Medullary Nephrocalcinosis

Case history: A 27-year-old pregnant patient with history of renal colic. Ultrasound showed increased echogenicity of renal pyramids. Both kidneys showed a small calculus both sides.

 Figures 1 and 2: Increased echogenicity of renal pyramids

Figure 2

Figures 3 and 4: b/l renal calculi

 Figure 4

Diagnosis: Medullary nephrocalcinosis. Further evaluation showed primary hyperthyroidism.

Discussion: Nephrocalcinosis, once known as Albright's calcinosis after Fuller Albright, is a term originally used to describe deposition of calcium salts in the renal parenchyma due to hyperparathyroidism. It is now more commonly used to describe diffuse, fine, renal parenchymal calcification on radiology. During its early stages, nephrocalcinosis is visible on X-ray, and appears as a fine granular mottling over the renal outlines. These outlines eventually come together to form a dense mass. It is most commonly seen as an incidental finding with medullary sponge kidney on an abdominal X-ray. However, it may be severe enough to cause (as well as be caused by) renal tubular acidosis or even end stage renal failure, due to disruption of the renal tissue by the deposited calcium.

Stages of nephrocalcinosis: Chemical, microscopic, and macroscopic nephrocalcinosis.

Symptoms of nephrocalcinosis: Though this condition is usually asymptomatic, if symptoms are present they are usually related to the causative process, (e.g. hypercalcemia). These include renal colic, polyuria and polydipsia.

Renal colic is usually caused by pre-existing nephrolithiasis, as may occur in patients with chronic hypercalciuria. Less commonly, it can result from calcified bodies moving into the calyceal system. Nocturia, polyuria, and polydipsia from reduced urinary concentrating capacity (i.e. nephrogenic diabetes insipidus) as can be seen in hypercalcemia, medullary nephrocalcinosis of any cause, or in children with Bartter syndrome in whom essential tubular salt reabsorption is compromised.

There are several causes of nephrocalcinosis that are typically acute and present only with renal failure. These include tumor lysis syndrome, acute phosphate nephropathy, and occasional cases of enteric hyperoxaluria.

Harpreet Singh, MD
JP Scan private diagnostic center, Khanna, Punjab, India