Background. The aim of this study was to assess acute biochemical changes after the administration of two different pharmaceutical forms of calcium carbonate or milk. Methods and Results. The group of 12 young (aged 20-27 years) and 12 older women (aged 63-71 years). After overnight fasting, each of the volunteers received a 1 g of elemental calcium in either form of the tested preparation: powder form of calcium carbonate - Vitacalcin pulvis (Slovakofarma, SR) or effervescent tablet - Calcium 500 mg Pharmavit (Pharmavit, MR) or in 250 ml of milk enriched with the milk calcium complex. Between each test the interval of 1-2 weeks was held. Samples of blond and urine esere taken in the fasting state before and during 5,5 h following ingestion of the calcium load. Both calcium carbonate and milk induced a signi%cant increase in the serum ionised calcium (iCa) and a significant decrease in plasma parathormone level (PTH) in Comparison with the baseline levels in both groups of women. Comparison between individual preparations and between preparations and milk did not reveal any significant differences in suppression of PTH. Comparison of the effects between young and elderly women did not show any statistically signi%cant difference in any measured parametrr. Conclusions. Our results confirmed the good bioavailability of calcium from milk and from both calcium preparations in both age groups of women. Signi%cantly more frequent hypercalcemia in the young women (p<0.05) and also the slightly higher hypercalciuria occurred after the application of calcium in the pharmaceutical form of effervescent tablet than after the application of calcium in the form of powder or after the application of milk.

        Key words: calcium, calcium carbonate, milk, parathormone.