Flashcards in Hematuria and Nephrolithiasis Deck (37)
Is a positive dipstick test for hematuria confirmatory for blood?
No. A further microscopic confirmation is required.
What are the imposters of hematuria?
• Free hemoglobinuria
• Menstrual contamination
Can hematuria be caused by anticoagulant therapy?
Not usually - only when there is massive overdose
What is the definition of microscopic hematuria?
≥ 2 RBC’s/hpf
What are some sequelae of gross hematuria?
- Acute urinary retention due to clot formation
- Anemia from pronounced loss
What is gross hematuria often associated with?
What are the main glomerular causes of microscopic hematuria in those below 50 years old?
Thin Basement Membrane Disease
Mild Focal GN
What are the main glomerular causes of microscopic hematuria in those above 50 years old?
Mild Focal GN
What are some of the risk factors of urologic cancer?
• Cigarette smoking
• Occupational exposures: Leather, dye, rubber/tire manufacturing industries
• Phenacetin use (analgesic)
• Aristolochic acid use (herbal diet agent)
What features suggest glomerular hematuria?
• RBC casts
• Dysmorphic RBC’s, acanthocytes
• Proteinuria (ratio > 0.3 or >300mg/day)
• Elevated renal indices (BUN, Creatinine)
What features suggest non-glomerular hematuria?
• Isomorphic RBC’s
• No proteinuria
• Normal renal indices
What is a major technique used for the management of gross hematuria?
Large bore Foley catheterization
What is the typical patient with kidney stones in NA?
What time of the year is the rate of kidney stones the highest?
In the summer
What is the presentation with a stone in the upper ureter?
• Flank pain, upper anterior abdominal pain
What is the presentation with a stone in the lower ureter?
• Groin pain, ipsilateral testicular/labial pain
What is the composition of most kidney stones?
What are the other possibilities for the composition of kidney stones?
• 10-15% Uric acid
• 10-15% Magnesium ammonium phosphate a.k.a. Struvite
How does kidney stone formation occur?
Stone formation starts with supersaturation with nucleation as the key phase
What factors can promote stone formation?
• Increased urinary ion excretion
• Decreased urine volume
What compounds are promoters of stone formation?
Hydrogen ions (low pH), sodium, magnesium, uric acid
What substances prevent stone formation?
What is the major cause of nephrolithiasis?
What is the most common cause of hypercalciuria?
Idiopathic - familial
What are some other causes of hypercalciuria?
• Vitamin D excess
• Sarcoidosis (D3 production in granulomas)
• Glucocorticoid excess
What is the interaction of Ca2+ and oxalate in the GI tract?
• Dietary calcium binds with oxalate and impedes absorption
• Any unbound oxalate absorbed in colon
What happens to absorbed oxalate?
• Absorbed oxalate excreted
• Excreted oxalate binds to urinary calcium
• Can lead to stone formation
How does low dietary Ca lead to kidney stones?
Low dietary Ca means that oxalate is more easily absorbed unimpeded to be excreted in the kidney which leads to increased stone formation
What are the causes of uric acid stones?
• Chronic metabolic acidosis
• Low urinary pH (
What causes the formation of struvite stones?
Bacterial infection. Main cause is Proteus mirabilis
How do struvite stones affect the urine?
Results in ammonia and persistently alkaline urine, promotes struvite formation
What is the cause of cystine stones?
Cystinuria - autosomal recessive disorder that is rare
What is the preferred imaging method for kidney stones?
CT scan without contrast preferred
In what situations is medical management of kidney stones reasonable?
• Small stones (less than 5 mm)
• Distal ureteral location
• Adequate pain control with analgesics
• No associated UTI or localized obstruction
In what situations is interventional management of kidney stones reasonable?
• Larger stones (>6mm), especially proximal
• Not passing after 4 weeks of medical therapy
• Intractable pain
• Associated UTI or localized obstruction
What is done to prevent future Ca2+ stones?
• Low sodium, low animal protein diet
• NORMAL dietary calcium
• Medication: thiazide diuretic