Renal Function (Ch. 33)-- Definition First Flashcards
- Amount of urea in blood
- Waste product of metabolism
- Not specific to kidneys
- Influenced by protein intake, GI bleed, dehydration
- Included on Basic Metabolic Panel (BMP)
Blood Urea Nitrogen (BUN)
-
Filter blood and reabsorb substances
- Electrolytes
-
Regulate pH
- Conserve or eliminate HCO3- & H+
-
Regulate osmolality of ECF & urine
- ADH
- Aldosterone (RAAS)
-
Endocrine functions
- Renin
- Erythropoietin
- Vitamin D
Functions of the Kidneys
- Average urinary output: 125 mL/hr
- Neural & humoral mechanisms
-
SANS, ADH, & Angiotensin II (RAAS) → Vasoconstriction
- ⇣ renal blood flow
-
Dopamine & NO → Vasodilation
- ⇡ renal blood flow
-
SANS, ADH, & Angiotensin II (RAAS) → Vasoconstriction
Renal Regulation
- Urinary obstruction
-
Renal pelvis
- Renal calculi (kidney stones)
- Pregnancy
-
Ureter
- Neurogenic bladder
- Uretovesicle junction stricture
-
Bladder & urethra
- Bladder stones
- BPH
-
Renal pelvis
Obstructive Disorders of Renal Function
- Volume of plasma filtered per minute
- BEST index of kidney function
Glomerular Filtration Rate (GFR)
Supersaturation → Solute precipitates → Stone formation
Urinary stasis → Crystal aggregation (around organic material) → Stone formation
Renal Calculi Mechanisms
- PAIN
-
Renal colic
- Acute, intermittent, excruciating
- N/V
-
Non-colicky
- Dull, deep, continuous ache
- Mild → Severe
-
Renal colic
Renal Calculi Clinical Manifestations
Drug exposure (NSAIDS, contrast media, diuretics, immunosuppressants) → Structural or functional changes in kidneys
NSAIDS/ASA → ⇣ PGs (renoprotective) → ⇣ Renal blood flow
Hypersensitivity (Methicillin + Furosemide/Thiazide Diuretic) → Tubulointerstitial nephritis
- High blood flow and filtration pressure in kidneys
- Exposed to toxins in blood
- Kidneys involved in metabolism of drugs
- Exposed to toxic drug metabolites
- Tolerance factors:
- Age
- ⇡ Risk: Elderly
- Renal function
- Hydration status
- Blood pressure
- Urinary pH
- Age
Drug-Related Nephropathies
-
[Solutes] in urine
- Normal range: 1.010-1.025
- High– Dehydration
- Low– ⇣ Renal function
- Normal range: 1.010-1.025
Specific Gravity
- Abrupt onset of shaking, chills, or fever
-
Constant ache in lower back
- Unilateral or bilateral
- Malaise
- N/V
- Abdominal pain
- Lower urinary tract symptoms
- Dysuria
- Increased urinary frequency
- Urgency
Acute Pyelonephritis Clinical Manifestations
- Calcium salts → Calcium stones (oxalate or phosphate)
- 70-80%
- Hyperparathyroidism, High fructose beverages
- Uric acid → Uric acid stones
- Gout, Tumor lysis syndrome, High purine diet
- Magnesium ammonium phosphate → Struvite
- Alkaline urine, Bacteria that split urea → ammonia & CO2
- Normal urine pH: 4.5-8
- Alkaline urine, Bacteria that split urea → ammonia & CO2
- Cystine → Cystine stones
- Cystinuria (autosomal recessive genetic defect)
- ⇡ Cystine resorption
- Cystinuria (autosomal recessive genetic defect)
Types of Renal Calculi
Expansion of the kidney with urine
- ⇡ Pressure inside renal capsule
- Compartment syndrome
- Blood vessels compressed
- Renal ischemia
- Necrosis of tissue
- Chronic renal failure
Hydronephrosis
-
Hematuria w/ red cell casts
- Sudden onset
-
Oliguria
- <20 mL/hr
- ⇣ GFR
- Azotemia
- ⇡ BUN
- Cola-colored urine
Acute Nephritic Syndrome Clinical Manifestations
- Acute nephritic syndrome
-
Rapidly progressive glomerulonephritis
- Goodpasture Syndrome
- Nephrotic Syndrome
Disorders of Glomerular Function
Determined by site, degree, and duration of obstruction
Urinary stasis → Infection & Renal Calculi
Dilation of renal collecting ducts → Hydronephrosis → Renal ischemia → Necrosis of kidney tissue
Acute emergency → Chronic renal failure
Urinary Obstruction Mechanisms
Lupus
Type III Hypersensitivity
Systemic lupus erythematosus→ Antigen-antibody complexes trapped in glomerular membrane → Inflammation → Lupus Nephritis
Diabetes
T1DM/T2DM → Diabetic glomerulosclerosis (thickening/scarring of basement membrane) → CKD → Renal failure, proteinuria, or nephrotic syndrome
- Mechanisms
-
⇡ BG → ⇡ GFR & glomerular pressure → Capillary pores enlarge
- Angiotensin II-mediated
- Improper synthesis of basement membrane
-
⇡ BG → ⇡ GFR & glomerular pressure → Capillary pores enlarge
- Manifestations
- Glomerular lesions
- Non-nephrotic proteinuria
-
Microalbuminuria
- 30-300 mg urinary albumin in 24hrs.
- Nephrotic syndrome
Systemic Causes of Glomerularnephritis
Glomerular basement membrane disturbed → ⇡ Permeability → Protein and lipids in urine
Filtration of proteins > Tubular reabsorption
Nephrotic Syndrome
Acute inflammation of the kidney caused by bacterial infection
Infection → Outflow obstruction + Vesicoureteral orifice incompetence → Vesicoureteral reflux
E. Coli, Klebsiella, Proteus
- Route of bacteria to kidney
- Ascending infection from lower urinary tract
-
UTI
- ⇡ Risk– Short intravesical ureter
-
UTI
- Through the bloodstream
- Staphylococcus aureus in blood (sepsis)
- Infective endocarditis
- Ascending infection from lower urinary tract
Acute Pyelonephritis
- Fluid & solutes filtered from capillary into Bowman space (filtrate)
- IN through AFFERENT
- OUT through EFFERENT
- Capillary membrane
- Endothelial layer
- Basement membrane
- Capsular epithelial layer
- Podocytes
- Particles move through “gaps”
-
Selectively permeable
- Water and small particles leave blood
- Larger particles prevented from leaving blood
- WBCs, RBCs, glucose, proteins…
-
⇡ Permeability w/ inflammation
- Glomerular damage
Glomerulus
