Endocrine Abstracts

Objective

In polycystic ovarian syndrome (PCOS), C-reactive protein (CRP) concentration is elevated and inversely related to insulin sensitivity. However, no data exists on the biological variability of CRP in PCOS.

Methods

Blood samples were collected after an overnight fast at four-day intervals on 10 consecutive occasions from 12 patients with PCOS and 11 weight and age matched Caucasian women (controls). Duplicate samples of stored serum were analysed for CRP and insulin in a single batch. Bio variability data was analysed by calculating analytical, within subject, and between subject variances according to the methods of Fraser and Harris. Insulin resistance (IR) was calculated by the homeostasis model assessment method. All subjects gave their informed written consent prior to entering the study that had been approved by the Hull and East Riding Local Research Ethics committee.

Results

As with IR, CRP in the PCOS subjects was significantly greater than in controls. In contrast to IR, which was more variable in PCOS, the intraindividual variation for CRP was similar for both groups (1.63 vs. 1.76). The critical difference for sequential CRP values in PCOS was −64% and +179%.

Conclusions

The lack of concordance between the variability of CRP concentration and the variability of insulin resistance in PCOS compared to the controls, indicates that despite the known inverse relationship, the magnitude of CRP changes in the same individual do not seem to closely mirror those of insulin resistance. Therefore, an increased CRP concentration cannot be used as a direct surrogate marker to establish the presence of insulin resistance or metabolic syndrome in this group.