Can Nephrocalcinosis and Kidney Stones Occur Together?
Yes, nephrocalcinosis and kidney stones frequently occur together and are commonly encountered as concurrent conditions in clinical practice. 1
Clinical Reality of Co-occurrence
Both nephrocalcinosis (calcium deposition within renal parenchyma) and nephrolithiasis (stone formation in calyces, renal pelvis, and bladder) can occur simultaneously in the same patient. 2 This co-occurrence is particularly common in specific disease states and metabolic conditions.
Common Underlying Conditions
The following conditions are frequently associated with both nephrocalcinosis and kidney stones occurring together:
Primary hyperoxaluria: Guidelines specifically recommend performing kidney ultrasound at least yearly to assess for the presence of both stones and nephrocalcinosis in these patients. 3 This reflects the expected concurrent presentation of both conditions.
Primary hyperparathyroidism: Endoscopic studies have demonstrated that the majority of calcifications seen on radiographs in these patients may actually be stones rather than pure tissue calcification. 4
Type I distal renal tubular acidosis: This condition commonly presents with both nephrocalcinosis and nephrolithiasis together. 4
Medullary sponge kidney: Another classic condition where both entities coexist. 4
Primary hypoparathyroidism: Studies show 6.7% of patients have nephrocalcinosis, with 5% having concurrent renal calculi. 5
Diagnostic Considerations
Important Caveat: Radiologic vs. Endoscopic Diagnosis
A critical pitfall is that distinguishing between nephrocalcinosis and nephrolithiasis on imaging alone is unreliable. 4 Non-contrast CT commonly shows calcifications in close association with renal papillae, but direct visual inspection via endoscopy is required for definitive diagnosis. 4 What appears as nephrocalcinosis on CT may actually be stones, and vice versa.
Screening Recommendations
In low-resource settings where genetic testing is unavailable, ultrasound and X-ray provide valuable information on the extent of both stone disease and nephrocalcinosis and should be performed in all patients suspected of having conditions predisposing to calcium deposition. 3
Pathophysiologic Link
Both conditions share common pathophysiology involving:
- Elevated urinary calcium levels (hypercalciuria) as a key pathological feature. 6
- Imbalance between inhibitors and promoters of crystallization. 7
- Supersaturation conditions along different nephron segments leading to crystal formation, growth, and aggregation. 7
The genetic and metabolic abnormalities that cause nephrocalcinosis often simultaneously create conditions favorable for stone formation, explaining their frequent co-occurrence. 8