Renal System Flashcards
Kidney Function
Regulate electrolyte concentration, acid-base balance, and amt of body fluids Detoxify and eliminate wastes Help control blood pressure (renin) Aid in RBC formation (erythropoiesis) Activates Vitamin D
Urine formation
GFR regulated by afferent & efferent arteriole constriction and relaxation
Actual urine excretion is ~1.5 L a day
Proximal convoluted tubule reabsorbs about 60% of nutrients and ions in the urine
The amount of a solute it can reabsorb is the transport maximum
Nutrients not reabsorbed pass out in the urine when renal threshold is reached.
Urine formation pt. 2
Loop of Henle
Controls concentration of urine
Reabsorbs more sodium & chloride than water
Ascending limb impermeable to water; solutes reabsorbed into blood supply, but water remains in the filtrate
Filtrate (now dilute) enters the distal convoluted tubule- “diluting segment”
Allows for excretion of free water
Late distal tubule & collecting tubule
Action of aldosterone
Regulation of K+ excretion
Serum Creatinine
0.6-1.2 mg/dL
Used as screening test for renal function
Inversely r/t GFR (low Creatine/High GFR)
A product of creatine metabolism in muscles therefore less accurate in elderly persons w/ decrease in muscle mass
Tells you more about kidney damage
BUN
8 – 20 mg/dL
Byproduct of protein metabolism
r/t GFR but less specific than creatinine
Influenced by protein intake, GI bleeding , & hydration status
Urinary tract infections (UTI)
The second most common bacterial infection seen by health care providers, effects more immunocompromised patients
Etiology Gram Negative Bacteria E-coli Staphylococcus saprophyticus Proteus mirabilis, Klebsiella pneumoniae, Enterobacter, Pseudomonas Gram-positive Staphylococcus aureus, group B streptococcus Complicated UTIs
Protection methods: Washout phenomenon Protective mucin layer Local immune responses and IgA Normal bacterial flora Lactobacillus in urethra of women Men: prostatic fluid protects urethra
Risk factors for UTI
Anatomical or structural factors Sexual activity Delayed postcoital urination Impaired voiding Catheters, other urinary instrumentations Constipation Reduction of estrogen
Signs and Symptoms for UTI
Frequency Urgency Dysuria: burning sensation Hematuria Cloudy, foul-smelling urine Flank pain (lower back) Elderly: Vague, abdominal discomfort & confusion
UTI Diagnosis
History and physical Urinalysis Proper collection is essential! Blood, WBCs, Nitrites (gram negative) Urine culture The GOLD STANDARD for diagnosis of complicated UTI ≥ 10,000/mL
UTI Prevention
Fluids Empty bladder Hygiene Cranberry juice Postcoital urination
TREATMENT:
Antibiotics
Force fluids
Acute Pyelonephritis
Complicated upper urinary tract infectious, inflammatory process, with abscess formation and tubular necrosis
Risk factors: UTI Vesicoureteral reflux Pregnancy Diabetes Catheter Immunosuppression Kidney stones
S/S of Acute Pyelonephritis
Symptoms of UTI plus…
Sudden onset fever, chills, unilateral or bilateral flank or groin pain. Pyuria, CVA tenderness. Possible sepsis and development of renal failure.
Geriatric –low-grade fever, malaise, confusion
Infants – irritability, poor skin perfusion, failure to thrive, GI symptoms, etc.
Can lead to renal scarring and damage
KIDNEY STONES
AKA kidney stones; nephrolithiasis; urolithiasis
More common in the United States than the rest of the world
Dietary preference – Foods high in animal protein
More common in white men
Before age 50
Negative risk factor: adequate fluid intake & regular physical activity
Kidney Stone Formation
Supersaturation of one or more salts: Presence of a salt in a higher concentration than the volume is able to dissolve the salt
Precipitation of a salt from a liquid to a solid state
Temperature and pH
Growth into a stone via crystallization or aggregation
Process by which crystals grow from a small nidus or nucleus to larger stones
Embedded in matrix
Presence or absence of stone inhibitors
Alkaline urinary pH: Increases the risk of calcium phosphate stone formation.
Acidic urine: Increases the risk of a uric acid stone.
Potassium citrate, pyrophosphate, and magnesium: Prevent stone formation.
Types of Stones
Calcium stones- ** Most common **
Calcium oxalate or calcium phosphate or combo
Struvite stones- contain magnesium ammonium phosphate
Associated w/ UTI & alkaline urine
Usually too large to pass. Lithotripsy or surgical removal
Uric acid stones (gout)
Cystine Stones- rare
Hydronephrosis
Result of continued urine outflow obstruction
Urine-filled dilatation of renal pelvis and calyces associated with progressive atrophy of the kidney
Kidney eventually destroyed
Signs & Symptoms Pain S&S of UTI Manifestations of renal dysfunction Impaired ability to concentrate urine
Glomerulopathies
Disorders that directly affect the glomerulus
Primary glomerular injury versus secondary
Significant cause of chronic kidney disease and end-stage renal failure worldwide
NEPHROTIC SYNDROME
Excretion of 3.0 g or more of protein in urine
Protein excretion as a result of glomerular injury
Clinical manifestations
Hypoalbuminemia
Peripheral edema
Prone to infection
Treatment
Normal-protein (1 g/kg body weight/day) and low-fat diet, salt restriction, diuretics, immunosuppression, and heparinoids
Immunosuppressive drugs and angiotensin-converting enzyme inhibitors used when steroid-resistant
Classification of Kidney Dysfunction
Acute or chronic; reversible or irreversible
Renal insufficiency
Decline of renal function to approximately 25% of normal
Renal failure
Significant loss of renal function
End-stage renal failure
Less than 10% of renal function remains
When Kidneys Fail…
Less waste is removed More waste remains in the blood Nitrogenous compounds build up in the blood BUN: Blood urea nitrogen Creatinine
Acute kidney injury
Sudden decline in kidney function with a decrease in glomerular filtration and accumulation of nitrogenous waste products in the blood
Increase in serum creatinine and blood urea nitrogen
Classification
RIFLE: Risk; Injury; Failure; Loss; End-stage disease
Criteria to guide the diagnosis of renal injury
Prerenal Acute Kidney Injury
Decreased blood supply
Shock, hemorrhage, dehydration, heart failure, vasoconstriction decreasing renal perfusion
Ex: Rhabdomyolysis, Hypotension
Intrarenal or Intrinsic Acute Kidney Injury
Intrarenal or Intrinsic
Kidney tubule function is decreased
Prolonged renal ischemia, nephrotoxic agents, acute pyelo, glomerulonephritis
Ex: Glomerular nephritis, Severe Rhabdomyolysis
Postrenal Acute Kidney Injury
Urine flow is blocked
Stones, tumors, enlarged prostate
Ex: Kidney stones, tumor/prostate compression
Hyperkalemia Treatment??
Restrict dietary sources of potassium.
Use non–potassium-sparing diuretic agents, or use cation-ion exchange resins.
Administer glucose and insulin or sodium bicarbonate to drive potassium into the cells. (Treat hyperglycemia)
Administer calcium (for heart)
May need dialysis.
Azotemia
Adopt a low-protein, high-carbohydrate diet.
Recovery
May take up to a year.
Chronic kidney disease
Progressive loss of renal function associated with systemic diseases
Kidney damage: GFR less than 60 mL/min/1.73 m2 for 3 months or more, irrespective of cause
Clinical manifestations: Do not occur until renal function declines to less than 25% of normal
Risk factors for Chronic kidney disease
Diabetes** Hypertension Glomerulonephritis Polycystic kidney disease Collagen diseases such as SLE
Diagnosis for Chronic kidney disease
Early detection is essential Urinalysis: presence of foamy protein Blood Urea Nitrogen (BUN) Creatinine Clearance/24 Urine collection Urine osmolality Electrolyte disturbances Acid/Base disturbances: metabolic acidosis
