Week 6 Flashcards
What is the normal renal blood flow?
~ 1000 to 1200 mL/min, or 20% to 25% of the cardiac output
What is GFR?
Filtration of plasma per unit of time, directly related to the perfusion pressure of renal blood flow
What regulates renal blood flow?
Sympathetic noradrenergic nerves that regulate vasoconstriction
What is the role of renin in renal function?
Secreted from juxtaglomerular cells, converts angiotensin I to angiotensin II, a potent vasoconstrictor
What do natriuretic peptides do?
Antagonize the RAAS and promote sodium chloride and water excretion
What are the three processes of urine formation?
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion and excretion
What is renal clearance?
How much of a substance can be cleared from blood by the kidneys per given amount of time
What is renal insufficiency?
Decline of renal function to approximately 25% of normal or a GFR of 25-30 mL/min
What is uremia?
Syndrome of renal failure characterized by elevated blood urea and creatinine levels
What is azotemia?
Increased serum urea levels and frequently increased creatinine levels due to renal insufficiency or failure
What defines acute kidney injury (AKI)?
Sudden decline in kidney function with decreased glomerular filtration and urine output
What are common causes of AKI?
- Extracellular volume depletion
- Decreased renal blood flow
- Toxic/inflammatory injury to kidney
What is the most common cause of prerenal AKI?
Renal hypoperfusion
What is acute tubular necrosis (ATN)?
A type of intrarenal AKI caused by ischemia or nephrotoxicity
What is the typical urine output in oliguria?
Less than 30 mL/hr
What is the pathophysiology of post-ischemic ATN?
Persistent hypotension, hypoperfusion, and hypoxemia leading to ischemia and tubular injury
What factors can cause nephrotoxic ATN?
- Radiocontrast media
- Antibiotics (aminoglycosides)
- Heavy metals
- Anesthesia
What is the result of post-renal AKI?
Urinary tract obstructions affecting both kidneys leading to increased intraluminal pressure
What are the phases of clinical progression in ATN?
- Initiation phase
- Extension phase
- Maintenance phase
- Recovery phase
What is the significance of nonoliguric renal failure?
Represents less severe injury and is associated with toxin exposure or drug toxicity
What diagnostic indicators are used for AKI?
- Ratios of BUN to plasma creatinine concentration
- Fractional excretion of Na+
- Cystatin C
What dietary changes are recommended for managing hyperkalemia?
- Restrict dietary sources of potassium
- Use non-potassium-sparing diuretics
What characterizes chronic kidney disease (CKD)?
Progressive loss of renal function associated with systemic or intrinsic kidney diseases
What are the common systemic diseases that can lead to CKD?
- Hypertension
- Diabetes mellitus
- Systemic lupus erythematosus
What is the intact nephron hypothesis?
Loss of nephron mass leads surviving nephrons to maintain kidney function through compensatory mechanisms
What contributes to the progression of CKD?
- Proteinuria
- Angiotensin II
What are common clinical manifestations of CKD?
- Hypertension
- Anorexia
- Nausea
- Vomiting
- Edema
- Anemia
What is the effect of CKD on sodium and water balance?
Increased sodium delivery to nephrons leads to less reabsorption and potential volume depletion
How does CKD affect potassium balance?
Tubular secretion of K+ increases until oliguria develops, leading to potentially dangerous serum levels
What happens to acid-base balance in early renal insufficiency?
Acid excretion and bicarbonate reabsorption increase to maintain normal pH
What happens to serum creatinine (SCr) as GFR decreases?
Serum creatinine increases
SCr is a good marker of changing glomerular function but is affected by muscle mass and fluid overload.
What is the effect of potassium-sparing diuretics like spironolactone on serum potassium levels?
They may precipitate increased serum potassium levels
This occurs as the disease progresses and total body potassium increases.
At what GFR level does metabolic acidosis develop?
When GFR decreases to 30%-40% of normal
In end-stage kidney disease (ESKD), metabolic acidosis may be severe enough to require dialysis.
What are the consequences of impaired renal synthesis of calcitriol?
Accelerates hypocalcemia
This is due to decreased intestinal absorption of calcium.
What are the effects of acidosis on calcium balance?
Leads to negative calcium balance
Hypocalcemia can cause secondary hyperparathyroidism and vitamin D deficiency.
What is the relationship between GFR and plasma urea levels?
As GFR decreases, plasma urea levels increase
Urea clearance varies with hydration status, making it a poor index for GFR.
What are the indicators of a catabolic state in kidney disease?
Proteinuria and negative nitrogen balance
Levels of serum proteins, including albumin, decrease, and there is loss of muscle mass.
What is the most common hematologic alteration in kidney disease?
Normochromic normocytic anemia
This is due to a lack of erythropoietin.
What are the major causes of morbidity and mortality in patients with chronic kidney disease?
Cardiovascular disease and dyslipidemia
Hypertension and anemia are also significant concerns.
What are common gastrointestinal symptoms associated with uremia?
Anorexia, nausea, vomiting, and mouth ulcers
Uremic fetor is bad breath caused by the breakdown of urea by salivary enzymes.
What is the primary treatment for uremic gastroenteritis?
Protein-restricted diet and sodium-based alkali
This helps relieve nausea and vomiting.
What is the function of erythropoiesis-stimulating agents (ESA) like epoetin alfa?
Stimulates erythropoiesis to reduce anemia
They interact with receptors on hematopoietic stem cells in the bone marrow.
What adverse effect is most common with erythropoiesis-stimulating agents?
Hypertension
There is also a risk of thromboembolic disease, TIA, and stroke.
What is the mechanism of action of loop diuretics like furosemide?
Inhibits reabsorption of sodium and chloride in the ascending loop of Henle
This leads to the excretion of Na+, Cl-, and water.
What is the desired effect of calcium carbonate in CKD patients?
Normalizes phosphate levels and neutralizes gastric acidity
It acts like intrinsic calcium.
What is the main indication for using cation exchange resins like polystyrene sulfonate?
Treatment of hyperkalemia
This is used in conjunction with other measures.
What are the major adverse effects of cation exchange resins?
Hypocalcemia, hypokalemia, and sodium retention
Monitoring for confusion and dyspnea is important.
Fill in the blank: As GFR decreases, the ability to concentrate and dilute urine _____
decreases
True or False: Fluid overload can lead to pulmonary edema in kidney disease.
True
What is the treatment for secondary hyperparathyroidism in CKD?
Dialysis and control of serum calcium and phosphate levels
This helps manage complications associated with renal disease.
