Nephrotic syndrome in spontaneous thymoma rats, Buffalo/Mna

Biochemical and histological studies for nephrotic syndrome were performed in Buffalo/Mna (B/Mna) rats which spontaneously develop thymoma. These rats showed a steroid-resistant nephrotic syndrome characterized by proteinuria, hypoalbuminernia, hyperlipidemia, and slight edema from their early ages, and light microscopical features of focal and segmental glomerular sclerosis in their advanced ages. The proteinuria was ascribed to a remarkable increase in albumin excretion (albuminuria). A continuous rise in urinary protein was observed from 10 to 20 weeks of age and the peak was maintained thereafter. This period almost coincides with the early stage of thymic abnormality as weight change before it is recognized as thymoma.