Polycystic KD/Nephrolithiasis Flashcards
Polycystic Kidney Disease (PKD)
General
Autosomal condition characterized by fluid-filled sacs (cysts) in the kidneys that grow larger and lead to gradually loss of kidney function
Autosomal dominant (ADPDK) and recessive forms (ARPKD)
At least two genes account for the autosomal dominant disorder
ADPKD1 on the short arm of chromosome 16
Most common cause affecting 85-90% of patients
ADPKD2 on chromosome 4
Less common cause affecting 10-15% of patients
Slower progression of disease and longer life expectancy
PKD
Autosomal dominant inheritance pattern
The mutated gene is a dominant gene located on a non-sex chromosomes (autosomes)
Only one mutated gene is needed to be affected by this type of disorder
Signs and symptoms appear between 30-40 years of age
PKD
Autosomal recessive inheritance pattern
Two mutated genes, one from each parent is required
These disorders are usually passed on by two carriers (health is rarely affected)
Signs and symptoms can appear shortly after birth or into adolescence
PKD
Patho
Increasing number and size of cysts:
Compromise blood supply to the nephrons = poor perfusion to the kidney → What happens when there is poor perfusion?
Activation of the RAAS → fluid retention & ↑ BP
Compression of the collecting system → urinary stasis and the possibility of kidney stone formation
Destruction of the normal renal architecture → flank pain and hematuria
PKD
Clin Man
Renal Manifestations
Abdominal pain or flank pain
Microscopic or gross hematuria
Hypertension
Abdominal mass (enlarged kidneys that are palpable on exam)
PKD
Complications
Poorly controlled hypertension
Loss of kidney function- ESRD develops by age 60 years in 50% of patients
Nephrolithiasis: 20% of patients
Stones are usually made of calcium oxalate
Renal Infection: Cysts can become infected
Flank pain, fever, leukocytosis
Urinalysis can be normal if the cyst does not communicate with the urinary tract
Development of a cerebral aneurysm (Berry aneurysm)
10-15% of patient have an aneurysm in the circle of Willis
Pregnancy complications
Associated with higher risk for preeclampsia
PKD
Family Hx
Known family history
Diagnostic criteria for autosomal dominant polycystic kidney disease:
Two or more cysts in patients 30 or younger
Two or more cysts in each kidney in patients 30-59 years
Four or more cysts in each kidney in patients 60 years or older
No known family history
CT scan of the abdomen and pelvis to establish the presence of cysts in the kidney(s) and possibly the liver
Genetic testing for the ADPKD1 or ADPKD2 mutations
Don’t memorize
PKD
Imaging
Ultrasound
Performed to detect the size and number of kidney cysts
CT scan or MRI
Performed if ultrasound findings are inconclusive
Can detectcysts of smaller size
Determines total kidney volume (helps assess the risk of kidney disease progression)
PKD
Management of blood pressure
Use of an angiotensin-converting enzyme (ACE) or angiotensin II receptor blockers (ARB)
Target BP of < 110/75 mmHg in young, healthy individuals aged 18 to 50 years with normal GFR
Target BP of < 130/80 mmHg in all other patients
PKD
Lifestyle Mods
Dietary sodium restriction
2 grams intake per day or less
Increase fluid intake
Drink > 3 L of fluid per day, unless the eGFR is < 30 or the patient is at risk for hyponatremia (taking a thiazide diuretic)
Suppress plasma vasopressin (antidiuretic hormone (ADH)) levels
Limit alcohol use
OTC acetaminophen for chronic pain; avoid use of NSAIDs
PKD
End-stage renal disease (ESRD)
~half ofpatients ≥ 75 years of age
Hemodialysis orperitoneal dialysis
Kidney transplantation
Nephrolithiasis/ Urolithiasis
General
One of the most common conditions affecting the urinary system
Formation of a stone (calculus) anywhere along the urinary tract
Caused by the precipitation of solutes (minerals and salts) in the urine
Most common stone composition:
Calcium oxalate 70-80%
Struvite (ammonium magnesium phosphate) 5-10%
Uric acid 10%
Cystine < 5%
Calcium phosphate 5%
Most common in non-Hispanic white patients; least common in black and Asian patients
Incidence increases with age
19% of men and 9% of women will be diagnosed with a kidney stone by age 70
Nephrolithiasis/ Urolithiasis
RF
Family history
Urinary factors
pH
Alkaline urine (≥ 6.5) → calcium phosphate stones
Acidic urine (≤ 5.5) → uric acid stones
Volume
Higher urine volume is associated with a lower risk
Dietary factors
Higher consumption of animal protein and lower intake of fruits and vegetables → decreased urine pH (uric acid stones)
Sugar-sweetened beverages
High serum and urine calcium
Dehydration
Excessive concentration of urine solutes → stone formation
Loop diuretics
Inhibits calcium reabsorption → hypercalcinuria
Also has an inhibitory effect of sodium and potassium
Examples: furosemide (Lasix) and bumetanide (Bumex)
Nephrolithiasis
Kidney Stones
All stones are radiopaque except uric acid stones
Calcium oxalate, uric acid, and calcium phosphate are non-infection stones
Struvite are infection stones
Cystine stone is a genetic stone; autosomal recessive defect insodium-dibasicamino acidcotransporter
Nephrolithiasis
Staghorn calculi
Also referred to as coral calculi
Usually a struvite stone
Branched stones that occupy a large portion of the collecting system (renal pelvis and calyces)
Can damage the kidney and/or lead to life threatening urosepsis
Nephrolithiasis
Medical Conditions Associated with Kidney Stones
Primary hyperparathyroidism (high calcium levels)
Gout (high uric acid)
Hypertension
Diabetes mellitus
Obesity
Inflammatory bowel disease (IBD)
Short gut syndrome
Gastrointestinal bypass surgery
Urinary tract infections (chronic upper urinary tract)
Nephrolithiasis
Clin Man
Depends on the size, number, and location of the stone(s)
Small stones may be asymptomatic
Pain (renal colic)
Most common symptom and can be variable
Waxes and wanes in severity and develops in waves
Develops when stones initially pass into the ureter causing ureteral obstruction
Site of obstruction determines the location of pain
Upper ureteral or renal pelvis obstruction = flank pain/costovertebral angle (CVA) tenderness
Lower ureteral obstruction = radiates to the labium or ipsilateral testicle
Variable location of pain can be misleading and can mimic an acute abdomen or dissecting aneurysm
Hematuria
Gross or microscopic → trauma to the ureter
Discriminating predictor of a kidney stone in patients with unilateral flank pain
Other symptoms:
Nausea and/or vomiting
Dysuria and urinary urgency
Fever → infection
Nephrolithiasis
Sites of Obstruction
Kidney stones can lodge in any of the 3 natural narrowings along the ureter:
Ureteropelvic junction(UPJ)
Junction of therenal pelvisand ureter
Ureter at thepelvic inlet
Site of ureteral crossing of the iliac vessels
Ureterovesical junction (UVJ)
Junction of the ureter andurinary bladder
Nephrolithaisis
Complications of Obstruction
A lodged stone can cause obstruction and consequent proximal complications:
Acute pyelonephritis:
Obstruction of theurinary tract, which allows for proximal overgrowth ofbacteria
Inflammationof therenal pelvis → kidney parenchyma results
Presents withfever, urinary frequency, urgency,dysuria, and costovertebral angle tenderness
Hydronephrosis:
Obstruction causes proximal accumulation ofurine
Results in the dilation of therenal pelvis and calyces (visible on imaging)
Nephrolithiasis
Labs
Nephrolithiasis should be suspected in patients with renal colic or flank pain with or without gross hematuria
Labs
BMP
Assess kidney function (BUN and creatinine)
Urine pregnancy test
Urinalysis
To evaluate for hematuria and signs of urinary tract infection
Pyuria and positive nitrites – concurrent urinary tract infection
Urine microscopic
Evaluates for the presence and shape of crystals
Nephrolithiaisis
Imaging
Diagnostic imaging
Determines if a kidney stone is present and to assess for obstruction (hydronephrosis)
Stone size and location
Helps to predict the likelihood of spontaneous passage
Guide management
Recent passage of a ureteral stone can also be seen:
Pyeloureteral dilatation
Perinephric stranding
Modalities
CT scan of the abdomen and pelvis without contrast (gold standard)
IV contrast can decrease sensitivity for small stones (> 2 mm)
If a patient is pregnant, an ultrasound of the kidneys and bladder is preferred
Abdominal x-ray (KUB): can detect large stones
Nephrolithiasis
tx
Many patients can be managed with hydration (reverses precipitation) and pain management until the stone passes (≤ 5 mm)
Hospitalization for patients that:
Cannot tolerate oral intake
Have uncontrolled pain or fever
Strain urine
Done for several days to capture the stone for analysis
Urology consultation
Patients with concomitant urinary tract infection
Obtain a urine culture
Prompt treatment with antibiotics
Acute kidney injury
Anuria
Bilateral ureteral obstruction
Single-functioning kidney
Nephrolithiasis
Pain control
NSAIDs
Initial choice for pain control
Ketorolac (Toradol) 15-30 mg IV
Relief in 10-30 minutes
Opioids
Stone passage
Smaller and more distal stones are more likely to pass without intervention
≤ 5 mm pass spontaneously
≥ 10 will not pass
Alpha adrenergic blocker
Ureteral stones > 5 mm and < 10 mm
Tamsulosin (Flomax) 0.4 mg PO once daily for up to 4 weeks
Nephrolithiasis
Surgical management
Indications
10-20% of all kidney stones require surgical removal
Indications:
Pain
Infection
Urinary obstruction
Surgical options
Ureteroscopy (with stent)
Treatment of choice for the majority of middle and distal ureteral stones; can also be used to manage proximal ureteral stones
Modality of choice for patients with obesity, who are pregnant, or have a bleeding disorder
Stents are sometimes placed to help prevent ureteric obstruction and pain from passage of a stone
Stents can be uncomfortable and patient are more likely to have lower urinary tract symptoms (dysuria, frequency, urgency and hematuria)
Shock wave lithotripsy
Shock wave lithotripsy
High-intensity acoustic pulses
Not suitable for patients with obesity, pregnant patients, patients with uncontrolled bleeding disorders, or patients with abnormal anatomy
Percutaneous nephrolithotomy
Surgical procedure with skin incision to retrieve the kidney stone
Reserved for large (> 20 mm) or complex stones (Staghorn stones)
Stone-Specific Management
Calcium oxalate and calcium phosphate stones
Low-sodium diet to increase concomitantsodium andcalcium reabsorptionin proximal tubules
Citrate to dissolvecalcium oxalate crystals
Thiazide diuretics to increasecalcium reabsorption in the distal tubule
Stone-Specific Management
Struvite stones
Antibiotic therapy to eliminate the causative microbe
Proteus mirabilis
Proteus vulgaris
Morganella morganii
Stone-Specific Management
Uric acid stones
Urine alkalinization withpotassium citrate to dissolve uric acid crystals
Allopurinol to decrease uric acid production
