Kidneys work at the microscopic level. The kidney is not one large filter. Each kidney is made up of about a million filtering units called nephrons. Each nephron filters a small amount of blood. The nephron includes a filter, called the glomerulus, and a tubule. The nephrons work through a two-step process. The glomerulus lets fluid and waste products pass through it; however, it prevents blood cells and large molecules, mostly proteins, from passing. The filtered fluid then passes through the tubule, which sends needed minerals back to the bloodstream and removes wastes.
The incidence of both venous and arterial thrombosis are much higher in patients with nephrotic syndrome compared with estimates in the general population. The magnitude of this effect was illustrated in a retrospective study of 298 (predominantly adult) patients who presented with the nephrotic syndrome and were followed for a mean of 10 years [ 7 ]. The absolute risk of venous thrombosis was percent per year, which is eight times higher than the age- and sex-matched annual incidence reported in the Worcester DVT study [ 8 ]. The absolute risk of arterial thrombosis was percent per year, also approximately eight times that observed in a general population [ 9 ]. The risk of both venous and arterial thrombosis was greatest within the first six months of diagnosis (annual incidence and percent, respectively) [ 7 ].
Many of these diseases tend to occur more often in certain age groups: