Kidney disease: Nursing pathophysiology

Kidney disease occurs when kidney function declines, disrupting the regulation of fluids, electrolytes, waste products, and acid-base balance. Acute kidney injury, or AKI, is a sudden decline in kidney function that’s typically reversible, whereas chronic kidney disease, or CKD, is kidney damage that is gradual and irreversible.

Now, the kidneys are the body’s natural blood filter. They regulate what’s in the blood, clearing it of metabolic waste and toxins and excreting them through urine. They’re essential in regulating fluids and electrolytes; maintaining acid-base balance; secreting hormones essential for regulating blood pressure and stimulating the production of red blood cells; and activating vitamin D.

Within each kidney, there are millions of tiny functional units called nephrons, which consist of a renal corpuscle and renal tubules. The renal corpuscle is where blood filtration occurs, and it includes a tiny bundle of capillaries called the glomerulus, and the glomerular capsule, or Bowman’s capsule, which is a cup-shaped structure that surrounds the glomerulus.

As blood flows through the glomerulus, an ultrafiltrate of blood is created, which is then collected by Bowman’s capsule. Then, as it moves into the renal tubules, the filtrate is modified according to the body’s needs and urine is produced, in which waste is eliminated. The rate at which filtration takes place is called glomerular filtration rate, or GFR for short, and it’s one of the main measures of kidney function.

Now, there are three different mechanisms that can cause kidney injury. First, prerenal kidney injury can occur when there’s decreased blood flow to the kidneys like from dehydration, hemorrhage, or shock. In certain individuals, medications like non-steroidal anti-inflammatory drugs, or NSAIDs; angiotensin-converting enzyme, or ACE, inhibitors; or angiotensin receptor blockers, or ARBs, can also cause prerenal kidney injury by altering the normal autoregulation of blood flow within the kidneys.