Renal calculi (stones)

General Information

Renal stones often develop in response to elevated levels of urinary solutes such as calcium, uric acid, oxalate and sodium, as well as decreased levels of stone inhibitors such as citrate and magnesium. Low urinary volume and abnormally low or high urinary pH also contribute to the formation of renal stones. The different types of renal stones are listed below. Most stones are a mixture of different crystal types.

• Calcium oxalate (most common):
  • Calcium oxalate monohydrate (whewellite)
  • Calcium oxalate dihydrate (weddellite)
• Calcium phosphate:
  • Calcium mono-hydrogen phosphate dihydrate (brushite)
  • Carbonate apatite
• Struvite (magnesium ammonium phosphate)
• Urate
• Cysteine

Renal calculi and stones from other sources (e.g. gallstones, salivary stones) are analysed by quantitative fourier transform infra red (FTIR) spectroscopy. Results are reported as weight of stone, with a description and/or % composition, as well as site location.