Biochemical measurements: Ionized calcium was measured immediately after blood collection with an ICA2 analyzer (Radiometer, Denmark); the interassay coefficients of variance were 3.3% and 2.7%, respectively, at concentrations of 0.77 mmol/L and 1.75 mmol/L. Serum phosphate, creatinine and alkaline phosphatase were quantified by automated colorimetry. Serum 25-hydroxy vitamin D and 1,25-dihydroxy vitamin D were measured after extraction with acetonitrile. 1,25-dihydroxy vitamin D was chromatographed on C-18 and silica cartridges before quantification 1,25-dihydroxy vitamin D assay. Serum PTH was measured by commercial radioimmunometric assay for intact human PTH (hPTH)- (Allegro Intact PTH, Nichols Institute Diagnostics, USA). This assay was initially reported to react only with hPTH- because available synthetic amino and carboxylterminal fragments did not react in the assay. Nonetheless, this and other commercial I-PTH assays have been demonstrated to react with a molecular form of PTH other than hPTH-in humans when sera obtained under various calcemic conditions were fractionated by high performance liquid chromatography. The non-PTH- molecular form represents approximately 20% of I-PTH in normal individuals. The reported detection limit of the assay is 0.1 pmol/L in the Nichol’s Institute brochure. The intra-assay coefficient of variance for duplicates is 3.1%. Best quality drugs are waiting – buy yasmin birth control to spend less time and money.