Endocrine Abstracts

Introduction: The assessment of pituitary function is often achieved by means of sequential determinations (pool) of hormone levels such as prolactin and gonadotrophins. For the determination of prolactin levels the guidelines of the Endocrine Society are clear in recommending a single sample determination.

Objective: To evaluate differences between single sample and pool (0′, 20′ and 60′) determinations for assessing prolactin, FSH and LH levels.

Methods: We conducted a cross-sectional study including 4610 prolactin pools, 2628 FSH pools and 2568 LH pools performed between 2009 and 2011. Statistical analysis was performed using the paired samples t-test.

Results: We found differences between prolactin levels in determinations at 0′, 20′ and 60′ (21.5±64.6 vs 19.7±63.7 vs 18.8±63.8 ng/ml, P<0.001) and also between the prolactin level at 0′ and the mean of the three determinations (21.5±64.6 vs 20.0±63.9 ng/ml, P<0.001). The mean difference between prolactin levels at 0′ and 20′ was 1.8±7.6 ng/ml, at 0′ and 60′ 2.8±8.6 ng/ml and at 20′ and 60′ 1.0±7.1 ng/ml. Regarding FSH pools there were also found differences in hormone levels between determinations at 0′, 20′ and 60′ and between the FSH level at 0′ and the mean of three determinations (20.9±27.3 vs 20.1±20.4 vs 10.0±26.3 mUI/ml, P<0.001; 20.9±27.3 vs 20.3±26.6 mUI/ml, P<0.001), and the same was observed for LH pools (11.9±12.8 vs 11.4±12.3 vs 11.0±12.1 mUI/ml, P<0.001, 11.9±12.8 vs 11.4±12.3 mUI/ml, P<0.001). The mean difference between the FSH levels at 0′ and 20′ was 0.7±2.3 mUI/ml, at 0′ and 60′ 0.9±2.3 mUI/ml and at 20′ and 60′ 0.1±1.9 mUI/ml when considering LH pools the results were 0.5±2.2, 1.0±2.5, and 0.4±1.8 mUI/ml.

Conclusion: Despite the presence of differences in hormone levels between pool determinations these differences, given its range, do not appear to have clinical significance.