Renal Ultrasound - Cortical Nephrocalcinosis
Figure 1. Kidney model depicting renal medulla ("pyramids") and cortex with interpyramidal renal columns ("columns of Bertin").
Macroscopic nephrocalcinosis - the detection of calcium deposits on radiological imaging - can be divided into cortical and medullary forms.
Cortical nephrocalcinosis is quite rare, accounting for less than 3% of all cases of nephrocalcinosis (1).
Commonly cited causes include (1-3):
- Renal cortical necrosis
- Chronic glomerulonephritis
- Alport syndrome (Fig. 2-4)
- Oxalosis
Figure 2. Cortical nephrocalcinosis in a patient with Alport syndrome. The renal cortex displays an intensely hyperechogenic outer rim, which extends into the renal columns. (see captions in Figure 4)
Figure 3. Diffuse "twinkling" of the hyperechogenic rim.
Figure 4. Detail of Figure 2. Surface of the kidney marked by red line, pyramids shaded blue. Red arrows highlight hyperechogenic renal columns.
The mechanisms of calcium deposition in cortical nephrocalcinosis are not well studied, if at all. Most cases are probably the result of dystrophic calcifications (i.e. due to local tissue abnormalities). Occasionally, disorders of calcium metabolism may also play a role (1).
References
- Wrong O. Nephrocalcinosis. In: Oxford textbook of clinical nephrology. 2nd ed. Cameron S, Davison AM, eds. Oxford: Oxford University Press; October 9, 1997.
- Schepens D, Verswijvel G, Kuypers D, Vanrenterghem Y. Renal cortical nephrocalcinosis. Nephrology Dialysis Transplantation. 2000;15(7):1080–1082. doi:10.1093/ndt/15.7.1080.
- Zagoria RJ. Genitourinary Radiology: The requisites. 2nd ed. United States: Elsevier Health Sciences; June 4, 2004.