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Using a paired design as well as a cross-over design both with 16 h incubation periods, we have incubated human decidua in hyposmotic, isosmotic, and sodium chloride hyperosmotic media. In the cross-over design each tissue aliquot was subjected to 3 media with different osmolalities, one of which was isosmotic. Thus, intensive utilization of the tissue was possible. The results of the cross-over study were identical with the result of the paired design. We found a decreased secretion of prolactin in hyposmotic environments, whereas hyperosmotic environments up to an osmolality about 400 mmol/kg gave a dose related increase in the prolactin secretion into the medium as well as in the total content of prolactin in the tissue and the medium. Excessive hyperosmotic medium decreased the secretion.The enhanced secretion was an effect of increased production, which could be blocked by cycloheximide. We found no feedback of prolactin on its own secretion.

Serum levels of human placental chorionic somatomammotropin (HCS) were determined by radioimmunoassay (immunosorbent) in 800 pregnancies, normal as well as pathological. The normal group comprised 200 pregnant women (254 estimations). Correlation has been found to exist between the placental weight and the HCS levels as determined in the last few weeks before onset of labour.

The aim of the study was to assess the values of serum estradiol (E₂) in women undergoing ovarian stimulation with five direct commercial assays (IMX, Amerlite, Spectria, Vidas, CA) and to compare them with the results of an E₂ direct method used in our laboratory. The study included 12 infertile women. Thirteen cycles were monitored daily during ovarian stimulation with transvaginal ultrasound and serum E₂. Large differences were found between the E₂ concentrations measured on the same sample with the different methods. In general the IMX and Amerlite assays gave the highest and CA the lowest results. The results of our own RIA and Spectria assay agreed more closely. The median ratio of the highest E₂ value (IMX assay) and the lowest E₂ value (CA value) was 1.75 (1.30–3.15). Values of E₂ measured in serum depend on the method used. It is not possible to apply criteria from other studies directly to one’s own patients. Close collaboration between the laboratories and the clinical staff is essential.

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