Serum levels of retinol-binding protein 4 and adiponectin in women with polycystic ovary syndrome: associations with visceral fat but no evidence for fat mass-independent effects on pathogenesis in this condition.
BACKGROUND
Insulin resistance, which associates with levels of retinol-binding protein 4 (RBP4) and adiponectin, is implicated in the development of polycystic ovary syndrome (PCOS).


OBJECTIVE
The objective of the study was to explore the potential contribution of RBP4 and adiponectin in the etiology of PCOS and their relationships with specific fat depot measurements.


METHODS
This was a cross-sectional study.


METHODS
Serum RBP4 and adiponectin levels were compared between 50 PCOS cases and 28 female controls (including 22 body mass index/fat mass-matched pairs) and correlated with specific fat depot (including visceral) axial magnetic resonance imaging cross-sectional area measurements. All subjects were of U.K. British/Irish origin.


METHODS
Serum levels of RBP4 (automated immunonephelometric assay) and adiponectin [immunoassay: total and high molecular weight (HMW)]. Data are reported as geometric mean (sd, range) and optionally adjusted for fat mass and age.


RESULTS
Between the 50 PCOS cases and 28 controls, serum RBP4 levels were indistinguishable [39.0 microg/ml (31.0, 49.0) vs. 41.6 microg/ml (32.7, 52.9), respectively, unadjusted P = 0.24; adjusted P = 0.55]. Total (and HMW) adiponectin levels were lower in PCOS cases [total adiponectin 19.9 microg/ml (14.2, 27.8) vs. 25.8 microg/ml (17.7, 37.7), respectively, unadjusted P = 2.4 x 10(-3); adjusted P = 0.10]. For the paired-sample analyzes, there were no differences in RBP4 (P = 0.09), total adiponectin (P = 0.06), HMW adiponectin (P =0.19), or HMW to total adiponectin ratio (P = 0.98). In PCOS cases, L4-visceral fat area was associated positively with RBP4 (r(2) = 0.34, P = 0.01) and negatively with HMW to total adiponectin ratio (r(2) = -0.44, P = 1.3 x 10(-3)). Controls showed similar relationships.


CONCLUSIONS
Although associated with visceral fat, serum RBP4 and adiponectin levels do not play important, fat-mass-independent primary roles in the development of PCOS.
Barber
Thomas M
TM
Diabetes Research Laboratories, Oxford Centre for Diabetes, Endocrinology, and Metabolism, Churchill Hospital, Old Road, Headington, Oxford, United Kingdom. tom.barber@drl.ox.ac.uk
Hazell
Matthew
M
Christodoulides
Constantinos
C
Golding
Stephen J
SJ
Alvey
Christopher
C
Burling
Keith
K
Vidal-Puig
Antonio
A
Groome
Nigel P
NP
Wass
John A H
JA
Franks
Stephen
S
McCarthy
Mark I
MI
D052242:Adiponectin / Q000097:blood* / Q000502:physiology; D000328:Adult; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D050152:Intra-Abdominal Fat / Q000502:physiology*; D011085:Polycystic Ovary Syndrome / Q000097:blood / Q000209:etiology*; D054839:Retinol-Binding Proteins, Plasma / Q000032:analysis* / Q000502:physiology; D013739:Testosterone / Q000097:blood
D052242:Adiponectin; C101326:RBP4 protein, human; D054839:Retinol-Binding Proteins, Plasma; D013739:Testosterone