With acute diffuse proliferative glomerulonephritis caused by systemic lupus erythematosus, why would a patient have uremia and hyperkalemia?

SLE DPGN is bad.: The degree of remaining renal function dictates the inability of the kidney to excrete waste products and manage potassium levels. In any severe kidney disease when egfr approaches 15 ml/min uremia and elevated k+ levels are frequently noted.

Lupus nephritis : This disorder results in the immune system attacking the kidney filters, leading to loss of kidney function. If severe enough, it can lead to build up of toxins that are normally removed from the blood by the kidneys, a condition known as uremia. Excess potassium from our diet is removed by the kidneys as well, so with damaged kidneys, potassium levels can become too high, called hyperkalemia.