If one has some damage in one’s kidneys then raised blood pressure greatly speeds up its further progress (to kidney failure). This development can be delayed or arrested by good control of blood pressure in anyone who shows signs of even minimal kidney damage, whatever its cause, and also in anyone who has diabetes. Kidney damage can be a complication of long-standing diabetes (usually combined with high blood pressure) and an occasional cause of (secondary) high blood pressure.
Early kidney damage is signalled by a rise in the blood levels of both urea and creatinine, and usually by protein in wine.
People with kidney failure and high blood pressure need either to avoid altogether those blood pressure-lowering drugs that are excreted through the kidneys, or greatly reduce the dose they take. All the blood pressure-lowering drugs need to be used cautiously and usually at lower doses, and the ACE inhibitor drugs and thiazide diuretics are particularly hazardous. Management of high blood pressure complicated by kidney failure is beyond the competence of GPs working alone, and should be shared with specialists in a renal (kidney) unit, who can advise on medication.
Chronic obstruction of the bladder usually by enlargement of the prostate, is a common and important cause of sustained high blood pressure. Blood pressure falls quickly to its original level after the obstruction is relieved by draining the bladder with a catheter or by operating on the prostate, so the problem may either go away or at least be reduced to a large extent.