Cystinuria in children and young adults: success of monitoring free-cystine urine levels

Abstract

Medical treatment of cystinuria is often disappointing. Patients undergo frequent surgery, which is often followed by early relapse. The aim of our study was to evaluate the efficacy of medical treatment of cystinuria, to prevent formation or to reduce the numbers and dimensions of renal stones. Twenty cystinuric patients were treated with a combined approach, including cystine-binding drugs. Free and bound urine cystine levels were measured every 4 months. Drug dosage was adjusted to maintain free urine cystine level below 100 micromol/mmol creatinine. Eighteen patients completed the study; detection of new stones was reduced from 0.28 per year to 0.03 per year, and, in six patients, the numbers and dimensions of pre-existing renal stones were reduced. Surgery was required in one subject, and no relapse was observed 12 months afterwards. The dosage required to achieve target levels was closely correlated with patient body weight: older children required a lower dose. Medical management of cystinuria is feasible. The treatment must be personalised in children, as the amount of drug required is strictly dependent on body size.

Hereditary causes of kidney stones and chronic kidney disease

“…Most patients with cystinuria present in childhood with stone formation. Average age of detection of a first renal stone is about 12-13 years [28], with 50% forming a first stone in the first decade of life and another 25% in teenage years. Males and females have a similar age of onset but more male patients than female patients present in the first 3 years of life and males tend to have new stones more frequently than females.…”

Therapy modifies cystine kidney stones at the macroscopic scale. Do such alterations exist at the mesoscopic and nanometre scale?

“…Most reports on cystinuria have been devoted to the genetic aspect or medical management (Pras, 2004;Dello Strologo et al, 2002) but no study has investigated the structural parameters of cystine stones. Such structural characterization on pathological calcifications can be performed either through various classical physical techniques (Evan et al, 2007;Rao et al, 2011;Bazin et al, 2006), such as scanning electron microscopy (SEM) (Grà cia-Garcia et al, 2011;Dessombz, Mé ria et al, 2011, micro-computerized tomography (Williams et al, 2012;Kaiser et al, 2011), Fourier transform infrared (FTIR) and Raman spectroscopy (Quy Dao & Daudon, 1997;Estepa & Daudon, 1998;Guerra-Lopez et al, 2008;Wilson et al, 2010), proton induced X-ray emission (Pineda-Vargas et al, 2009), and laser ablation methods (Stepankova et al, 2013), or through techniques specific to large instruments, such as micro X-ray fluorescence (Bazin et al, 2007), micro X-ray absorption spectroscopy Carpentier et al, 2010;Nguyen et al, 2011), micro FTIR spectroscopy or neutron scattering (Bazin, André et al, 2012).…”

Genetic Causes of Kidney Stones and Kidney Failure

“…The average age at diagnosis is about 12 years, and males have more stones than females [33]. Since a neonatal screening program demonstrated an incidence of persistent cystinuria of 562 cases per million infants, seven times higher than the estimated rate of cystinuria in adults, it appears that many cystinurics will not form kidney stones [34].…”