38 C.F.R. § 4.115
Albuminuria alone is not nephritis, nor will the presence of transient albumin and casts following acute febrile illness be taken as nephritis. The glomerular type of nephritis is usually preceded by or associated with severe infectious disease; the onset is sudden, and the course marked by red blood cells, salt retention, and edema; it may clear up entirely or progress to a chronic condition. The nephrosclerotic type, originating in hypertension or arteriosclerosis, develops slowly, with minimum laboratory findings, and is associated with natural progress. Separate ratings are not to be assigned for disability from disease of the heart and any form of nephritis, on account of the close interrelationships of cardiovascular disabilities. If, however, absence of a kidney is the sole renal disability, even if removal was required because of nephritis, the absent kidney and any hypertension or heart disease will be separately rated. Also, in the event that chronic renal disease has progressed to the point where regular dialysis is required, any coexisting hypertension or heart disease will be separately rated.
38 C.F.R. §4.115