Mod 12 Renal Disorders Flashcards by Derrick Chuong

What is the primary function of the kidneys?

Clean blood and maintain homeostasis

Maintains blood volume; excrete excess (waste products)
Selective reabsorption of substances of Na, K, etc.
Vitamin D activation also occurs here

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What systems do the kidneys regulate to maintain homeostasis?

Any system that regulates/deals with Erythropoietin and renin/angiotensin levels

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How much cardiac output is received by the kidneys?

20-25%

1700 liters per day; produce about 60 ml/hr of urine
don’t waste time on this slide for now

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What are normal BUN values?

7-20 mg/dL

BUN = blood urea nitrogen. Measures the amount of urea nitrogen in the blood.
The liver produces urea as a waste product of protein digestion

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What are normal creatinine levels for men and women?

1.4 mg/dL for men and 1.2 for women

Creatinine = product of the breakdown of creatine phosphate from protein metabolism in the muscles.
Released at a constant rate by the body.

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What are expected general outcomes from Kidney Failure? (3)

Blood volume increases –> Increased risk of pulmonary edema
Electrolyte disturbances may manifest in cardiopulmonary symptoms (arrhythmias)
Metabolic acidosis

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How does acute kidney failure differ from chronic kidney failure?

A reversible state of acute impairment in renal function

Etiology can have prerenal, renal, and/or post renal causes

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How does chronic kidney failure differ from acute kidney failure?

Often irreversible, divided into 5 stages based on:

Amount of kidney function remaining
Symptoms
Estimated glomerular filtration rate (GFR)

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What is the Etiology of Prerenal failure?

Any disease that leads to inadequate perfusion of the kidney:

Shock states
Heart failure
Hypotension
Sepsis
Atherosclerosis of the renal artery
Rhabdomyolysis
Tubular and glomerular function remain normal

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What is the Etiology of Renal failure (intrinsic)? (3)

Any disease that leads to actual damage of the nephrons of the kidney:

Acute tubular necrosis (direct damage to kidney tissue)
Acute glomerulonephritis (vascular damage)
Acute interstitial nephritis (inflammation of kidneys; by meds)

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What is acute tubular necrosis?

Direct damage to the kidney tissues; especially the tubule

Ischemic or cytotoxic in origin
A common cause of kidney failure in hospitalized patients

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What are possible causes of Acute Tubular Necrosis? (4)

Blood transfusions
Low perfusion for > 30 mins
Major surgery
Septic shock

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What is Acute Glomerulonephritis?

Vascular in origin; the glomerulus becomes inflamed and damaged

Often due to auto-immune response or infections

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What is Acute interstitial nephritis?

Acute interstitial nephritis

Inflammation of the kidneys; often caused by a medicine

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What is the Etiology of Postrenal failure?

Mechanical obstruction of the urinary collecting system (ureters, bladder, urethra…); Increased tubular pressure decreases the filtration driving force by…

Stone disease
Tumors
Stricture
Thrombosis
Compressive hematoma
Enlarged prostate

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Clinical manifestations of Acute Renal Failure? (4)

Depend on etiology, but generalities include:

Urine output abnormalities (oliguria or Anuria)
Electrolyte imbalances; and following weakness
Fluid loss via Nausea and vomiting
Fluid overload –> pulmonary edema and its manifestations

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What is Oliguria?

Failure to produce adequate urine

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What is Anuria?

Total failure to produce urine

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Pathophysiology of Acute Renal Failure?

Initial kidney deficiency (compensation failure and decreased u/o)
Retention of nitrogen waste and fluid overload
Renal acidosis by filtration failure (acid base dysfunction)
Electrolyte imbalance (i.e hypernatremia)

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What are common Electrolyte imbalances associated with acute renal failure?

Hypernatremia
Hyperkalemia
Hyperchloremia

What are the consequences of nitrogen waste retention?

Retention of waste products leads to fluid overload and increased extracellular fluid

Waste products would be urea, uric acid, and creatinine

What happens if the kidneys cannot excrete fixed acids?

Renal acidosis (acid/base dysfunction)

What are normal lab findings of urine?

Yellow-amber in color - clear to slightly hazy

pH 4.6-4.8
Negative of glucose, ketone, protein, bilirubin, crystals
Rarely shows RBC, WBC, epithelial cells, casts
Normal BUN and creatinine
Specific gravity of 1.010-1.025?

What are abnormal lab findings of urine that would indicate Acute Renal Failure?

Increased BUN and creatinine

urinalysis may reveal sedimentation, WBC, and RBCs

What are treatments or management strategies for acute renal failure?

**Dialysis and Diuretics** are the primary tx for renal failure. 1. Pretreatments; identify and treat causal agent 2. Monitor in/out for fluid overload 3. **Monitor electrolytes, Potassium levels** 4. Monitor for anemia - Other interventions **correct or monitor pt status not worsen the causal agent**. - Rule of thumb before primary tx: **Ensure proper circulation and filtration**

If circulation is the causal agent of renal failure, what are 2 variables that need to be maintained/corrected?

Identify the cause and treat it first. Ensure proper circulation and filtration. 1. Restore circulation w/volume expanders, vasopressors, blood volume 2. Restore circulation to kidney, remove neoplasms, clear obstructions

Why do you need to monitor anemia if acute renal failure is suspected?

Kidneys produce erythropoietin which commands stem cells in the marrow to form RBCs. They are markers of kidney status.

What should you keep in mind when managing Acute Renal Failure pharmacologically?

Beware of inefficient drug elimination - Ensure meds are cleared by kidneys, they could linger longer.

What are patients at risk of during periods of low renal blood flow?

Iatrogenic renal injury (caused by tx or meds) such as: - Radio-contrast dyes - Aminoglycosides - CV surgery - Some other meds (NSAIDS, ACE inhibitors)

What are 3 types of Dialysis?

1. Peritoneal 2. Continuous Renal Replacement Therapy (CRRT) 3. Hemodialysis

What is Peritoneal dialysis?

Tube inserted into abdomen, dialysis solution is exchanged

What is CRRT (Continuous Renal Replacement Therapy) dialysis?

An extracorporeal purification therapy to substitute for impaired renal function over an extended period of time - **Slow dialysis** that has less dramatic swings in fluid balance - Better suited to the ICU patient

What is Hemodialysis?

A vascular access is created usually in a forearm A-V fistula (“shunt”) - usually 3 weeks - inpatients or outpatients

What are the 5 Diuretics classes used to manage Acute Rental Failure? - **Know this card** - know at least 1 drug in each group

1. Loop Diuretics (eg. Lasix) 2. Potassium-Sparing Diuretics (eg. Aldactone) 3. Carbonic Anhydrase Inhibitors (eg. Diamox) 4. Thiazide Diuretics (names end in zide, eg. hydrochlorothiazide (Microzide)) 5. Osmotic Diuretics (Mannitol, very powerful)

What diuretics affect each of the tubule pathway in the renal system?

What is chronic renal failure defined as?

Kidney disease lasting longer than 3 months

What are the most common causes of chronic renal failure (CRF)? - Other causes?

1. Type 1 and 2 Diabetes 2. Hypertension

What does the following image compare?

Compares a Normal and Polycystic kidney

What are clinical manifestations of Chronic Renal Failure (CRF)?

**May not have any symptoms until considerable, often irreparable, damage has occurred**

What are treatments for Chronic Renal Failure (CRF)?

Depends on stage of CRF: - Identify the cause and try to reverse/stop/slow it - Monitor creatinine, BP, and general health - Pt education - Dialysis (including creation of access site) - Transplant

What effect does PPV have on the renal system?

PPV can reduce urine output - Associated w/reduction in renal blood flow, glomerular filtration rate, Na and K excretion - **Decreases mean arterial pressure**

How does PPV affect hormonal systems that regulate Sodium and water retention? (3) *not done yet*

1. PPV enhances ADH release (via intrathoracic pressure diff) 2. PPV reduces atrial filling pressure causing decreased secretion of ANP 3. Renin angiotensin/aldosterone activation leading to increased Na and water retention

What does the Atrial Natriuretic peptide (ANP) Hormone do?

A cardiac hormone whose main function is to lower BP and to control electrolyte hemostasis. - Acts to increase glomerular filtration rate (GFR) - PPV can reduce ANP secretion (bc of reduced atrial filling pressure) - *Background info* Release of ANP is stimulated by increased atrial stretching which occurs w/elevated blood volume and pressure in the atria.

What is Naturiuresis?

Excretion of sodium in the urine

What is Diuresis

Increased urine production

What is the impact of decreased Atrial Natriuretic Peptide (ANP) on the body?

ANP normally counteracts the effects of aldosterone. When there is decreased ANP secretion, there is **less inhibition of aldosterone**. - **Causes a increase in sodium and water retention**

What is the function of the hormone ADH?

Chemical produced in the brain that causes the kidneys to release less water, decreasing the amount of urine produced. - High ADH levels = less urine production - Low ADH levels = greater urine production