As the levels of cystine in the urine increase, it forms cystine crystals, resulting in kidney stones. Cystine crystals form hexagonal-shaped crystals that can be viewed upon microscopic analysis of the urine. The other amino acids that are not reabsorbed do not create crystals in urine.The overall prevalence of cystinuria is approximately 1 in 7,000 neonates (from 1 in 2,500 neonates in Libyan Jews to 1 in 100,000 among Swedes). Pathophysiology
Cystinuria is characterized by the inadequate reabsorption of cystine in the proximal convoluted tubules after the filtering of the amino acids by the kidneys glomeruli, thus resulting in an excessive concentration of this amino acid in the urine. Cystine may precipitate out of the urine, if the urine is neutral or acidic, and form crystals or stones in the kidneys, ureters, or bladder. It is one of several inborn errors of metabolism included in the Garrods tetrad. The disease is attributed to deficiency in transport and metabolism of amino acids. Diagnosis
Blood: Routine hemogram along with blood sugar, urea, and creatinine. Urine: For cystine crystals, and casts. The most specific test is the cyanide–nitroprusside test
Ultrasound/CT scan to reveal if a stone is present. Genetic analysis to determine which mutation associated with the disease may be present. Currently genotyping is not available in the United States but might be available in Spain, Italy, UK, Germany and Russia (by private companies in Germany and Russia).Regular X-rays often fail to show the cystine stones, however they can be visualized in the diagnostic procedure  that is called intravenous pyelogram (IVP).
Heart abnormalities can occur as a result of NM, but the likelihood of that happening are not high. Mobility and orthopedics
Most children with mild NM eventually walk independently, although often at a later age than their peers. Some use wheelchairs or other devices, such as walkers or braces, to enhance their mobility. Individuals with severe NM generally have limited limb movement and use wheelchairs full-time. Due to weakness in the trunk muscles, people with NM are prone to scoliosis, which usually develops in childhood and worsens during puberty. Many individuals with NM undergo spinal fusion surgery to straighten and stabilize their backs.Although patients early on often have mobility in their joints that is past the normal range, as they age, joint deformities and scoliosis usually occur. If the person with nemaline myopathy keeps an eye on his or her joints early on, the problems with them can be detected when they begin and their progression can be delayed. Treatment of joint problems ranges from stretching exercises with physical therapy to surgical introduction of braces. The benefits of exercise in people with nemaline myopathy are still being studied, however, researchers have seen improvements in muscle function from low-intensity exercise. Vigorous exercise and the use of heavy weights should be avoided. Respiratory involvement
Attention to respiratory issues is critical to the health of many people with NM. Infants with severe NM frequently experience respiratory distress at or soon after birth, although this is only found in the rarest forms.