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Context Hyperphosphatemia and high levels of fibroblast growth factor 23 (FGF23) are risk factors for cardiovascular events in patients with chronic kidney diseases. However, the impact of an inorganic phosphorus additive in healthy people is largely unknown. Objective We aimed to investigate the acute effect of excessive dietary phosphorus administered as sodium dihydrogen phosphate on the postprandial levels of Pi and FGF23 and the response to food. Methods This study was a double-blind placebo-controlled crossover study with 29 healthy male and female participants from the general community who were administered a single dose of either 700 mg phosphorus (NaH2PO4) or a sodium-adjusted placebo in combination with a test meal. Postprandial plasma levels of Pi and FGF23 were measured. Results Compared with placebo, oral phosphorus increased the plasma Pi level, which remained elevated during the ensuing 8 hours (at 480 minutes: 1.31 vs 1.16 mmol/l; P Conclusion An oral phosphorus load can induce elevated postprandial levels of circulating Pi for hours in healthy subjects, despite rapid homeostatic counterreactions. FGF23 levels and the postprandial response to food were not affected.

Eye irritation as monitored by the Draize test is primarily caused by the membrane-toxic effect of chemical substances. Arachidonic acid (AA) is an integral part of the cell membrane phospholipids and a substrate for inflammatory mediators formed in response to membrane-toxic events. It is rapidly released as a result of membrane disintegration or of enzymatic cleavage of phospholipids. In order to replace the Draize test by alternative methods, we examined the [3H]-AA release of U937 cells using the following substances: dimethylsulphoxide (DMSO), formamide, chloramine, dimethoate, 2,4-dichlorophenoxyacetic acid (2,4-D), sodium dodecyl sulphate (SDS), and lysolecithin. As revealed by the determination of maximum tolerated concentrations (MTC) and by calculation of both the linear correlation coefficient (r*) and the rank correlation coefficient according to Spearman (rs), a positive correlation (r* = 0.92; rs = 0.98; α = 5%) between the [3H]-AA release and the results of the Draize test was seen. It was attributed to the fact that the release of AA represents a key reaction of the inflammation process. The sensitivity of the in vitro method surpassed the Draize test by 1–2 orders of magnitude demonstrating the [3H]-AA release test to be a potentially suitable alternative to the eye irritation test.