Hyperechoic Renal Medulla

Hyperechoic renal medulla may be seen with the following conditions:

• Dehydration/Sepsis
• Medullary nephrocalcinosis:
  • Hypercalcemia:
    • Hyperparathyroidism: Primary or secondary
    • Bone destruction/turnover: Metastatic disease, Paget, osteoporosis, immobilization (especially, especially in infants)
    • Medications: Milk-alkali syndrome (ingestion of lots of calcium), hypervitaminosis D, furosemide (especially in children).
  • Renal tubular acidosis: Type 1 (distal).
  • Medullary sponge kidney (image shown above): Tiny calculi in dilated tubules. Usually asymptomatic, but may be complicated by nephrolithiasis, denal calculi, and urinary tract infection.
    
    
  • Sarcoidosis:
  • Syndromes: Williams, Hurler, Bartter, Achondroplasia.
• Renal papillary necrosis: Multifactorial process. Most common causes are pyelonephritis, analgesic nephropathy, and diabetes. Trivia: Beethoven's autopsy revealed renal papillary necrosis, possibly due to his alcohol and analgesic abuse, cirrhosis, and diabetes.

There's a stupid mnemonic for medullary nephrocalinosis that, like all such mnemonics, is 1) too long to be of any use, and 2) sacrifices relevance for the sake of the acronym. It is repeated here for the sake of completeness: Stadiumm Ditch (Sarcoidosis, Tuberculosis, A (vitamin), D (vitamin), Immobilization, Milk-alkali syndrome, Medullary sponge kidney, diuretics (furosemide in children), Idiopathic (especially in neonates/infants with Williams syndrome), Thyrotoxicosis, Carcinoma, Hyperparathyroidism).

Papillary necrosis also has a mnemonic, Postcards: Pyelonephritis, Obstruction of the urinary tract, Sickle cell, Tuberculosis, Cirrhosis of the liver, Alcoholism, Analgesic abuse, Renal transplant rejection, Diabetes mellitus, Systemic vasculitis.

References

• Gamuts in Radiology - Reeder and Felson - 4th ed (Springer, 2003).
• Khan AN, MacDonald S, Chandramohan M, Chandramohan H. Nephrocalcinosis. eMedicine. Updated: Jul 10, 2008.
• Shultz PK, Strife JL, Strife CF, McDaniel JD. Hyperechoic renal medullary pyramids in infants and children. Radiology. 1991 Oct;181(1):163-7.