Implications of Hypervitaminosis A on the Calcium-Phosphate Metabolism and on Blood Lipids in Hemodialysis

Abstract

Serum levels of vitamin A (VA) were measured in 71 hemodialysis (HD) patients and in 30 normal controls. 65 of the 71 patients were taking multivitamin preparations (MP) containing VA. The HD patients had significantly greater values: 7.81 ± 2.86 μmol/l (224 ± 82 μg/dl) versus 3.97 ± 0.97 μmol/l (114 ± 28 μg/dl; p < 0.0005); those taking MP with large doses of VA showed the highest levels. Patients were divided as having normal (group I, n = 21) or elevated (group II, n ≈ 50) serum levels of VA. Patients of group II had higher levels of serum calcium (Ca) and lower of serum phosphate (P) and PTH than those of group I. Four months after the withdrawal of oral VA, the serum levels of VA and Ca fell significantly in group II, while the serum P increased. On the contrary, in group I serum levels of VA, Ca and P remained unchanged. Serum triglycerides (TG) were significantly higher in group II but did not change after the withdrawal of VA. No differences between both groups of patients were observed for age, time on HD, residual diuresis, residual renal function, serum levels of cholesterol (CL) or anemia. A retrospective study of 18 hepatic biopsies of HD patients disclosed hypeφlasia of Ito cells (VA-storaging cells) in 7 of them. These 7 biopsies belonged to patients who had taken large amounts of oral VA. Our data indicate that prolonged VA intake in HD patients is followed by an increase of serum CA, a decrease of serum P and PTH and a hepatic accumulation of VA. Since we observed a correlation between oral intake of VA and serum levels of VA, it is necessary to know the VA content of MP administered to HD patients.

Appropriate Vitamin Therapy for Dialysis Patients

“…Hemodialysis patients not receiving vitamin A suFplements have serum vitamin A levels that are two to five times higher than levels in patients with normal renal function (56). Providing a daily supplement of between 2,500 and 25,OOO IU of vitamin A in hemodialysis patients results in serum levels four to ten times higher than levels found in normals (57)(58)(59). In addition, hypervitaminosis and toxicity of vitamin A has been reported in dialysis patients given TPN solutions containing high amounts of vitamin A (60).…”