Alterations of Renal and Urinary Tract Function

Question 1

Renal dysfunction

Answer 1

Can be affected by: infection (most common), obstruction, or dysfunction (kidney disorders or systemic disease)

Types of dysfunction:
1. Vascular

2. Pre-renal (hypoperfusion; dehydration, CHF)
3. Intrinsic: nephrotic or nephritic syndrome, acute tubular necrosis, interstitial nephritis
4. Post-renal (obstructive)

Question 2

Urinary tract obstruction

Answer 2

Interference with flow of urine at a single site along the urinary tract that increases risk of infection and impairs renal function

Obstructive uropathy: anatomic changes (dilation) in the urinary system/structures r/t an obstruction (it is a finding, not a primary disease)

Question 3

Upper urinary tract obstruction

Answer 3

Compression of calyx (within kidney), ureteropelvic junction (between renal pelvic and ureter), and/or at the ureterovesical junction (before bladder)

Caused by: Stones, compression from abnormal vessel, tumor or abdominal inflammation, scarring

Increased pressure transmits back to glomerulus to decrease renal blood flow and GFR

Question 4

Hydronephrosis

Answer 4

A condition characterized by excess fluid in a kidney due to a backup of urine that results in renal pyramid infarction, nephron destruction, and scarring

Question 5

Renal calculi

Answer 5

Kidney stones in the kidney or urinary tract that are made of crystals, protein, or other substances

Common cause of urinary tract obstruction in adults; S/S: severe, intermittent pain, urinary urgency and frequency, hematuria

Composition (and classification):
1. Calcium oxalate and calcium phosphate (70-80%): precipitate to form in the renal pelvis; NOT recommended to cut dietary calcium since it binds to dietary oxalate in the gut

2. Struvite (magnesium, ammonium, phosphate; 15%): Proteus mirabilus (infection) resulting in alkaline urine and large struvite stones; associated with UTI, infections
3. Uric acid (7%)

Question 6

Lower urinary tract obstructions

Answer 6

Disorders of the bladder (primarily to urine storage/emptying)

Caused by: urinary incontinence, neurogenic bladder, urethral obstruction (stricture, prostate, tumor), pregnancy

Question 7

Urinary tract infection (UTI)

Answer 7

Inflammatory infection in any part of the urinary system; usually caused by gut bacteria

Risk factors: Premature newborns, pre-pubertal children, pregnant and sexually active women, females treated with antibiotics, spermicide users, estrogen deficient and/or post-menopausal women, indwelling catheters, DM, neurogenic bladder, obstruction

S/S: Polyuria, dysuria, urgency, low back and/or suprapubic pain; can be asymptomatic

Dx: Urine culture (>10,000/mL); treated with antibiotics

Protective mechanisms: Urination (low pH, high urea; urothelial bactericidal effect), Tamm-Horsfall protein (secreted from Loop of Henle), ureterovesical junction closes to prevent urine back flow into ureters, mucus-secreting glands, length of male urethra, Lewis blood group

Question 8

UTI classifications

Answer 8

Uncomplicated: mild; occur in people with normal urinary tracts

Complicated: include fever and develop when there is an abnormality in the urinary tract and/or immune-compromising condition (spinal injury, HIV, DM)

Recurrent: >3 UTIs in 12 mos. or >2 in 6 mos.

Pyelonephritis: a type of UTI that generally begins in the urethra or bladder and travels to the kidneys; presents with fever, chills, N/V/

Question 9

Glomerulopathies

Answer 9

Glomerular disorders classified as nephrotic or nephritic

Significant cause of CKD and end-stage renal failure

Question 10

Acute glomerulonephritis

Answer 10

Inflammation and subsequent damage of the glomeruli leading to proteinuria (nephrotic syndrome), and hematuria and azotemia (nephritic syndrome)

Caused by:
1. Primary glomerular injury: immunologic responses, ischemia, free radicals, toxins, vascular disorders, infection

2. Secondary glomerular injury: systemic diseases (DM, lupus), CHF, HIV

Question 11

Nephrotic syndrome

Answer 11

A kidney disorder that causes massive loss of PROTEIN (>3 g/day), lipid, and microscopic/no blood

S/S: Frothy urine, anasarca, increased risk for infection

Question 12

Nephritic syndrome

Answer 12

Urine contains massive amounts of BLOOD and varying degree of protein (0.3-3 g/day)

Advanced stages: systemic HTN, uremia, oliguria

Caused by increased permeability of the glomerular filtration membrane which allows RBCs and large proteins to pass

Question 13

Chronic Glomerulonephritis

Answer 13

Glomerular disease with a progressive course leading to chronic kidney failure

Secondary to (commonly):
1. Diabetic nephropathy: poorly controlled diabetes causes damage to blood vessel that cluster in kidneys (inability to filter waste from blood)

2. Lupus nephritis: lupus autoantibodies affect structures in kidneys that filter out waste causing inflammation; may lead to proteinuria, hematuria, systemic HTN, impaired kidney function, kidney failure

Question 14

Acute Kidney Injury (AKI)

Answer 14

A sudden decline in kidney function with a decrease in GFR and oliguria (UOP <400 mL/day), and accumulation of nitrogenous waste products in blood

Commonly due to: (1) ECF volume depletion, (2) decreased renal perfusion, or (3) toxic/inflammatory injury to kidney cells

Affects ~5% of hospitalized pts (a majority in the ICU); mortality of 50-80%

Classification:

1. Pre-renal (hypo-perfusion)
2. Intrinsic (disorders of renal parenchyma)
3. Post-renal (obstruction)

Question 15

Pre-renal AKI

Answer 15

Most common cause of AKI; results from renal hypoperfusion

Ex.: Hypotension, hypovolemia, sepsis, inadequate CO, multiple organ dysfunction, renal vasoconstriction (NSAIDs, radiocontrast agents), renal artery stenosis, kidney edema

Question 16

Intrinsic AKI

Answer 16

Occurs when direct damage to the kidneys causes a sudden loss in kidney function

Caused by: ischemic acute tubular necrosis or ATN (most common), nephrotoxic ATN, acute glomerulonephritis, vascular disease, allograft rejection, interstitial disease

Characterized by concentrated urine

Question 17

Post-renal AKI

Answer 17

Rare; usually occurs with obstruction that affects the kidneys bilaterally

Characteristic finding: several hours of anuria with flank pain, followed by polyuria

Question 18

CKD

Answer 18

Progressive loss of renal function commonly associated with systemic diseases such as DM (most significant), HTN, lupus, intrinsic kidney disease

Sodium and water alterations are NOT apparent until renal function declines <25% of normal

Ischemic renal injury leads to loss of nephrons, glomerular capillary HTN and increased angiotensin II, that results in increased glomerular permeability and filtration, proteinuria, hematuria, increased tubular protein reabsorption, inflammation, and renal fibrosis

Key factors:

1. Proteinuria (further promotes inflammation, fibrosis, anasarca)
2. Angiotensin II elevation (in attempt to increase GFR, causes glomerular and systemic HTN, hyperfiltration, proteinuria)

Clinical manifestations:

1. Azotemia (increased serum urea, creatine, and other nitrogenous compounds)
2. Uremia (increased serum urea and nitrogenous compounds)

S/S: Systemic HTN, anorexia, N/V/D or constipation, malnutrition, weight loss, pruritus, anasarca, anemia, neurologic and CV disease, skeletal changes

Question 19

Renal tumors

Answer 19

1. Renal clear cell (fat) carcinoma (most common; 80%): invades large vessels (travels hematogenously) and almost always sporadic; grade and stage are key prognostic indicators (poor in advanced stages)
2. Renal adenomas: uncommon, benign (can become malignant), solid, encapsulated, and located near renal cortex; treated with resection

Question 20

Bladder tumors

Answer 20

Urothelial (transitional cell) carcinomas: multifocal, unpredictable clinical course, and located in the inner bladder lining; low-grade or high-grade; high-grade that metastasizes via lymph nodes into detrusor muscle warrants cystectomy

Risk factors: Smoking, toxins (chemotherapy agents)

S/S: Painless hematuria