Zinc tolerance tests in chronic uremia

Area of Science:

• Nephrology
• Nutritional Science
• Gastroenterology

Background:

• Chronic uremia affects mineral metabolism.
• Vitamin D plays a role in nutrient absorption.
• Zinc deficiency is common in patients with kidney disease.

Purpose of the Study:

• To investigate the effect of vitamin D on intestinal zinc absorption in patients undergoing maintenance hemodialysis.
• To compare zinc absorption between hemodialysis patients with and without vitamin D therapy and healthy controls.

Main Methods:

• A zinc tolerance test was performed on 12 control subjects and 20 hemodialysis patients (10 on vitamin D, 10 not).
• Subjects ingested 50 mg of zinc after baseline plasma zinc measurements.
• Plasma zinc levels were measured hourly for 4 hours post-ingestion.

Main Results:

• Hemodialysis patients not receiving vitamin D showed significantly lower peak plasma zinc levels compared to controls and patients on vitamin D.
• No significant difference in zinc absorption was observed between controls and patients on vitamin D therapy.
• Two patients demonstrated normalized zinc tolerance tests when on vitamin D therapy, with abnormal tests when off it.

Conclusions:

• Intestinal zinc absorption may be impaired in chronic uremia.
• Abnormal vitamin D metabolism in uremia likely contributes to impaired zinc absorption.
• Vitamin D supplementation may be beneficial for improving zinc status in hemodialysis patients.