Ch. 34 Acute Kidney Injury and Chronic Kidney Disease

What is the essential function of the kidneys?

Excretion and filtration of nitrogenous wastes.

Note: Kidneys clean your blood like a filter, getting rid of toxic stuff.

Name other key functions of the kidneys besides waste removal.

Electrolyte and volume regulation, drug elimination, hormone synthesis (like erythropoietin), protein metabolism, acid-base balance, bone and mineral homeostasis.

Note: Kidneys are like a multitasking helper for your body.

How do kidneys help bone and mineral homeostasis?

They balance calcium and phosphorus, activate Vitamin D to calcitriol, and remove excess phosphorus.

Note: Kidneys help bones stay strong and healthy.

What is Blood Urea Nitrogen (BUN)?

A non-protein nitrogenous waste produced from protein metabolism.

Note: BUN is leftover stuff from breaking down food protein.

How is BUN formed?

Amino acids are deaminated to ammonia, then converted to urea in the liver.

Note: It's like turning smelly ammonia into something your kidneys can flush.

Why is creatinine a better indicator of kidney function than BUN?

It is less affected by diet and is produced steadily from muscle metabolism.

Note: Creatinine is like a more reliable “kidney meter.”

What is the gold standard for screening and staging chronic kidney disease?

Urine albumin-to-creatinine ratio (ACR).

Note: Checks if protein is leaking into your pee.

What is the Glomerular Filtration Rate (GFR)?

The rate at which the glomerulus filters plasma to produce urine.

Note: Measures how fast kidneys can filter your blood.

Define renal failure.

Kidneys fail to remove metabolic waste and regulate fluids, electrolytes, and pH.

Note: Kidneys can’t do their cleaning job properly.

What is the difference between Acute Kidney Injury (AKI) and Chronic Kidney Disease (CKD)?

AKI is sudden and often reversible; CKD is slow and irreversible over months or years.

Note: AKI is like a sudden spill; CKD is a slow leak.

Define azotemia and uremia.

Azotemia: nitrogenous waste accumulation (like BUN and creatinine) in blood.
Uremia: clinical symptoms from advanced kidney failure.

Note: Azotemia = smelly blood; uremia = feeling sick from it.

What are the two most common causes of kidney failure?

Diabetes and hypertension.

Note: High sugar and high blood pressure hurt kidneys.

How does the kidney maintain Glomerular Filtration Rate (GFR) in early CKD?

Remaining nephrons hyperfilter and grow larger.

Note: Healthy nephrons work extra hard to compensate.

What are the three main categories of AKI causes?

Prerenal, intrarenal, and postrenal.

Note: AKI can be from before, inside, or after the kidneys.

What is Prerenal AKI?

Kidney injury from poor blood flow to nephrons.

Note: Kidneys don’t get enough water or blood to work.

What is a clinical sign of Prerenal AKI?

Sharp decrease in urine output and high BUN:creatinine ratio.

Note: Less pee, blood gets “stuck” with waste.

What is the most common intrarenal (intrinsic) cause of AKI?

Acute Tubular Necrosis (ATN).

Note: Kidney tubes get injured from toxins or low blood flow.

Name another cause of intrarenal AKI.

Acute interstitial nephritis.

Note: Inflammation inside the kidney can also block function.

Name a severe coagulation disorder that can cause ischemic Acute Tubular Necrosis (ATN).

Disseminated Intravascular Coagulation (DIC).

Note: Blood clots block tiny kidney vessels.

What is Postrenal AKI?

Obstruction of urine outflow from kidneys, ureter, bladder, or urethra.

Note: Pee can’t get out, so kidneys back up.

What is the most common cause of Postrenal AKI?

Bladder outlet obstruction.

Note: Something blocks the exit of the bladder.

What is the earliest symptom of kidney damage in CKD?

Polyuria (increased urination).

Note: Kidneys can’t concentrate urine, so you pee more.

List general signs of advanced CKD (uremia).

Weakness, fatigue, nausea, vomiting, metallic taste, weight loss, pruritus, mental changes, dyspnea, peripheral edema.

Note: Feeling sick all over when kidneys fail.

According to KDIGO, what GFR defines End-Stage Renal Disease (Stage 5 CKD)?

GFR <15 mL/min.

Note: Very little kidney function left.

What is Renal Osteodystrophy (CKD-MBD)?

Bone disease from CKD, involving calcium, phosphorus, PTH, and Vitamin D abnormalities.

Note: Kidneys can’t keep bones strong.

What childhood bone disorder occurs from CKD?

Renal rickets.

Note: Soft, weak bones in kids due to low Vitamin D.

What causes anemia in CKD?

Low erythropoietin production.

Note: Kidneys make less hormone to make red blood cells.

Why is cardiovascular disease a concern in CKD?

Leading cause of death in CKD, not kidney failure.

Note: Heart problems are common when kidneys are sick.

What cardiac problem is caused by CKD?

Uremic cardiomyopathy with left ventricular hypertrophy.

Note: Heart muscle gets thick from kidney disease.

What life-threatening ESRD complication affects the heart?

Uremic pericarditis.

Note: Heart lining gets inflamed from waste buildup.

Why are bleeding and clotting problems common in CKD?

Because of coagulopathies and altered platelets from uremia.

Note: Blood becomes unpredictable with kidney failure.

Name three GI symptoms of CKD.

Dysgeusia, anorexia, dyspepsia.

Note: Taste changes, poor appetite, and indigestion.

Name a neuromuscular symptom in CKD.

Restless legs syndrome.

Note: Nerves and muscles twitch and ache.

What is Dietetic-Nutritional Therapy (DNT) in CKD?

A diet plan to maintain nutrition, correct complications, and delay dialysis.

Note: Eating carefully helps kidneys last longer.

Why adjust drug dosing in CKD?

Kidneys can’t clear drugs properly, risking toxicity.

Note: Medicine can build up if kidneys don’t work.

What is Hemodialysis?

Filters blood through a machine called a dialyzer using two needles.

Note: Artificial kidneys clean blood.

Name three complications of Hemodialysis.

Intradialytic hypotension, muscle cramps, dialysis disequilibrium syndrome.

Note: Side effects from rapid fluid and waste shifts.

What is Peritoneal Dialysis?

Uses the peritoneum to filter blood with dialysis fluid.

Note: Abdomen acts like a natural kidney filter.

Name the two main types of Peritoneal Dialysis.

Continuous ambulatory (CAPD) and automated (machine-assisted) peritoneal dialysis.

Note: Manual vs machine exchange.

What is the main infection-related complication of Peritoneal Dialysis?

Peritonitis.

Note: Infection of the abdomen lining.

Name two non-infectious complications of Peritoneal Dialysis.

Weight gain and hernia.

Note: Extra fluid can cause pressure and bulges.

What is the preferred ESRD treatment for long-term survival?

Kidney transplantation.

Note: Replaces kidney for better life quality.

Name two contraindications for kidney transplantation related to behavior.

Non-adherence to medications and ongoing substance abuse.

Note: Patients must take care of their new kidney.

Q: What percentage of cardiac output do the kidneys receive?

A: About 25% of the body’s cardiac output.

Note: Kidneys are very busy filtering blood all the time.

Q: What type of proteins do the kidneys metabolize besides filtering waste?

A: Low molecular weight proteins, like insulin.

Note: Kidneys help break down small proteins, not just pee out stuff.