Kidney Failure Pathophysiology & Schematic Diagram

January 17, 2018 Modified date: September 25, 2020

Kidney Failure or otherwise known as renal failure or kidney injury can be categorized to either acute or chronic kidney failures, depending on the severity of the disease condition. Acute kidney failure is considered to be the abrupt loss of kidney function while chronic kidney failure is defined as the progressive reduction of renal functioning by which referring to the remaining kidney mass that can no longer sustain the needs of the body.

Causes of renal failure can be divided into three: (1) Pre- renal- referring to causes that interfere with renal perfusion, i.e. hypotension, decreased cardiac output and increased vascular resistance; (2) Renal – these are parenchymal changes from disease or nephrotoxic substances, such as infectious diseases, glomerulonephritis, and diabetes; and (3) Post Renal – factors referring to obstruction in the urinary tract like calculi or tumors.

There are several phases in acute kidney failure which includes the following:

Onset phase- which begins from the precipitating event to the development of symptoms.
Oliguric- anuric or nonoliguric phase – it lasts for 1 to 8 weeks and it is either oliguric (less than 400cc/day) or nonoliguric (urine output = 2, 000 cc/day)
Diuretic phase- urinary output may be as much as 1,000 to 2,000 cc/ day and GFR or the glomerular filtration rate returns to normal while BUN levels fluctuates
Recovery phase- it usually lasts for 3- 12 months with the possibility to resume the pre- renal failure level

Clinical Manifestations of Kidney Failure

1.Nonoliguric renal failure:

Urine output up to 2,000cc/ day
Diluted and nearly osmolar urine
Hypertension
Fluid overload
Tachypnea
Extracellular fluid depletion (dry mucous membranes, poor skin turgor)

2.Oliguric renal failure:

Urine output is below 400cc/day
Signs and symptoms may vary depending on the causation of condition, stated below

Pre- Renal	Renal	Post- Renal
High urine specific gravity Little or no proteinuria Elevated BUN: CR ratio	Fixed urine specific gravity High sodium concentration in urine Proteinuria Weight gain Edema Hemoptysis Anemia Hypertension	Fixed urine specific gravity Elevated sodium concentration in urine Little or no proteinuria