Renal Bx, Renal Stones

Question 1

Indications NOT to do a Biopsy

Answer 1

1. Isolated Glomerular Haematuria
   - asymptomatic microscopic haematuria, negative proteinuria, normal serum creatinine
2. Isolated non-nephrotic proteinuria
3. Known conditions

Question 2

Indications to DO a Biopsy

Answer 2

1. AIN
2. Nephrotic syndrome
   - unknown cause ie no apparent underlying disease
3. SLE
4. Acute nephritic syndrom
   - haematuria, cecllular casts, proteinuria, renal insufficiency, HTN
5. GN a/w Hep C or B or other +ve cultures/fungi/parasites/bacterial abscesses

Question 3

Contraindications to a Renal Biopsy

Answer 3

Relative

• Small hyperechoic kidneys (less than 9 cm), which are generally indicative of chronic irreversible disease
• Solitary native kidney (can perform an open renal bx instead)
• Multiple, bilateral cysts or a renal tumor
• Uncorrectable bleeding diathesis
• Severe hypertension that cannot be controlled with antihypertensive medications
• Hydronephrosis
• Active renal or perirenal infection
• Anatomic abnormalities of the kidney that may increase risk (see above)
• Skin infection over the biopsy site

Question 4

Complications of Bx

Answer 4

1. Bleeding/hematoma
   - seen in 12-24 hours, p/w renal capsular pain. RF - HTN, High Cr, Age >40
2. Pain
3. AV Fistula
4. Page kidney
   - very rare, haematoma causes pressure-induces ischaemia, activation of RAAS and HTN

Question 5

Renal Stones

RF

Answer 5

A. urine calcium, food intake - animal protein, sodium, low fluid intake, low potassium intake, high Vit C (in men)

B. Famuly history or past history

C. Malabsorbtion

D. Frequent upper UTI (usually due to spinal cord injuries)

E. Medications - acyclovir, triamterene, indinavir ?cef

F. Comorbidities - gout, DM, obesity, HTN

G. Excersive exercise
Urease-producing organism - Proteus/Klebsiella (Struvite stone)

Question 6

Renal Stone Types

Answer 6

-Usually calcium stones (80%) - made up of calcium oxalate or less often, calcium phosphate

Struvite stones

Question 7

Struvite stones

Answer 7

• large - can have stag horn calculus
• composed of Magnesium ammonium phosphate + calcium carbonate
• Due to UTI caused by urease producing organisum
• Klebsiella, Proteus

Question 8

Urine dipstick

Answer 8

Protein - only detects albumin

Nitrites - from some nitrate producing bacteria

WCC - may not detect in concentrated urine

Blood - false positive with Vit C or semen