Nephrocalcinosis, once known as Albright's calcinosis after Fuller Albright, is a term originally used to describe the deposition of solubility calcium salts in the renal parenchyma due to hyperparathyroidism. The term nephrocalcinosis is used to describe the deposition of both calcium oxalate and calcium phosphate.
Signs and symptoms
Though this condition is usually
asymptomatic, if symptoms are present they are usually related to the causative process, (e.g.
hypercalcemia).
Some of the symptoms that can happen are
Hematuria, fever and chills, nausea and vomiting, severe pain in the belly area, flanks of the back, groin, or testicles.
These include renal colic, polyuria and polydipsia:
There are several causes of nephrocalcinosis that are typically acute and present only with kidney failure.
Cause
Nephrocalcinosis is connected with conditions that cause
hypercalcaemia, hyperphosphatemia, and the increased excretion of calcium, phosphate, and/or oxalate in the urine. A high urine pH can lead to nephrocalcinosis but only if it is accompanied by
hypercalciuria and hypocitraturia, since having a normal urinary
Citric acid usually inhibits the
crystallization of calcium. In conjunction with nephrocalcinosis, hypercalcaemia and hypercalciuria the following can occur:
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Primary hyperparathyroidism: Nephrocalcinosis is one of the most common symptoms of primary hyperparathyroidism.
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Sarcoidosis: Nephrocalcinosis is one of the most common symptoms.
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Vitamin D: This can cause nephrocalcinosis because of vitamin D therapy because it increases the absorption of ingested calcium and bone resorption, resulting in hypercalcaemia and hypercalciuria.
Medullary nephrocalcinosis
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Medullary sponge kidney
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Distal renal tubular acidosis
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]
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Hyperoxaluria
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]
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Renal papillary necrosis
And other causes of hypercalcaemia (and thus hypercalciuria)
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Immobilization (leading to hypercalcaemia and hypercalciuria)
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Milk-alkali syndrome
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Hypervitaminosis D
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Multiple myeloma
Hypercalciuria without hypercalcaemia
These conditions can cause nephrocalcinosis in association with hypercalciuria without hypercalcaemia:
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Distal renal tubular acidosis
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Medullary sponge kidney
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Neonatal nephrocalcinosis and loop diuretics
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Inherited tubulopathies
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Chronic hypokalemia
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Beta thalassemia
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Familial primary hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC)
Mechanism
Nephrocalcinosis is caused by an increase in the urinary excretion of
calcium,
phosphate, and/or
oxalate.
Nephrocalcinosis is closely associated with nephrolithiasis, and patients frequently present with both conditions, however there have been cases where one occurs without the other.
and calcium phosphate
form when the
concentration of the
reagent exceeds the limit of solubility of these compounds under the physiological conditions prevailing locally in the organism. The deposits are collected in the inner
Renal medulla in the basement membranes of the thin limbs of the loop of Henle.
The calcium phosphate plaques can enlarge into the surrounding interstitial tissue, or even rupture into the tubule lumen and can promote calcium oxalate stone formation.
Diagnosis
Nephrocalcinosis is diagnosed for the most part by imaging techniques. The imagings used are
ultrasound (US), abdominal plain film and
CT scan imaging.
Of the 3 techniques CT and US are the preferred modalities.
In some cases a renal biopsy is done instead if imaging is not enough to confirm nephrocalcinosis. Once the diagnosis is confirmed additional testing is needed to find the underlying cause because the underlying condition may require treatment for reasons independent of nephrocalcinosis.
Stages of nephrocalcinosis
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Chemical or Molecular nephrocalcinosis: Defined as a measurable increase in intracellular calcium concentrations, however, it is not visible through X-ray or microscopically.
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Microscopic nephrocalcinosis: Occurs when depositis are visible by light microscope by obtaining a tissue sample from a biopsy. However, this cannot be seen in an X-ray.
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Macroscopic nephrocalcinosis: Occurs when calcification can be seen through X-ray imaging.
Treatment
Increasing fluid intake to yield a urine output of greater than 2 liters a day can be advantageous for all patients with nephrocalcinosis. Patients with hypercalciuria can reduce calcium excretion by restricting animal protein, limiting
sodium intake to less than 100 meq a day and being lax of potassium intake. If changing one's diet alone does not result in a suitable reduction of hypercalciuria, a
Thiazide can be administered in patients who do not have hypercalcemia.
Citric acid can increase the solubility of calcium in urine and limit the development of nephrocalcinosis. Citrate is not given to patients who have urine pH equal to or greater than 7.
Prognosis
The prognosis of nephrocalcinosis is determined by the underlying cause. Most cases of nephrocalcinosis do not progress to end stage
Kidney disease, however if not treated it can lead to renal dysfunction this includes primary
hyperoxaluria,
Hypomagnesemia Hypercalciuria nephrocalcinosis and Dent's disease.
Once nephrocalcinosis is found, it is unlikely to be reversed, however, partial reversal has been reported in patients who have had successful treatment of hypercalciuria and hyperoxaluria following corrective intestinal surgery.
Recent research
In recent findings they have found that there is a genetic predisposition to nephrocalciosis, however the specific genetic and epigenetic factors are not clear. There seems to be multiple genetic factors that regulate the excretion of the different urinary risk factors. There has been some correlation seen that shows gene polymorphisms related to stone formation for calcium-sensing receptor and vitamin D receptors.
Repeated calcium stones associated with medullary sponge kidney may be related to an autosomal dominant mutation of a still unknown gene, however the genes is
GDNF seems to be a gene involved in renal morphogenesis.
In conjunction with the gene research is another theory of how the disease manifests. This is called the free particle theory. This theory says that the increasing concentration of lithogenic solutes along the segments of the nephron leads to the formation, growth, and collection of crystals that might get trapped in the tubular lumen and begin the process of stone formation.
Some of the backing behind this theory is the speed of
Crystal growth, the diameter of the segments of the
nephron, and the transit time in the nephron. All of these combined show more and more support for this theory.
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