHP, or E2. In comparison with matched controls, PCOS women had greater serum insulin concentration and HOMA index, confirming previous data (2). In our study, leukocyte count significantly correlates with either fasting insulin concentrations or estimates of insulin sensitivity, suggesting that increased insulin production affects perhaps WBC count. Furthermore, a significant linear correlation between WBC count and HOMA index, both in PCOS and controls, could explain the increase of leukocyte count in subjects with lower insulin sensitivity. A large body of evidence shows a correlative and causative relationship between inflammation and insulin resistance (23, 24) and a linear correlation between HOMA index and WBC count (12, 25, 26). Indeed, inflammation has been recognized to play a central role in both initiation and progression of the atherosclerotic process (7); therefore, elevated leukocyte count is directly associated with increased incidence of coronary heart disease, ischemic stroke, and mortality from cardiovascular disease in African-American and white men and women (9). In agreement with Kelly et al. (13), we also found increased CRP concentrations in women with PCOS, hence suggesting CRP as a predictor of cardiovascular events and independently related to insulin insensitivity (16). In fact, Festa et al. (16) reported, in a larger study, the relationship between CRP, fibrinogen, WBC count, and components of insulin resistance in a nondiabetic population. The association of leukocyte count with cardiovascular risk factors could be a manifestation of subclinical disease.
In conclusion, we suggest that women with PCOS appear to show higher levels of leukocyte count, a marker of low-grade inflammation and cardiovascular risk, than age- and BMI-matched controls.
Acknowledgments
We are indebted to Ms. Laura Carbonaro for editing the text.
Footnotes
First Published Online October 13, 2004
Abbreviations: A, Androstenedione; BMI, body mass index; CRP, C-reactive protein; DHEAS, dehydroepiandrosterone sulfate; E2, 17?-estradiol; HOMA, homeostasis model assessment; 17-OHP, 17-hydroxyprogesterone; P, progesterone; PCOS, polycystic ovary syndrome; PRL, prolactin; T, testosterone; TV-USG, transvaginal ultrasonography; WBC, white blood cell; WHR, waist/hip ratio.
Received April 2, 2004.
Accepted October 5, 2004.
References
Ovalle F, Azziz R 2002 Insulin resistance, polycystic ovary syndrome, and type 2 diabetes mellitus. Fertil Steril 77:1095–1105
Dunaif A 1997 Insulin resistance and the polycystic ovary syndrome: mechanism and implications for pathogenesis. Endocr Rev 18:774–800
Legro RS, Kunselman AR, Dodson WC, Dunaif A 1999 Prevalence and predictors of risk for type 2 diabetes mellitus and impaired glucose tolerance in polycystic ovary syndrome: a prospective, controlled study in 254 affected women. J Clin Endocrinol Metab 84:165–169
Arslanian SA, Lewy VD, Danadian K 2001 Glucose intolerance in obese adolescents with polycystic ovary syndrome and ?-cell dysfunction and risk of cardiovascular disease. J Clin Endocrinol Metab 86:66–71
Talbott E, Guzick D, Clerici A, Berga S, Detre K, Weimer K, Kuller L 1995 Coronary heart disease risk factors in women with polycystic ovary syndrome. Arterioscler Thromb Vasc Biol 15:821–826
Conway GS, Agrawal R, Betteridge DJ, Jacobs HS 1992 Risk factors for coronary artery disease in lean and obese women with the polycystic ovary syndrome. Clin Endocrinol 37:119–125
Alexander RW 1994 Inflammation and coronary artery disease. N Engl J Med 331:468–469
Wilson PW, Kannel WB, Silbershatz H, D’Agostino RB 1999 Clustering of metabolic factors and coronary heart disease. Arch Intern Med 159:1104–1109
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