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Renal stones: risk factors
Risk factors
dehydration
hypercalciuria, hyperparathyroidism, hypercalcaemia
cystinuria
high dietary oxalate
renal tubular acidosis
medullary sponge kidney, polycystic kidney disease
beryllium or cadmium exposure
Risk factors for urate stones
gout
ileostomy: loss of bicarbonate and fluid results in acidic urine, causing the precipitation of uric acid
Drug causes
drugs that promote calcium stones: loop diuretics, steroids, acetazolamide, theophylline
thiazides can prevent calcium stones (increase distal tubular calcium resorption)
7 4-The albumin:creatinine excretion ratio (ACR) may be used to quantify the degree of proteinuria in renal disease. A normal ACR may be defined as:
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A.
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2.5 - 5
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B.
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< 0.25
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C.
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< 2.5
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D.
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5 - 50
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E.
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< 25
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ProteinuriaMicroalbuminuria
defined as an albumin excretion of 30 - 300 mg/day Albumin:creatinine excretion ratio (ACR)
used in clinical practice to quantify degree of proteinuria
first morning urine sample
urine albumin (mg) / creatinine (mmol)
normal ACR < 2.5
microalbuminuric range = 2.5 - 33
Which one of the following causes of glomerulonephritis is associated with low complement levels?
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A.
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IgA nephropathy
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B.
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Membranous glomerulonephritis
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C.
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Minimal change disease
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D.
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Post-streptococcal glomerulonephritis
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E.
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Focal segmental glomerulosclerosis
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Glomerulonephritis and low complement
Disorders associated with glomerulonephritis and low serum complement levels
post-streptococcal glomerulonephritis
subacute bacterial endocarditis
systemic lupus erythematous
mesangiocapillary glomerulonephritis
Which of the following types of renal stones are radio-lucent?
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A.
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Triple phosphate stones
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B.
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Cystine stones
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C.
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Calcium phosphate
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D.
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Xanthine stones
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E.
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Calcium oxalate
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Renal stones on x-ray
cystine stones: semi-opaque
urate + xanthine stones: radio-lucent
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Renal stones: imaging
The table below summarises the appearance of different types of renal stone on x-ray
Type
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Frequency
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Radiograph appearance
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Calcium oxalate
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40%
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Opaque
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Mixed calcium oxalate/phosphate stones
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25%
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Opaque
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Triple phosphate stones
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10%
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Opaque
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Calcium phosphate
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10%
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Opaque
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Urate stones
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5-10%
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Radio-lucent
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Cystine stones
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1%
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Semi-opaque, 'ground- glass' appearance
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Xanthine stones
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<1%
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Radio-lucent
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7 7-Which of the following types of renal tubular acidosis is most likely to cause osteomalacia?
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A.
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Type 1 renal tubular acidosis
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B.
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Type 2 renal tubular acidosis
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C.
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Type 3 renal tubular acidosis
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D.
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Type 4 renal tubular acidosis
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E.
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Type 5 renal tubular acidosis
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Renal tubular acidosis
All three types of renal tubular acidosis (RTA) are associated with hyperchloraemic metabolic acidosis (normal anion gap)
Type 1 RTA (distal)
inability to generate acid urine (secrete H+) in distal tubule
causes hypokalaemia
complications include nephrocalcinosis and renal stones
causes include idiopathic, RA, SLE, Sjogren's Type 2 RTA (proximal)
decreased HCO3- reabsorption in proximal tubule
causes hypokalaemia
complications include osteomalacia
causes include idiopathic, as part of Fanconi syndrome, Wilson's disease, cystinosis, outdated tetracyclines
Type 4 RTA (hyperkalaemic)
causes hyperkalaemia
causes include hypoaldosteronism, diabetes
Which one of the following is least recognised as an indication for plasma exchange?
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A.
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Myasthenia gravis
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B.
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Goodpasture's syndrome
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C.
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Multiple sclerosis
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D.
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Churg-Strauss syndrome
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E.
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Cryoglobulinaemia
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Plasma exchange
Indications for plasma exchange
Guillain-Barre syndrome
myasthenia gravis
Goodpasture's syndrome
ANCA positive vasculitis e.g. Wegener's, Churg-Strauss
TTP/HUS
cryoglobulinaemia
hyperviscosity syndrome e.g. secondary to myeloma
7 9-Which of the following factors would suggest that a patient has pre-renal uraemia rather than established acute tubular necrosis?
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A.
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Urine sodium = 70 mmol/L
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B.
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Fractional urea excretion = 20%
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C.
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No response to fluid challenge
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D.
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Urine:plasma urea ratio 5:1
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E.
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Specific gravity = 1005
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ATN or prerenal uraemia? In prerenal uraemia think of the kidneys holding on to sodium to preserve volume
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ARF: ATN vs. prerenal uraemia
Prerenal uraemia - kidneys hold on to sodium to preserve volume
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Pre-renal uraemia
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Acute tubular necrosis
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Urine sodium
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< 20 mmol/L
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> 30 mmol/L
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Fractional sodium excretion*
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< 1%
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> 1%
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Fractional urea excretion**
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< 35%
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>35%
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Urine:plasma osmolality
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> 1.5
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< 1.1
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Urine:plasma urea
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> 10:1
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< 8:1
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Specific gravity
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> 1020
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< 1010
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Urine
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'bland' sediment
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brown granular casts
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Response to fluid challenge
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Yes
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No
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*fractional sodium excretion = (urine sodium/plasma sodium) / (urine creatinine/plasma creatinine) x 100
**fractional urea excretion = (urine urea /blood urea ) / (urine creatinine/plasma creatinine) x 100
8 0-Autosomal dominant polycystic kidney disease type 2 is associated with a gene defect in:
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A.
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Chromosome 4
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B.
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Chromosome 8
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C.
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Chromosome 12
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D.
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Chromosome 16
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E.
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Chromosome 20
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ADPKD type 2 = chromosome 4 = 15% of cases
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ADPKD
Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited cause of kidney disease, affecting 1 in 1,000 Caucasians. Two disease loci have been identified, PKD1 and PKD2, which code for polycystin-1 and polycystin-2 respectively
ADPKD type 1
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ADPKD type 2
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85% of cases
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15% of cases
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Chromosome 16
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Chromosome 4
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Presents with ESRF earlier
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The screening investigation for relatives is abdominal ultrasound: Ultrasound diagnostic criteria (in patients with positive family history)
two cysts, unilateral or bilateral, if aged < 30 years
two cysts in both kidneys if aged 30-59 years
four cysts in both kidneys if aged > 60 years
8 1-A patient with type 1 diabetes mellitus is reviewed in the nephrology outpatient clinic. He is known to have stage 2 diabetic nephropathy. Which of the following best describes his degree of renal involvement?
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A.
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Microalbuminuria
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B.
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End-stage renal failure
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C.
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Latent phase
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D.
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Hyperfiltration
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E.
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Overt nephropathy
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