Parathyroid Hormone (PTH) Whole & Intact is a modified VAST version of PTH in which both 3rd Gen (whole) and 2nd Gen (intact) can be measured. While 2nd Gen is more commonly used with a faster procedure, 3rd Gen has the advantage of not interacting with PTH fragment (7-84) -- which is not biologically active yet secreted significantly in uremic patients. Therefore for this population, especially when directing medication, 3rd Gen / Whole PTH is the more appropriate test.