RADIOLOGY: KIDNEY: Case# 33653: MEDULLARY NEPHROCALCINOSIS SECONDARY TO RENAL TUBULAR ACIDOSIS. 4 year old female with a history of renal tubular acidosis. Both kidneys reveal multiple areas of increased echogenicity involving all the renal pyramids. The renal cortex is normal and there is no evidence of hydronephrosis. Medullary nephrocalcinosis is usually associated with hypercalcemic states. Hyperparathyroidism and distal renal tubular acidosis accounts for >60% of cases. The remaining 40% are due to a variety of other causes of hypercalcemia and hypercalciuria such as Cushing syndrome, sarcoidosis, bone metastasis, lasix therapy and vitamin supplementation.