| Discussion: The differential for hyperechoic medullary pyramids includes medullary nephrocalcinosis, protein deposition (e.g. Tamm-Horsfall protein), crystal deposition (e.g. sodium urate), autosomal recessive polycystic kidney disease, and dystrophic calcification (e.g. due to renal papillary necrosis).
The most common cause is medullary nephrocalcinosis. The differential includes hypercalcemic states (hyperparathyroidism, hypervitaminosis D, sarcoid, metastasis), hypercalciuric states (renal tubular acidosis, furosemide therapy), and medullary sponge kidney.
This particular patient has Bartter's syndrome. This is a renal tubular disorder which results in the inabilty to resord sodium at the loop of Henle. This autosomal recessive disorder leads to a hypokalemic metabolic alkalosis. The patients are hypocalcemic and hypercalciuric secondary to defective renal tubular transporters and an inappropriate ion gradient for calcium reabsorption. This leads to the medullary nephrocalcinosis demonstrated on ultrasound. |
BARTTER'S SYNDROME 
