Pulmonary dysfunction in adults with nephropathic cystinosis

Objective: To characterize the pulmonary dysfunction in patients with nephr opathic cystinosis after renal transplantation. Design: Cross-sectional analysis of consecutive adult patients. Patients: Twelve adult, nephropathic cystinosis patients and 3 adult, ocula r, nonnephropathic cystinosis patients admitted to the National Institutes of Health Clinical Center. Results: The 12 nephropathic cystinosis patients (age range, 21 to 40 years ) show ed an extraparenchymal pattern of restrictive lung disease, with ins piratory and expiratory dysfunction. Specifically the mean FVC was 58% of p redicted, the mean FEV1 was 57% of predicted, and the mean total lung capac ity was 66% of predicted, while the mean residual volume mas normal. Furthe rmore, the mean maximal inspiratory pressure for the eight patients tested was 40% of predicted, and the mean maximal expiratory pressure was 26% of p redicted, Two patients died of respiratory insufficiency. All the patients had lived at least 17 years while lacking compliant cystine-depleting thera py with oral cysteamine. Seven patients had a conical chest, restricting ex cursion, and 10 of the 12 patients had evidence of the myopathy that typifi es late cystinosis. In fact, the severity of pulmonary disease correlated d irectly with the severity of myopathy in our group of 12 patients. In contr ast, the lung parenchyma was essentially normal as gauged by chest radiogra phs and CT scans of the lung. The three patients with nonnephropathic cysti nosis displaced entirely normal pulmonary function. Conclusion: The distal myopathy characteristic of nephropathic cystinosis r esults in an extraparenchymal pattern of restrictive lung disease in adults who have not received long-term cystine depletion. Whether or not oral cys teamine therapy can prevent this complication remains to he determined.