Nephrocalcinosis
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Transcript of Nephrocalcinosis
NEPHROCALCINOSIS
DM SEMINARDr. Vishal Golay
23/02/2011
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TOPIC OVERVIEW
Types of Nephrocalcinosis Causes Pathogenesis Diagnostic work up Treatment
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INTRODUCTION
The true incidence of nephrocalcinosis is difficult to establish due to the wide range of etiologies.
Data available from case collections› Mortensen and Emmett-91 cases (1954) J Urol 71:398–406
› Monserrat et al -77 cases (1979)
› Wrong and Feest-375 cases (1976) Advanced medicine no 12. Pitman Medical, London, pp 394–206
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INTRODUCTION
The term means an increase in the calcium content (generalized) of the kidney parenchyma.
Three forms:› Chemical Nephrocalcinosis› Microscopic Nephrocalcinosis› Macroscopic Nephrocalcinosis
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Hypercalcemic Nephropathy
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Hypercalcemic Nephropathy
Renal vasocontriction Loss of concentrating capacity and
resistance to vasopressin Alkalosis/acidosis K and Mg loss Hypertension
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Microscopic Nephrocalcinosis
Precipitation of Ca as phosphate or oxalate
Midway in spectrum b/w Hypercalcemia and macroscopic nephrocalcinosis.
Healthy kidneys contain Ca on autopsy. Many times diagnosis is made
biochemically
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Macroscopic Nephrocalcinosis
The calcium deposits are visualized by imaging techniques.
Conventional X-ray, USG, CT and MRI can be used.
Can affect the cortex as well as the medulla depending on the etiology
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Etiology
Cortical Nephrocalcinosis (2.4% of all cases)› Chronic Glomerulonephritis› Acute Cortical Necrosis› Chronic Pyelonephritis› Benign Nodular subcapsular type› Post transplant› Post traumatic› Oxalosis
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Etiology
Medullary Nephrocalcinosis (97.6% of all cases)› Conditions causing hypercalcemia› Idiopathic Hypercalciuria› Oxalosis› dRTA› MSK› Renal papillary necrosis› Dent’s disease› Other rare causes
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Pathogenesis
There are two types of microscopic crystal deposition-
› One taking place within the tubular lumen (intratubular nephrocalcinosis), and
› the other in the interstitium (interstitial nephrocalcinosis).
Nephrol Dial Transplant (2009) 24: 2030–2035
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Intratubular nephrocalcinosis
Two main pathogenetic processes are involved supersaturation Crystal formation failure of anti-crystal forming controls.
epithelial crystal adhesion
Crystal retention tubular crystal obstruction
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Intratubular nephrocalcinosis
Consequences: Crystal obstruction cause damage due to the
decrease in no. of functioning nephrons acutely and secondarily due to the chronic changes caused by it.
It can also lead to nephrolithiasis Crystal adhesion cause slow damage,
hampers redifferentiation/regeneration of functioning tubules and also can form nidus for growth of other crystals
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Interstitial Nephrocalcinosis
Mechanisms of formation: Transcytosis
Exocytosis Exotubulosis
De novo formation Randall’s plaque
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Mechanisms involved in renal crystal handling and the development of nephrocalcinosis
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Some important causes of nephrocalcinosis
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Hypercalcemia
Primary hyperparathyroidism is the most important cause (in adults) according to all the series.
Medullary location. More closely related to the duration of
hypercalcemia rather than the severity. Degree of renal failure does not
correlate with nephrocalcinosis.
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Distal RTA
Nephrocalinosis is an important manifestation of dRTA although any condition causing NC can lead to dRTA.
Factors leading to stone formation in dRTA:› Hypercalciuria› Hypocitraturia› Alkaline urinary pH
Predominant crystal deposited is Calcium PO4
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Medullary Sponge Kiney
Ectatic dilatation of the distal collecting tubules confined to the renal pyramids
Not exactly a true NC as the calcium deposition lies in the dilated tubules.
70% of the concretions is Calcium PO4 Relatively benign condition. Diagnosis by radiology
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Clinical implications of NC
Features of the underlying primary condition.
Renal stone formation. UTI Polyuria and thirst (decreased
concentrating capacity). Renal Failure. Hypertension is not a usual feature.
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Clinical implications
Sterile pyuria (uniform finding). Erythrocytosis. Proteinuria is also not marked(except in
Dent’s disease and Fanconi syndrome). Impairment in urinary acidification
(makes the diagnosis of dRTA difficult).
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Natural History
Nephrocalcinosis generally persists for life with a few exceptions.
Barring a few exceptions the majority of the causes are incurable.
Many of the conditions can lead to development of renal failure.
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Natural History
Probability of development of ESRD in various diseases causing NC:
Best: 1. Idiopathic hypercalciuria 2. MSK 3. dRTA 4. Hypercalcemic conditions 5. Papillary Necrosis 6. Dent’s Disease 7. Hypomagnesemia-hypercalcemia syndrome
Worst: Primary Hyperoxaluria type 1
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Evaluation
Proper history and examination
Laboratory investigations:› RFT, Ca profile› Urinalysis› Urine c/s› 24 hour timed urine examination› iPTH, TSH› Urinary Magnesium Levels
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Evaluation (Radiological Investigations)
Overview: Forms the basis of diagnosis. May detect asymptomatic cases. CT scan is the most sensitive and
specific test but carries radiation risk. USG has inter-observer variation. Conventional radiography cannot
detect NC until attenuation exceeds 100HU
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X-Ray KUB
Requires attenuation values above 100HU
<2mm deposits are rarely picked up. the spatial resolution of the recording
technique, and contrast factors also influence the detection rate.
Useful as a screening tool
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X-Ray KUB
Cortical Nephrocalcinosis:› Single cortical, calcified, thin peripheral
band, often with calcified extensions into the necrotic septa of Bertin.
› Hyperattenuating tram lines (more commonly interrupted s/o patchiness of CAN)
› Punctate calcification (CGN)
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X-Ray KUB
Medullary Nephrocalcinosis
Appears as clusters of stippled calcifications, mainly within the regions of the renal pyramids.
Many of the disease causing medullary NC also causes nephrolithiasis which can be seen
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Pyramidal calcification in right upper pole
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Spiral CT Scan
Most sensitive modality. Can pick up diseases at an earlier
stage, and better information about the extent of disease.
Also picks up other findings eg. Cysts Use of contrast to d/f between stones
and true NC, and also for MSK Radiation is an issue (10 times more
than KUB X-ray)
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USG
Can pick up NC even at an earlier stage than by X-ray.
In medullay ND the pryamids are visualized as rounded or echogenic structures. Shadowing can also be seen.
In cortical NC, increased cortical echogenicity and shadowing in severe cases. Secondary pyramidal fibrosis with increased echotexture can be seen.
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Treatment
Hypercalcemic nephropathy: Supportive treatment of the hypercalcemia and treatment of the underlying etiology
For the other causes treatment of the underlying cause forms the only possible care
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Treatment (some examples)
Thiazide diuretics and dietary salt restriction
Potassium and Mg supplementation Citrate supplementation-increases
urinary citrate and decreases Ca excretion (useful in dRTA and idiopathic hypercalciuria)
Magnesium supplementation in Mg losing disorders
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Treatment (some examples)
Pyridoxine in Type1 hyperoxaluria. Oral calcium supplementation, low fat
diet and cholestyramine in hyperoxaluria to decrease intestinal absorption
Alkali supplementation in dRTA Surgical attempts at removing the
nodules of NC can cause further destruction and should be avoided
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