By, Dr. Nishan Wijesinha (Specialist/Consultant), MIS Services, 107 St. Anthony-â„¢s road, Colombo 3.

Cystine kidney stones are due to the results of an excess of Cystine in the urine. Cystine which is considered a non-essential amino acid is the least soluble of all naturally occurring amino acids. As a result Cystine tends to precipitate out of urine and form stones (calculi) in the urinary tract.

Small stones are passed in the urine. However, big stones remain in the kidney (nephrolithiasis) impairing the outflow of urine while medium-size stones make their way from the kidney into the ureter and lodge there further blocking the flow of urine (urinary obstruction).

Obstruction of the urinary tract puts pressure back up on the ureter and kidneys causing the ureter to widen (dilate) and the kidneys to be compressed. Obstruction also causes the urine to be stagnant (not moving), which leads to repeated urinary tract infections. The pressure on the kidneys and the urinary infections results in damage to the kidneys. The damage can progress to renal insufficiency and end-stage kidney disease, requiring renal dialysis or a transplant.

The Cystine stones are responsible for all the signs and symptoms including:

• Hematuria — blood in the urine.
• Flank pain — pain in the side, due to kidney pain.
• Renal colic – intense, cramping pain due to stones in the urinary tract.
• Obstructive uropathy — urinary tract disease due to obstruction.
• Urinary tract infections.

These crystals can adversely affect many body systems. The kidneys and eyes tend to suffer the most damage, with retinopathy and short statue and swelling under and around the eyes including black patches resulting from its effects.

Cystine is found in very large percentage in whey proteins from non-pasteurized milk; infant milk formulas, cereals, and in many other milk foods and vitamin supplements; which the Ministry of Health should bring in a quick banning to stop such products from entering the local consumer market.