Skin content and plasma transport of vitamin A and beta-carotene in chronic renal failure.

The serum and cutaneous concentrations of beta-carotene and vitamin A and the serum concentrations of retinal-binding protein (RBP) and prealbumin were investigated in ten patients with chronic renal failure. The serum beta-carotene concentration was lower in the patients 1.3 +/- 0.7 mumol/l) than in the twenty-two healthy controls (2.4 +/- 0.9; P less than 0.01). The skin carotene concentration was also lower in patients than in controls (18.7 +/- 5.5 v. 24.6 +/- 9.9 nmol/g protein; P less than 0.05). By contrast, the patients' mean concentration of vitamin A in the skin was twice that of the healthy controls (11.0 +/- 4.8 v. 5.9 +/- 1.4 nmol/g protein; P less than 0.005) and in serum 3 times that of the controls (4.8 +/- 1.7 v. 1.8 +/- 0.3 mumol/l; P less than 0.001). The increase of serum vitamin A was accompanied by a rise in the RBP concentration, but the concentrations of vitamin A-esters and prealbumin remained in the normal range. It is suggested that vitamin A may accumulate in the skin as a result of an increased transfer of the vitamin by RBP. A possible relationship between high skin levels of vitamin A and uraemic skin symptoms is discussed.