Azotemia, Familial

Hsu et al. (1978) described a family in which 6 persons in 3 generations had elevated serum urea with normal creatine levels, renal biopsy and all measures of renal function except urea clearance. Urea is both filtered at the glomerulus and actively secreted by the proximal tubule (Kawamura and Kokko, 1976). Furthermore, urea is reabsorbed actively by the tubule; this process is apparently brought into play particularly in states of low protein intake. Net reabsorption might be due to exaggerated active reabsorption or to deficient secretion. Whatever the precise nature of the defect, it appeared to be inherited as an autosomal dominant. Four instances of father-to-son transmission were demonstrated.