Cystine crystalluria (crystals in the urine) and kidney stone formation are the only definitive symptoms of cystinuria. Kidney stones can cause their own symptoms including the presence of blood and/or signs of infection (frequent urination accompanied by a burning sensation and possible fever) in the urine due to the aggravation of tissues by the stone(s). Pain is the most common symptom, ranging from a constant dull ache to sharp stabbing pain and severe spasms.
Kidney stone pain, known as renal colic, is typically felt in the area between the ribs and the pelvis, wrapping from the small of the back through the side (flank) to the groin. The pain may migrate throughout this area, finally becoming more associated with the bladder and groin as a stone makes its way along the urinary tract. Men may experience pain in the testicles. The acute and chronic pains endured by people suffering with cystinuria can cause nausea and vomiting, or lead to tiredness and in some cases depression.
Novice stone formers may fail to recognize a kidney stone as the cause of pain which is often difficult to define and remote from the location of the kidney. However, experienced sufferers of cystinuria are likely to become familiar with their own stone pains and able to readily recognize stone events when they occur.
People with cystinuria have cystine crystals in their urine that can be identified by looking at the urine under a microscope. Additionally, patients with cystinuria typically produce stones that are 100% cystine, which can be analyzed at special laboratories. Finally, cystinuria can be diagnosed through genetic testing, which may be available at medical centers that specialize in kidney stone diseases.